Laguna S 2.1

Customer's 2018 Silverado kills a brand-new battery in about four days sitting. Alternator tests fine. How do I actually run a parasitic draw test on this thing and what number am I looking for?

Slow-crank complaint, battery load-tests good, starter draws about normal amperage. I want to do voltage-drop tests on the starter circuit. Where do I put the leads and what drops are acceptable?

Doing a brake job on a Camry, pads are down to nothing and the rotors are grooved. How do I decide whether I can turn the rotors or have to replace them?

Guy brings in a trailer with tires that have deep tread but look a little cracked. How do I tell how old the tires are and when do I tell him they're done?

Doing a brake flush on a 2015 F-150 that calls for DOT 3. I've only got DOT 4 and a bottle of DOT 5 on the shelf. Can I use either one?

Got a Honda with a steady misfire on #3, coils and plugs swapped, injector swapped, still on #3. When do I go to a compression test versus a leak-down, and what results tell me it's mechanical?

Chrysler minivan with a U0100 lost communication with ECM and half the modules on the network dropping out intermittently. How do I check the high-speed CAN bus with a meter before I start pulling connectors?

New tech mounting wheels back on cars. What's the right way to torque lug nuts and do I really need to have the customer come back to re-torque?

Replacing a condenser on a 2012 Accord with R-134a. After I get it back together, how long do I pull vacuum, and how do I know how much refrigerant to put in?

We've been an R-134a shop forever and now the 2020+ stuff coming in is R-1234yf. What's actually different about servicing it besides the fittings?

Customer wants me to put 5W-30 conventional in his 2021 Toyota because 'that's what he's always run.' The cap says 0W-16. Does it matter?

Fleet customer with 2019 Ram 6.7 Cummins has a DEF quality warning and derate countdown. He swears he just filled it. What do I check and what are the rules on the DEF itself?

Peterbilt with a Paccar MX-13 keeps coming back with DPF high soot load codes and the driver says the forced regens only help for a week. What's the actual diagnostic path before I sell him a DPF cleaning?

2006 Duramax LBZ hard-starts after sitting overnight but fires right up if it's been shut off for less than an hour. Runs fine once it's going. Where do I start?

I'm about to replace the inverter coolant pump on a 2017 Prius and the high-voltage cables run right over it. What's the exact safety sequence before I touch anything orange?

Doing the timing belt on a 2008 Honda Odyssey J35. What else goes with it, and how do I make sure I haven't screwed up the timing before I put the covers back on?

Subaru 2.5 with coolant loss, no visible leak, white smoke sometimes and the overflow bottle bubbles. How do I confirm a head gasket without tearing it down?

Customer's Escape has a growl that gets louder with speed, and it changes when she swerves left or right. She's been told 'tires' twice. How do I nail down a wheel bearing versus tires?

2014 Malibu with a P0304 and a flashing check engine light. Boss said 'swap it and see.' Swap what, in what order, and why is the light flashing?

6.0 Powerstroke... actually no, a 2011 Cummins ISX15 with low power, no codes, and rail pressure that sags under load. How do I test the injectors for return flow and what's the shop-air side of that?

I just started at a small shop and the owner wants me to start doing A/C recharges. Do I need some kind of license to buy refrigerant and work on car A/C?

DOT roadside guy wrote up one of our customer's dump trucks for tires. What are the actual tread depth minimums for a commercial truck, front versus rear?

Customer with a 2015 Ram 2500 diesel wants us to do a 'delete' — DPF, EGR, and a tune. We're in Jacksonville and Florida doesn't do emissions testing, so is it legal?

Opening a two-bay shop in Clay County. What are the rules on my used oil, old filters, and antifreeze — can I just have the guy with the truck take it?

In Florida, does a customer really have to sign a written estimate before I touch the car? Where's the line, and what if the job grows once I'm in there?

Evaporator's shot on a 2009 Civic and the customer's just going to scrap the car. Can I just crack the line and let the R-134a out since the car's going to the crusher anyway?

Doing an annual on a tandem dump with Type 30 brake chambers. What's the pushrod stroke limit I'm checking against, and how do I actually measure it?

2016 Altima with 110k miles, P0420, and the OE cat is $1,800. Customer wants the $250 universal converter off the internet. We're in Florida. What are the rules on installing an aftermarket converter?

Apprentice is diagnosing a charging problem on a 2012 Tahoe. Battery's charged, truck's running at idle, and he says 'I'm going to pull the negative cable off — if it keeps running the alternator's good.' What's wrong with that?

Tire guy in the next bay mounts four wheels on a Tacoma, hits every lug with a 1/2-inch impact until it stops, drops the truck, and sends it. Customer's back in two weeks with a steering wheel shimmy under braking. What happened?

Customer limps in with the temp gauge pegged. The lube tech pops the hood, grabs a rag, and starts twisting off the radiator cap to 'see if it's got coolant.' What's about to happen?

Head gasket job on a 2007 Chevy 5.3 LS. Tech cleans up the old head bolts on the wire wheel, oils the threads, and torques them to 22 ft-lb then 90 degrees like the book says. Where's this going wrong?

Fuel filter service on a 2012 Duramax LML. Tech spins on the new filter, hits the key, cranks it 20 seconds, cranks again, third time it fires and runs. He says it's good. Why might this truck be back on a hook in a month?

There's a diesel mist and a smell on a running 2015 Ram 6.7 Cummins. Tech is running his bare hand along the high-pressure lines from the rail to the injectors to feel for where it's spraying. Stop him?

Camry Hybrid comes in with no A/C, compressor's dead. Tech pulls the electric compressor, installs a new one, and tops the system with the same PAG 46 he uses on everything before charging. Anything wrong?

Tech is doing an A/C 'recharge' on a 2010 Impala: he screws a 12-oz can with sealer onto the low side, runs the engine, watches the low-side gauge until it reads 35 psi, and calls it done. What's he done wrong?

Restoration guy brings in a 1999 Suburban with ABS and says he 'upgraded' it with DOT 5 silicone fluid for long-term storage. Now the pedal is spongy and the ABS is chattering at low speed. What's going on?

Fleet has a 2008 International with a DT466 and a wet-sleeve design. Shop refills the cooling system after a water pump with 50/50 green conventional automotive antifreeze off the shelf, no additives. Two years later they're pulling the engine for coolant in the oil. Connect the dots.

Tech gets a Corolla with P0420, reads the code, sells the customer a new converter, installs it, clears the code, and the light comes back in 400 miles. He wants to warranty the converter. What did he miss?

Tech is replacing a clockspring on a 2013 Accord. He disconnects the battery negative, immediately unbolts the airbag, sets it face-down on the bench, and starts probing the yellow connector with a test light to check continuity. Rank the mistakes.

I'm setting floor joists and some of them have a visible bow along the edge. Which way do I put them in, and does it actually matter?

Gable roof, 6/12 pitch, building is 24 feet wide outside to outside, ridge is a 2x (1-1/2 in. thick). How long is my common rafter from the birdsmouth heel to the plumb cut at the ridge, and how do I get there with a framing square?

Laying out a wall plate for studs at 16 on center. Where do I put my first mark so the 4x8 sheathing breaks on a stud?

Homeowner wants a 6-foot slider in an exterior bearing wall of a one-story ranch with trusses. What do I need to know to size the header without calling an engineer, and how do I support it?

What's the right way to nail off a face-mount joist hanger like a Simpson LUS210? I've got a guy who fills the ones he feels like and skips the rest.

How do I toe-nail a stud to a plate so it actually holds and doesn't split or kick out of position?

I'm laying out batter boards and strings for a 24 by 40 addition foundation. How do I make sure it's square before we dig?

The plumber needs to run a 2-inch drain through a row of 2x10 floor joists. What are the rules on where and how big I can let him drill?

Laying 3/4 T&G subfloor over 2x10s at 16 on center. Walk me through doing it so it doesn't squeak or hump later.

What's the standard nail schedule for 7/16 OSB wall sheathing, and when do I need to block the horizontal panel edges?

Total rise from finished floor to finished floor is 108 inches, straight run, 2x12 stringers, 1-inch treads. Lay out the stringer for me: how many risers, what rise, what run, and what do I have to watch at the bottom and the throat?

How deep can I cut the birdsmouth on a 2x8 rafter sitting on a 2x4 wall, and how do I lay out the seat and heel?

I'm building up a three-ply 2x12 girder from 16-foot stock for a 32-foot floor beam over posts. How do I nail it and where do the joints go?

What order do I flash a flanged window in a house-wrapped wall so water can't get behind it?

First time framing a floor with TJI I-joists instead of sawn lumber. What do I have to do differently?

Cutting hip rafters for a 6/12 hip roof with the commons already up. How do I get the hip length and cuts, and what's this about dropping the hip?

Inspector told me my collar ties don't count as rafter ties. I thought they were the same thing. What's the difference and where does each one go?

The grade stamp on the 2x10s says SPF, No.2, S-DRY, with a mill number and an agency logo. What does each of those tell me and why would the inspector care?

Building a ground-level deck with 4x4 posts in the dirt and joists a few inches off grade. What treated lumber and hardware do I spec so it doesn't rot or corrode?

Plans call for a 3-foot cantilever off the second floor for a bump-out that carries the exterior wall and roof above. Floor joists are 2x10 at 16. What are the rules for that cantilever?

Plumber wants to bore a 3-inch hole through the 2x6 studs of an exterior bearing wall for a shower drain. What does the code let him do?

The HVAC guy cut a 3-inch-wide notch across the double top plate of a 2x4 bearing wall for a duct. The framing inspector flagged it. What's the fix he's expecting?

Setting a treated sill plate on a new stem wall. What size anchor bolts, how far apart, and how deep do they have to be?

New 30 by 50 house with a vented attic, soffit vents and a ridge vent. How much net free vent area does the code want, and can I use the smaller 1/300 number?

I frame in Ohio and just took a job in Jacksonville. My roofer says I can't do rafter tie-downs the way I'm used to, using the IRC Table R802.11 uplift numbers. What's different in Florida?

Building a house in a wind-borne debris region on the Florida coast. The owner doesn't want to pay for impact windows and asks if plywood shutters are legal. What does the code say?

Basement stairs in a new house: what are the code limits on riser height, tread depth, headroom, and how consistent the steps have to be?

Framing inspector wants me to re-do some of my double top plates. What are the rules on where the splices go and the corners?

Crew is hanging a 12 by 16 deck off a two-story brick house. They set the 2x10 ledger tight against the brick, ran 3/8 by 4-inch lags every 24 inches through the brick into whatever's behind, no flashing, and are ready to hang joists. What's wrong?

Remodel on a 1960s ranch, 2x6 rafters at 24 with a 2x8 ridge board, 24-foot span, 6/12. Owner wants a vaulted living room, so the crew pulled the ceiling joists out of that 16-foot section and is drywalling the rafters. Walls look fine so far. What's coming?

HVAC contractor needs to get an air handler into the attic of a truss-framed house. His guys cut out the bottom chord and one web of two adjacent trusses to widen the hatch to 30 by 48, and the framer says he'll sister 2x6s alongside the cut chords and call it good. Inspection is tomorrow. What do you tell them?

Walking a deck rough-in: 2x10 joists in LUS28 hangers, the hangers are nailed with 1-1/2 inch galvanized roofing nails in the face holes and the diagonal joist holes are empty, and the joists are sitting about 3/4 inch above the hanger seat because the hanger was nailed up first. Owner says it feels solid. Is it?

The plumber ran a 3-inch drain along the bottom of a 2x10 floor joist and cut a 3-inch-deep notch across the bottom edge right in the middle of a 14-foot span, then screwed a steel strap across the notch. He says the strap makes it stronger than before. Does it?

New crew sheathed a 40-foot wall with 7/16 OSB. They started layout from the corner with the first stud at 16 (not 15-1/4), butted every panel tight with no gap, and the gun was set so the nail heads are buried about 1/8 inch into the face. It looks clean. What are you going to make them fix?

Framer put a double 2x10 header over a 6-foot patio door in a bearing wall, but instead of jack studs he end-nailed the header through the king studs with four 16d each side and ran cripples up to the top plate. He says the nails and the cripples carry it. Does that pass?

Truss roof on a new house in Clay County, Florida, 130 mph wind zone. The framer nailed the 7/16 OSB roof deck with 8d smooth-shank gun nails at 6 on the edges and 12 in the field, used H2.5 clips on every other truss with three nails each because that's how he did it up north, and wants to call for the dry-in inspection. What's going to happen?

The concrete crew wet-set J-bolts in the stem wall at 8 feet on center and the closest bolt to each corner is about 30 inches from the end of where the sill plate will stop. Framer says he'll just add a few Tapcons where he needs them. Good enough?

Finishing a deck that sits 4 feet above grade. The rail is 34 inches tall, 2x2 pickets are spaced 5 inches clear, and there's an 8-inch gap between the deck boards and the bottom rail. What's the inspector going to flag?

Deck guard posts: the crew notched 4x4 posts halfway through to sit flush on the outside of the rim, ran two 1/2-inch carriage bolts through the notched part into the 2x10 rim, no blocking behind the rim, and then hung the guard rails. Bolts are tight and the posts feel okay. Why is the inspector or anyone with experience going to make them redo it?

Apprentice cut all 26 common rafters for an 8/12 gable off a pattern he laid out with the line length measured to the center of the ridge, using a 2x ridge. He also set the birdsmouth so the seat cut runs out 1/2 inch past the outside face of the 2x4 plate. First pair went up and the ridge won't sit right. What did he do and what does it mean for the rest of the stack?

I'm hanging 1/2" board in a bedroom with wood studs 16" on center, no adhesive. How far apart do my screws need to be on the walls versus the ceiling?

Painter wants a satin finish on a big living room wall that gets raking light from a bank of windows. What level of drywall finish should I be giving him and what does that actually mean in terms of coats?

Ceiling joists in this addition are 24" on center and the builder wants to blow in R-38 cellulose after we hang. Can I just use regular 1/2" board on the ceiling like I do everywhere else?

Why do most hangers run wall sheets horizontally instead of standing them up, and what do I do about the butt joints when I go horizontal?

What's the actual difference between setting-type compound, all-purpose premix, and topping compound, and when do you reach for each?

Paper tape versus self-adhesive fiberglass mesh tape — I keep hearing arguments both ways. What's the real rule?

How deep am I supposed to set a drywall screw, and what happens if I go too deep?

What are my options for outside corner bead and how does each one get attached?

I've got a 70-foot-long hallway ceiling with no breaks in it. Do I need control joints in the drywall and if so where?

What does 'floating' the inside corners mean when hanging, and why do it?

Fire-rated assembly on the plans calls for 5/8" Type C on the ceiling but the yard only has Type X. Same thickness, same rating on the label — can I sub it?

How do I actually put on a Level 5 skim coat on a whole room without it taking three days?

What's the difference between moisture-resistant 'greenboard', mold-resistant board, and glass-mat board, and where does each belong in a house?

It's cold and the house isn't heated yet. What temperature does the room need to be for taping and finishing, and for how long?

Doorknob went through the wall and left a 4" hole in 1/2" drywall. What's the clean, permanent way to patch that without a mesh patch showing?

Customer wants a home office wall that actually blocks noise from the kids' playroom. Wall is already framed as a standard 2x4 single-stud wall. What gives the biggest STC jump for the money, and what kills it?

How do I sand joints without wrecking the paper and leaving scratches that show through the paint?

I need to match an existing knockdown texture on a patched ceiling. What's the process and where do people screw it up?

First time hanging on 20-gauge steel studs at 16" o.c. What's different from wood — screws, which way I work, anything about the studs themselves?

Attached two-car garage with a bedroom above it. What drywall does code want on the garage ceiling and on the walls between the garage and the house?

We framed a dropped soffit over the kitchen cabinets that's open to the stud wall behind it, and the inspector says we can't hang until something is fixed. What's he looking for?

Tub-shower combo with a tiled surround. Can I hang greenboard behind the tile, and does code say what has to go there?

Homeowner wants a little storage closet under the basement stairs with a door on it. Does the drywall in there matter to the inspector?

Hanging 5/8" board on wood framing — how long does the screw have to be per code, and does the rule change on steel?

Townhouse job: the wall between units is a 1-hour rated assembly. What do I have to do differently on that wall than on a regular interior wall so it passes?

I'm in Clay County, Florida and want to start a drywall-only company. Do I need a state contractor license from DBPR to bid drywall jobs?

Bathroom has an exhaust fan but the walls stay damp. Can I put water-resistant greenboard over a poly vapor barrier on the exterior wall behind the tub?

Crew is hanging a 1,600 sq ft great-room ceiling with regular 1/2" board, running the sheets parallel to the 24" o.c. trusses because it 'saves a cut.' Blown-in insulation goes in tomorrow, then we spray knockdown. Anything wrong?

It's January, the house has no HVAC yet, temps are hovering around 40°F and the finisher is running a propane torpedo heater in a closed-up house. He's taping with all-purpose and planning to recoat every morning and have it painted in four days. What's going to happen?

New guy taped the whole house with fiberglass mesh tape, including all the inside corners, and bedded everything in lightweight all-purpose. Looks fine today. What am I going to see in 90 days?

Apprentice hung a bedroom and I'm walking it. Screws are every 8" on the walls, a few are angled and I can see torn paper around maybe one in ten heads, and there are a couple of runs where the screw obviously missed the stud and he just left it. Callbacks coming?

Two-story house with roof trusses. Every winter the homeowner gets a 1/4" gap between the ceiling and the top of the interior partition walls, and it closes back up in summer. The finisher has 'fixed' it twice with mud and it keeps coming back. What's actually happening and what's the real fix?

Remodel bath: sub put 6-mil poly on the exterior wall, greenboard over that in the tub surround, and is about to thinset tile directly to the greenboard. Anything you'd stop?

Long hallway with a row of west-facing windows, walls finished to Level 4, painted with an eggshell. Homeowner is furious because at 5 pm every joint and screw shows as a stripe. Finisher says it's a paint problem. Who's right?

Walking a hang job: sheets on the long wall have all the butt joints lined up on the same stud top and bottom, the top course was cut so the joint lands right at the corner of the door opening, and every sheet is jammed tight to the slab. Finisher hasn't started. What do I make them fix?

Sound-rated ceiling: crew installed resilient channel across the joists at 24" o.c., then hung double 5/8" with 2-1/2" screws so they'd 'get good bite,' and the recessed can lights were cut in afterward. Drywall is tight to the walls. Will it perform?

GC says we can start hanging Monday to make the schedule; the electrical rough, plumbing rough, and insulation inspections are all scheduled for Wednesday. Insulation is in. Anything wrong with that plan?

Flip in Cape Coral, house built 2007. Copper on the AC coil is black, the second evaporator coil has already failed, there's a faint sulfur/rotten-egg smell, and all the electrical wire ends in the boxes are dark. The seller's fix is 'paint with Kilz and put in a new coil.' What is this and what's the real remediation?

I've got a 200A panel and want to add a 50A circuit for a hot tub about 60 feet away. What wire, what breaker, and what else do I need at the tub?

Quick check: what size copper NM-B do I need for a standard 20A receptacle circuit, and for a 15A lighting circuit?

I'm putting two 12-2 NM cables and one 12-3 NM cable into a box with a single duplex receptacle and internal clamps. How do I figure out what size box I need?

Upgrading a house from 100A to 200A service, meter to main panel run is about 10 feet. What size aluminum service entrance conductors can I use, and what copper if I go that route?

I need to run a 20A 120V circuit 250 feet out to a well house that draws about 16 amps. What wire size so the pump doesn't burn up, and how do you actually run the math?

I'm wiring a 10 HP 230V single-phase motor for a shop compressor. The nameplate says 42 FLA. How do I size the branch circuit conductors and the breaker, and why don't the two match?

Customer's 480V feeder to a rooftop unit keeps tripping the breaker after heavy rain. I want to megger it before I pull new wire. How do I do the test right, and what readings mean it's bad?

Wiring a hallway light with a switch at each end using 14-2 from the panel and 14-3 between the switches. Which wires go where on the 3-ways?

I've been tightening panel lugs by feel for 20 years. An inspector just told me that's not good enough anymore. What's he talking about?

1970s house with aluminum branch-circuit wiring, owner can't afford a rewire but wants it safer. What's the right way to fix the receptacle connections?

Installing a 100A subpanel in the same house 20 feet from the main panel. Do I bond the neutral bar in the subpanel like the main, or not?

New service on a house. I drove one 8-foot ground rod. Do I need a second one?

Homeowner is swapping a gas range for a 12 kW electric range and there's no circuit. What do I run and what receptacle goes in?

I want to run one 12-3 to the kitchen and split it into two 20A countertop circuits sharing the neutral. Anything special at the panel?

How many #12 THHN can I legally pull in 3/4-inch EMT, and how do you figure that if it's a mix of sizes?

I'm pulling four 20A 120V circuits through one 3/4 EMT from a panel to a shop, each circuit with its own neutral, plus one ground, THHN. Do I need to upsize the wire?

Small church wants a 20-amp circuit for a bank of LED sign lights that stays on all night, load is right at 18 amps measured. Is a 20A breaker and #12 fine?

Customer bought a Level 2 EV charger that can be set to 48 amps and wants it hardwired in the garage, 30 feet from the panel. What breaker and wire?

Explain to me like I'm new: what's the actual difference between a GFCI and an AFCI, and why do I need both in a bedroom with a bathroom off it?

I need a 90 on 1/2-inch EMT that lands the stub 12 inches off the floor. Where do I mark it and how do I bend it on a hand bender?

Rough-in on a new house. Which receptacles actually have to be GFCI protected?

How far apart do wall receptacles have to be in a living room, and does a 3-foot wall between two doors need one?

My kitchen plan has a 10-foot island with no cabinets, a peninsula, and 14 linear feet of counter along the wall with the sink in the middle. How many receptacles and circuits under the current code, and what changed recently for the island?

Inspector failed my panel because the water heater is too close in front of it. What are the actual clearance numbers?

I'm in Clay County, Florida. Can a homeowner pull their own permit and replace their own service panel, and can my unlicensed helper do electrical side jobs on his own?

Doing a 200A service change on a house where the main panel is in the garage, meter is on the outside wall. Inspector says I need something outside now. What?

Trenching a 20A GFCI circuit to a shed in Jacksonville, Florida. How deep does it have to be, and do I have to call anyone before I dig?

Pulling a permit for a whole-house rewire in Florida in 2026. Which edition of the NEC does the inspector enforce, and are there receptacle types I have to use?

Handyman wired a customer's hot tub: 6-3 NM-B from a 50A GFCI breaker, ran it out through the wall into 3/4 PVC conduit down into the ground and over to the spa pack, with a non-fused disconnect right next to the tub. He says it's all in conduit so it's protected. What's wrong?

I'm looking at a detached garage a previous electrician fed from the house with 2-2-4 aluminum SER (two hots and a neutral), 60A breaker, 40 feet underground in PVC. The garage panel has the bonding screw installed and no ground rod. Owner wants me to add a couple circuits and sign off. What do I tell him?

Homeowner added a garage circuit himself. Panel is full, so he stuck the new #12 under the same breaker screw as the existing #12 on a 20A Square D Homeline breaker, tightened it down good, and it's been working for a year. Fine to leave?

During the last hurricane my neighbor ran his 7500W portable generator into the house by plugging a cord with two male ends into his dryer receptacle and flipping the main breaker off. He says it works great and wants me to make him a heavier cord. What's the problem?

Finishing a bonus room over a garage. The GC bought a case of cheap 6-inch recessed cans marked 'non-IC' because they were on sale, and the insulator is coming tomorrow to blow R-38 cellulose over the whole ceiling. Anything I should say before then?

Remodel plans show the existing 200A panel staying where it is but the room around it becoming a master bathroom, with a linen closet built against the adjacent wall. Panel stays accessible, cover clears. Architect says no electrical changes needed. What did they miss?

Customer says his kitchen breaker kept tripping when he ran the microwave and toaster together, so his brother-in-law swapped the 15A breaker for a 20A and it hasn't tripped since. The cable on that circuit is 14-2. He's happy. Should he be?

I'm doing a final walkthrough on a new house in a lightning-heavy area. Service is done with two rods, the copper water line is bonded at the panel, and the plumber ran yellow CSST gas line from the meter to the range, water heater, and furnace, with the black iron nipple at the meter bonded with a #6 to the ground bar. Plumber and electrician both say they're done. Are they?

Service call: a #12 neutral in a 10-year-old panel is scorched and the wire nut in the kitchen ceiling box is melted, but neither breaker on that 12-3 ever tripped. The two hots are on a pair of single-pole 20s stacked in slots 3 and 5 on the same side of the panel. Both circuits measure normal voltage. What happened?

Apprentice roughed in an EV charger circuit: 6-2 NM-B from a 60A breaker, 45 feet through the attic, into a hardwired EVSE set to 48A. Wire and breaker are both 'rated 60' per the label on the cable reel. Inspector wants it redone. Why?

Flipper installed a new 4-wire NEMA 14-30 dryer receptacle to 'update' the laundry, but the existing cable in the wall is 10-2 NM with ground from the 1990s. He wired the receptacle with a jumper from the neutral terminal to the ground terminal so the new 4-prong cord would have a neutral. Dryer runs fine. What's wrong with this?

HVAC crew set a new 4-ton condenser. Nameplate says RLA 18.6A compressor, fan FLA 1.5A, Minimum Circuit Ampacity 25, Max Fuse/Breaker 40. The electrician on site says the old 30A breaker and #10 NM to the disconnect are 'more than enough since it only draws 20 amps' and he's leaving it. The old non-fused pull-out disconnect stays too. Is he right?

I'm checking charge on a straight-cool split with a fixed-orifice (piston) metering device. What do I measure and what am I looking for?

Same question but the system has a TXV. What's my charging target and where do I take the readings?

Why do the old guys insist on flowing nitrogen through the lineset while brazing, and how much flow is right?

What's the accepted evacuation target and decay test before I release charge on a new residential split system, and where should the micron gauge be?

Do I charge R-410A as a liquid or a vapor, and why does it matter?

Customer says her AC 'isn't cold enough.' What temperature split across the evaporator should I expect and what does it depend on?

How do I actually verify airflow on a residential air handler instead of assuming 400 CFM per ton, and what static pressure numbers should worry me?

Why does an air handler with the coil upstream of the blower need a P-trap on the condensate drain, and how deep should it be?

I've got a condenser that has to sit 110 feet of line from the air handler, with the air handler 30 feet above the condenser. What do I need to think about beyond just running bigger copper?

Condenser fan runs but compressor just hums and trips. I suspect the capacitor. How do I test it and pick the replacement?

Heat pump customer thinks the unit is broken because it 'blows cold' and 'steams' for a few minutes on a cold morning. Explain what's actually happening and when it's a real problem.

Homeowner wants me to just replace his 3-ton with a 4-ton because 'bigger is better' in Florida. Make the case for doing a load calc instead, including what inputs actually drive it.

I'm laying out ductwork for a new 3-ton system. Walk me through how Manual D actually sizes the trunks and branches, in plain terms.

I've installed a new 80,000 BTU gas furnace. How do I check temperature rise and what do I do if it's out of range?

What manifold pressure should a natural-gas furnace run, what about propane, and what actually has to change to convert one to LP?

Doing a combustion analysis on a 90+ condensing furnace. What readings am I looking for and which number is the stop-the-job number?

Compressor pulls high amps at startup and sometimes trips. How do I tell a weak compressor from a start problem, and when is a hard-start kit the right answer?

I'm pulling the compressor on a 4-ton R-410A split. How far do I have to pull the refrigerant down before I open the system, legally?

TXV system is hunting - superheat swings from 3 to 20 degrees every couple minutes. Where do I look, and how should the sensing bulb be mounted?

Doing my first ductless mini-split. Any tips on the flares so it doesn't leak?

Putting an air handler in an attic over a finished ceiling. What does code require for condensate overflow protection?

In Florida specifically, is there anything extra on that attic condensate rule for a downflow unit or on the refrigerant service ports?

Installing a 100,000 BTU/h 80% gas furnace in a utility closet that's 6 by 8 feet with a 9-foot ceiling. Does the closet give it enough combustion air, and if not what do I need?

Where does the gas shutoff valve have to be for a furnace, and do I need a drip leg?

New construction in Florida with the ducts in the attic. What's the duct leakage test requirement and what number do I have to hit?

Can my helper buy a jug of R-410A and swap a condenser on his own house without a card?

Rules for putting a furnace or air handler in an attic - access, walkway, working space?

Electrician isn't coming back. For the condenser, where does the disconnect have to be, and how do I size the breaker and wire off the nameplate?

Tech is at a 3-ton R-410A TXV system on a 68 F afternoon in October. He hooks up gauges, sees 105 psi suction, says 'that's low for 410,' and starts adding refrigerant until suction reads 118 and the line is sweating. Subcooling is now 22 F. What did he do wrong?

New install: crew brazed the lineset without nitrogen, pulled a vacuum to 500 microns, charged by weight, and it ran great. Three weeks later the customer calls: system runs, suction line is frosting back to the compressor, then it goes to 45 psi and the coil ices. What happened and what's the fix?

Homeowner's condenser died on an older R-22 system. Contractor quoted 'condenser only' and is installing a new R-410A condensing unit on the existing indoor coil and copper, planning to flush the lineset. What's wrong?

Apprentice is pulling a vacuum on a new mini-split with a standard manifold set, both Schrader cores in, 1/4 in. hoses, micron gauge screwed onto the pump's inlet tee. After 45 minutes the gauge says 300 microns so he closes the gauges and opens the service valves. Next day the system is short on capacity. What went wrong?

Attic horizontal air handler: crew set it on a new 2-inch aux pan with a float switch in the pan, ran the primary 3/4 PVC out to the eave with a P-trap, put a vent tee between the coil and the trap, and tied the float switch into the R wire. Homeowner has ceiling damage six weeks later. Where's the error?

New 4-ton system, 1,600 CFM design. Installer ran 8-inch flex to eight supply registers, each run 25-40 feet, stapled to trusses every 6 feet, a couple runs make hard turns around the ridge. Return is a single 16x25 filter grille with a 14-inch flex run. Static pressure measured at 1.1 in. w.c. Where did it go wrong?

Jacksonville: 2,000 sq ft slab house, decent windows, attic ducts. Salesman sized it at 5 tons ('400 sq ft per ton plus a cushion for Florida') single-stage with a 5-ton air handler, no load calc. Homeowner is at 74 F on the thermostat but says the house feels sticky and the unit runs 8 minutes at a time. What's going on and what should have happened?

Compressor grounded out on a 3-ton R-410A heat pump. Tech recovered, swapped the compressor, replaced the liquid line drier, pulled a vacuum, weighed in the charge, and left. It ran 5 weeks and the new compressor failed the same way. What did he miss?

Gas furnace lives in a 3x6 closet off the hallway. Previous contractor cut a big return grille into the closet door and pulled return air straight from the closet through the furnace's open filter slot. Furnace is a standard 80% with a B-vent through the roof. Combustion analyzer reads 200 ppm CO in the flue and goes up when the door closes. What's the failure?