In this HVAC Training Video, I show How to Quickly Find Low Voltage Shorts with a Multimeter! Once you know where to look and how to divide the wiring, troubleshooting the problem can be done fast! Supervision is needed by a licensed HVACR Tech while performing tasks as Experience and Apprenticeship garners Wisdom and Safety.
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What setting is your multimeter turned to?????
Do you have a 24v trouble shooting card made up? Easy to keep the the truck.
Whoever wired by AC in the backyard was a jerk. It went underground for two feet to then go to the house. Underground were wire thumb nuts with corrosion probably increasing resistance but the wires were mist likely being hit by a weed Wacker and the copper was exposed. I can't believe I didn't see this that the wiring appearance should be perfect and not at all trying to hide underground for looks. Another $142 job.
You could have a dead short in the low pressure switch that will cause the fuse to blow when in cool mode
Do you have a video on how to replace the transformer?
Hello, If a compressor was recently replaced in January and not cooling due to low freon, and constantly running and trying to cool the house but the temp keeps rising, could this constant load of the compressor trying to cool with low freon for hours cause a disconnect to short out?
Easy way to do this quickly without making trips to the thermostat is install your popper fuse and unhook your wires. Leave your thermostat calling and hook them up one by one until it trips. Of course use your meter to verify your suspicions, but that’s a quick down and dirty way to find the problem.
Hey I have a question, when you check for resistance values you disconnect all wire at the board except common right, but do you also disconnect the wires at the thermostat ? Or you leave those connected?
Love your content. I work industrial HVAC for a plant 8,000 tons of cooling and forget the residential stuff sometimes. Helps with side work lol.
Why leave common wire in terminal when test the ohm reading ? Thanks
Great video
Where you get that magnet from?
Your vids are top notch and have helped me become a better tech for my customers and business partners! Thanks a million sir.
gas valve could be pulling to many amps as well
Ran into a problem where the breaker kept tripping every time the furnace came on ended up being the igniter wires melted together.
BOSS LEVEL!
Thank you so much testing with resistance is something I was struggling with seeing in perspective like this is an eye opener
I dont understand why when is reading OL thats not the problem. Is an open line.
Do this exact thing with a basic gas garage heater. I unplugged everything from the board and it still blows the fuse. I ordered a new board after running out of options.
I sure was hoping to see how you use that microwave donut magnet that was hanging by the door switch to override that door switch…LOL. 🙂
I had one today. The led was in standby mode. As I was testing I crossed W with R
Blow the fuse. But didn’t blow the fuse when
The thermostat called for heat . The furnace didn’t come on . As I was going through the troubleshooting I found it . The high limit switch was shorted to the frame .
Thank you sir 👍👍
To keep from making one million trips wire a T-stat to carry w/ you for the amount of wiring you need. You can use 2H/1C T-Stats for furnaces if you wire the W to your Emergency Heat in your diagnoses T-Stat. If it’s a Heat Pump set then just continue as the wiring should be applied. Attic trips are a killer, don’t forget your fuse pop switch so you don’t burn through fuses.
Nice ! Keep up the positive outpouring
I had a house on Friday where there with a 6 zone pneumatic zone control. After about 2 hrs of tracing a maze of wires, there were no marrettes on the humidifier, and they were touching the duct work. The ac low voltage wire was also bad inside a finished ceiling, and the R wire entering the zone control was broken and touching the case of the box. It was a mess.
I have a question about a blown fuse on an electric furnace on the heat side. I turn the furnace on and it will run for about 30 mins, then it shorts out the 3a fuse and the tstat is out. Replace the fuse and it does the same thing repeatedly. Is that due to a bad sequencer, or possibly a thermal limit switch ??
Thanks for the video =)
What happens when the transformer gets hot then dies but not blowing the fuse?
awesome
Hi Craig, my HVAC unit was not started and after seeing this video, I have checked the fuse and it was blown out. Then I replaced the fuse. The unit works fine in fan mode and heat mode. when i turned on the cooling in thermostat the fuse blew out again. Please let me know what could be the possible reasons and what else I can check. Please advice
Thank You !
Extremely Informative and much appreciated. Keep up the amazing work.
it is the best channel for HAVC systems … welldone man
I love and watch a video just about everyday..
If you have a heat pump it’s likely one of your pressure switches in the condenser wire jacket has rubbed through and shorting your ground on a copper tubing. Carriers are notorious for that I blame Mexico factory workers for lack of attention to details
i changed the thermostat and now nothing works except the blower… even without the thermostat connected to the board it stays on.
i have not blown a fuse or lost power in the main board.
The gas valve is a smart valve and power for the inducer motor is coming from main board to the gas valve but no power is going to the inducer from the gas valve, does that mean the gas valve connector/board is no good?
i checked the limit and rolls outs, all showing continuity with power coming and going.
The connector on the gas valve for the inducer motor is 4 wires.. black and white IN (which has power ) and black and white out ( to inducer having NO power) …is this a direct connection ? or is there something else that needs to be satisfied before power is sent to inducer?i trying to figure out if there is anything i didn't check