Troubleshooting and testing the HVAC contactor Part 7

Describing the different failures related to contactors used in heat pumps and air conditioners
If you are a homeowner looking to repair your own appliance, understand that the voltages can be lethal, the fuels are highly flammable and high pressures are used. Know your limits.

[natashamarie]

You just saved me a service call to an ac repair place. I cleaned the contactor and now I have ac again. Thank you

[Bubfd]

Plain and simple to understand, excellent presentation for a 70 rear old wannabe, never to old to learn, Thanks

[defroyh]

Thanks for this video.  I had a contactor that was welded closed so my unit never stopped and was all iced over.  Thanks to your video i was able to diagnose the problem, procure a replacement, install it, test it, and save a buck.  I really appreciate it!

[kellihunter]

Your video was perfect! I didn't even know what a connector looked like, but your video was clear and to the point, thank you! Tonight we'll be warm 😊

[rolandvz]

It was the breaker outside that feeds the unit...getting 240V incoming and w/breaker closed getting 120V. Replaced breaker w/one from a big box store and she is now off and running! THX for all the good advice!

[ivansilva]

You are a genius! Ant was crushed under contacts. Cleaned with a qtip and alcohol, started back up again. Surviving Texas weather. Thanks!!!

[ogpa]

Well you saved me a butt load of Thank you for taking the time to educate others. Not only was I able to determine the cause (a bug) I was able to learn about a trade I had not idea about. Thank you so much

[tjross]

Thanks for the great video. We've been without our air conditioner through the hottest part of the summer and with elderly house guests coming by often, it's been really hard on them. I put in a new capacitor and hoped that would start the thing up (the other one was confirmed dead with my multimeter), but that wasn't enough to get it going again. I've played around a little more and using a tester can see that all my wiring is live, so no problems there. I previously didn't look at the contactor in any way, but just tried to push in the switch and voila, it all started up which is a huge relief (I hope) because I was thinking it might be a bad control board, or my fan motor was shot, or maybe the float switch in my condensate pump was fried, or something worse. Anyhow, I guess I'm going to order another contactor and put it in there, hopefully that'll make the difference. I did use compressed air to see if perhaps I could clear some dead bugs from inside, but to no avail - it's still not doing anything.

[grayfurnaceman]

The contactor could be stuck closed. If the power is off to the low voltage, such as turning off the power to the furnace, the contactor is probably stuck. You can shut off the power to the outdoor unit, then manually break the contactor loose. The contactor then needs to be replaced. Hope this helps.
GFM

[grayfurnaceman]

If you have 24 volts at the coil and the bar is not pulled down, the coil is bad. If you do not have 24 volts, the problem is elsewhere. Such as: no 24 volt power, thermostat not closed, a possible low pressure control open, a loose wire. What you must do is measure for 24 volts at the source, then continue though the circuit until the voltage stops. Remember, there is lethal voltage here. Hope this helps.
GFM

[michaelgramling]

Thanks for the vid, I had been checking voltage using chassis ground all along (newbie).  Turns out it was just a fuse, what a relief, thanks!

[sietafak]

Great video! Just tested my contactor and 0 volts on the out side. When I first opened the box there were quite a few dead ants on there. Blew it with compressed air but no change. Got a $20 replacement, hopefully we'll be up and running soon.

[mikeraphone]

Great video, the pain you relieve in the summer time can't be underestimated, thank you.

[grayfurnaceman]

Ok. You have a refrigerant leak. The power is coming from the thermostat and when it comes to the board outside, the board looks at the low pressure switch, sees it is open and cuts power to the contactor. It is a safety switch to keep the unit from running if the refrigerant charge is too low. Look for oil slicks, especially around service valves. Hope this helps.
GFM

[lakai]

Thanks for the video. Probably saved me a few hundred. I had the bug stuck in the contacts.

[grayfurnaceman]

Sorry, your comment was in spam. That sounds like the fan is drawing too much power and the overload is kicking off. Did you replace like for like? You might also check to see if you wired it right. After it shuts off, check the motor for overheat. If you have an ammeter, clamp one of the fan wires (not the capacitor wire) and compare to the rating on the motor. Hope this helps.
GFM

[JakeB]

Over 9 years later and still helpful -- Fire ants really do ruin everything. I've got cool air again but I've ordered a replacement contactor because I didn't like how fouled the old one had gotten inside.

[sourkraus]

You probably don't need another "bug in contactor" tale, but that was my issue! I really can't believe it. My wife and kids weren't as impressed as I was, but that's OK. ;) Thanks again!!!!

[stuartmorris]

thank you so much for the diagnostic steps... mine was just a dirty contractor and it started right up.

[r.d.ontheroad-]

You just saved me a lot of money! Thanks, I do appreciate your help! Mine, I just tapped it a few times, it wasn't welded, but it took off! Thanks!