[BigEHead]

Thanks for reading. My nest was working fine until this season when it said I didn't have any power going to the Y wire (i didn't have a common). Everyone said you just need a common wire and it'll work. I added a common wire, and the nest says it's fine, but when i call for cooling the compressor doesn't turn on.

I tested the wires at the compressor coming from the transformer, and i'm getting 24v when calling for cooling. When i test the contactor low voltage terminals, i'm not getting any voltage. I believe the wires that come from the transformer go to the lps/hps first? so i'm assuming that the low pressure switch or high pressure switch (i'm assuming lps though) is tripped. When I plunge the contactor plunger, it does activate the compressor. Am I right to assume that it's the lps? If so then i think i probably need an r22 charge.

Thanks!

 

[surferdude2]

If the low side pressure switch is open, it's either defective or the refrigerant charge has leaked out. The latter is most likely. You will need to repair the leak before recharging the system. R22 is very expensive and recharging the system every season will be painful, fixing the leak is the answer.

Fix it yourself, if you are equipped for that kind of work, or call for help. A jug of R22 costs more than it will to get a tech to fix it for you.

 

[BigEHead]

Thanks!

 

[57TinkerMan]

You may have a high pressure cut out switch with a manual reset too. Not all units have these. Worth a try though.

 

[BigEHead]

ah right, will check that out as well. thanks!

 

[BigEHead]

So my high pressure switch doesn't have a manual override. i would need to test the voltage coming from both hps and lps to see which one isn't passing voltage through right?

 

[BigEHead]

I guess continuity makes more sense...

 

[BigEHead]

So apparently there is a leak. Not sure where. The HVAC tech said he could recharge but he recommends putting in a sealant which could potentially close pinhole leaks. My unit is pretty old so it's not like I'd void the warranty. Do you guys recommend using a sealant?

 

[roughneck]

I don’t like leak sealant nor do I recommend it, on anything other then old units that nobody cares if they live or die.
If there’s any atmospheric products within the system, it will cause the sealer to harden within the circuit and kill the system.
If you use it you must also replace the lineset when new equipment is installed.

 

[surferdude2]

Placing anything other than the proper type of refrigerant is considered contaminating the system. It's a form a chemical warfare on the sealed system... every part of it.

Find and fix the leak... if that's impossible, you might as well face the music, that unit will cost more to maintain than it's worth. Not only that, if it completely loses its charge a few times, it'll get contaminated with O₂ and H₂O which will destroy it internally due to acid formation so the end is already in sight. With a leaky system, it can't be evacuated properly and will always be contaminated and doomed for failure