8 replies to this topic

[Fudge-Brownie]

I just charged my AC system the other day since I havent done so since the build. Anyways, I was getting nice cold AC for a few days until today when I had nothing all of a sudden. Other than the compressor the AC system was all replaced a few years back, but now when I turn on the AC the clutch isnt engaging all of a sudden. Would this be a relay issue?

Edited by dublin14, 14 May 2012 - 12:09 AM.

[burnout8488]

First, ensure the system has adequate pressure. ~44psi is the minimum pressure for the car to allow the compressor to engage.

If there are no leaks and an adequate charge (static (off) pressure should be around 80-100psi) then look at the clutch gap. Test: Turn the A/C to "on" and run the car, then hit the clutch with a broomstick or equivalent tool that will not injure you. If the clutch engages, it needs to be shimmed. If not, the clutch isn't getting the "on" signal from the car. At that point, I'd look to the relay, faulty low pressure switch, or ECC module in the dash.

[Fudge-Brownie]

Ill give it a shot and get back.thanks

[Fudge-Brownie]

That didnt work. So I might have a leak? I'll have to run a dye I guess and see where its leaking.

[erikv11]

I think not, unless you didn't understand what burnout8488 was posting?

The only reason to suspect a leak is if there is not adequate pressure. But you must have adequate pressure, since you need it before you can test the compressor clutch. And you just posted that you checked the clutch gap. So ... ? Maybe this was not made clear enough: The way to tell whether or not the AC has a leak is by checking pressure, with a gauge. Not by attempting to test the clutch gap.

So, if the system does have pressure, then try the other things mentioned. Will take some searching but the low pressure switch can be jumpered, for example.

[Fudge-Brownie]

I think not, unless you didn't understand what burnout8488 was posting?

The only reason to suspect a leak is if there is not adequate pressure. But you must have adequate pressure, since you need it before you can test the compressor clutch. And you just posted that you checked the clutch gap. So ... ? Maybe this was not made clear enough: The way to tell whether or not the AC has a leak is by checking pressure, with a gauge. Not by attempting to test the clutch gap.

So, if the system does have pressure, then try the other things mentioned. Will take some searching but the low pressure switch can be jumpered, for example.

I didnt check the clutch on the compressor to see if I had a leak? That would make no sense at all. I checked the clutch to see if it would engage with a tap.. and it didnt. Now Im going to check for leaks with dye and see if I have a leak

Edited by dublin14, 15 May 2012 - 01:51 AM.

[erikv11]

That's right, it would make no sense to check the clutch without first checking the pressure. Yeah I wrote more words than I need to ... I'll try again: I agree it might have a leak. But tapping the clutch is not the way to find out.

All I'm saying is you might want to first put a gauge on the valve and check pressure. If there is none, then dye test it. But if there is enough pressure, then don't waste your time with the dye. burnout's post explains it very clearly, it goes like this:

(1a) If there is pressure in the system and the clutch engages when tapped:
- removing clutch shims (or using zip ties) will solve it

(1b) If there is pressure in the system and the clutch does not engage when tapped:
- test the relay, the low pressure switch, or the ECC module in the dash.

(2) If there is no pressure in the system:
- Stop. Do not pass go. The clutch will not engage when there is insufficient pressure in the system. Ever. In that case, don't bother tapping it.

Since you didn't check pressure first, you don't know if the system is empty (2), or if the system is still charged but one of those other components is bad (1b). Is there pressure in the system or not? That's the first question.

You said AC quit working all at once, which is unusual for a leak. Usually craps out gradually, gets weaker. So some component failure is a reasonable explanation, too. Test the pressure and find out! On the pressure side, at least you know the evap should be OK since "the AC system was all replaced a few years back."

Hey did you evacuate the system before charging it? Moisture mixes with r134a to form acid, which will corrode the system internally. But I always thought that takes longer to happen.

[Fudge-Brownie]

Well thanks for the steps. I'll start form the top and hopefully get an answer. Over all the years and cars, Ive never had AC issues and never had to fix any AC system. Now its twice with the Volvo. First time the Evap went and now this.

Edited by dublin14, 15 May 2012 - 12:01 PM.

[burnout8488]

erikv11 you sure saved me a lot of typing

I've rebuilt the A/C system on my S70 from the ground up, painting the lines, replacing every part, and it's actually quite a simple system once you've worked on it a bit. Make sure you evacuate the system before recharging it if you need to replace something and lose all of your refrigerant. Ask any questions here, I'd be glad to help you.