Ok, I got a mess of parts to try and fix my AC system. Last summer I had the AC compressor replaced (new, not reman) plus I had the dryer replaced at the same time. I was about to do some work on the thing and when I try and turn on the AC, the compressor doesn't even enagage now. Turn on the engine, flick the switch for AC, turn on the blower, nothing, nadda. Why? No codes thrown, no rec/ac flashy lights, just a compressor that doesn't enagage. It worked fine not too long ago, just cycled all the time due to a leak. Any thoughts before I lose it?

 

OK, did you replace the evaporator? The original evaporator is guaranteed to fail, and if R134a (freon) has escaped out of the system, the compressor wouldn't engage.

Check the system pressure to see if there is sufficient R134a in the system. If there is, the problem may be as simple as a blown fuse, but if there is not much pressure, you need to replace the evaporator with an aftermarket unit (genuine Volvo unit is the one that fails).

I hope this helps.


JPN

 

Evaporator, no. I'm almost sure that the guy who owned it before me did so. This is what I want to check though, I want to see exactly where the leak is before I take the time to replace it and so I got that 134a with dye in it. However, if I can't get the compressor to cycle, I can't add it, correct?I checked the fuse in the engine compartment (25a) and that was fine; is there a different one I should check?

 

Hi,

If the leak is somewhere else, it is usually around connections (tubing, receiver/dryer, condenser, compressor, etc...). I would black-light those areas. If black-light is not available, you can check to see if there is a thin film of PAG oil, the oil that is recirculating in the system, mixed with R134a.

I would use an aftermarket recharge kit that has pressure gage (most of them do I believe, and the gage often has colour-bands to indicate correct pressure). As you probably know, these kits are available at many auto parts stores, or even at Wal-mart.

Volvo manual states that the correct pressure is between 25-33PSI, on the low side, and I believe a recharge kit has green arc around the same range.

I've attached another possibility to check, which is AC relay. However, if it was the relay, then it should have triggered some codes so this may have nothing to do with the problem so just a reference. If the compressor was working until recently, I am 70% sure that the system is low/empty of R134a. So, try a recharge kit to see if the system has proper amount of R134a, or have a shop check it, if it is less expensive to do so.

EDIT: I'll delete the manuals within the next 7 days so make sure to save them in your PC.


JPN

 

DAMN! I just replaced the stupid blower resistor ... I could have checked the relay at the same time! That glove box is a pain...

Thanks for the diagrams - the AC charging hose I have is VERY similar to the one pictured, so I think I should be ok...

I understand about the compressor not cycling if the pressure is too low, but if the compressor doesn't cycle, how can I add r134? I was under the impression from everything I read (mostly my Haynes manual) that the compressor needs to be, uh, compressing (or otherwise on) to charge the system...

Last I knew, the compressor was fine - I remember it cycling last summer, but obviously never used it in the winter (I live in the north, only 3 hours from Canada) and never turned it on this Summer until recently because I knew it needed a charge so it wouldn't work anyway. There are only 2 wires going to the compressor, right?

Is there a simple way to just check the evaporator without dismantling the entire car?

 

Hi Dads850,

>That glove box is a pain...
Agreed. Torx screws keep falling into the deep abyss of the dash, the arc-shaped lid arms keep falling into the narrow gap, etc.... Well, it may not be the relay and I feel it is probably ok.

The AC compressor does not turn if the system is absolutely empty. So, first thing you can do is to charge the system with a kit anyway, with the AC on at the coldest & fastest blower setting. However, please note that my knowledge on AC is based on general learning, so double check on this procedure with either other members here orwith Haynes AC manual again. Make sure to service from the LOW side. The compressor would be damaged if serviced at the high side, especially if liquid form of R134a is introduced; this induces liquid lock in the compressor and causes permanent damage. Or better yet, visit an auto AC specialised shop and do complete leak test, evacuation & recharge of the system.

The most popular cause of AC failure is not being used in winter. If not used during winter, the O-rings at connections dry up and Freon escapes from there. So, it is a good habit to run the AC at least 10 minutes/week in winter. You can use heater with the AC on so you won't freeze your gluteus maximus.

>There are only 2 wires going to the compressor, right?
As far as I remember, yes. But again, double check to make sure. Some members here have worked on the compressor recently and they can give you better answer than I could.

>Is there a simple way to just check the evaporator without dismantling the entire car?
Not that I know of. But if you don't see thin film of oil anywhere on the AC line, chances are that the evaporator may be leaking. But I would first call the previous owner to see if he actually did replace it. If not, the evaporator is 99% shot.

I hope this guides you in the right direction.


JPN

 

With the engine off, can you hear the clutch engaging? Just for testing you can bypass the low pressure switch close to the firewall.

 

JPN: everything you've said has helped get things started

axelm: No, I do not hear the clutch engage at all, nor do I see it engage. To bypass the switch, do I just unplug it or do I short (jumper) it?

 

Remove the plug and use a wire to jump both pins. That will tell the ECU that the pressure on the low pressure side is fine.

Read my A/C nightmare thread here: https://volvoforums.com/m_48510/mpage_1/key_/tm.htm

Regards

 

Ok, I'll keep that in my head for reference.... Funny thing, for the hell of it, I tried it again today at lunch and the thing started cycling! NO idea why it's working now... Anyway, I added about 1.5 cans of r134 with the dye and the gauge is reading around 35psi now. I'll run it like this for a while and see if I can find a leak. At least I had AC getting back to work as it's in the mid-90's and HUMID today. They're saying the heat index is 102ยบ :\