Hi. I dug around and I'm not quite sure what I'm looking for.

Here's a brief history. We bought a 95 850 turbo coupe that seems to have an a.c. problem. The guy we bought it from said he had a problem with some sort of switch and by passed it or jumpered it or something and ended up frying the compressor. He had a mechanic put in a new compressor and still had trouble. this was two years ago and the a.c had worked intermittent I think. that's when we bought it and just now decided to try to get it fixed.

So we take her in for an a.c. service and the shop says it needs more than an a.c. service (OH crap, I vaguely remember the p.o. saying something about switches and compressor etc...)

Anyways, he says that the system is overcharged and he evacuated and recharged to spec. He says that the compressor kicks on and then shuts off. You restart and it kicks on and then shuts off again. Blower keeps blowing. He says the clutch is fine and they checked it at 23 thousandths(???) and with some one going in and jacking around with it, we might want to take to a dealer to sort out. He charged us an additional 1/2 hour labor and threw in the towel.

So I test it and the air is coldish for a few seconds on start up and then the two lights by the recirc and a.c. switch start flashing for about 10 to 15 seconds as the coolish air gets warmer and warmer. It never gets totally cold, just on it's way there and then stops blowing cold.

I'm thinking if it were shimmed wrong, it wouldn't even kick on to begin with. Mechanic said that if they jumpered something, they could have messed up the control module or any number of things.

The closest volvo dealer is over 2 hours away.

Maybe these symptoms sound familiar or someone can give me a clue as to which switches were bypassed and how to check if the switches or control panel or something else is wrong?

This may be beyond my mechanical abilities but I hope not. I don't have the obd1 tester or what ever it takes either and I don't think autozone has one either.

I sure don't know where to start???????????/

 

Left you answer on other tread
https://volvoforums.com/forum/volvo-850-16/c-does-not-cool-good-when-hot-31761/
Not sure but I think only Volvo scanner can diagnose A/C not generic OBD scanner

 

Well, checking under the hood, It sounds like the ac compressor is kicking on for about 10 seconds then off 10 then on 10 and so on but the cool only comes briefly when the car is first started. I don't know if the ac compressor can be on with the clutch disengaged or not. I've been trying to hunt down something that actually shows how the clutch works.

 

Does the cooling fan kick in when the compressor runs?
If not you might want to start with a new High pressure switch.

 

I'd sure like to throw a part at it , especially if it's a low price part heh heh. I need to figure out where this switch is.

 

The switch is attached to the piping right behind the passenger side headlight.
Maybe see if you can find a used one to try.

 

I priced the new ones at $72.00 + so I'll try to see if a junk yard has a volvo (fat chance in this area) with the part. It looks like the volvo part number is 9132754 and if I do find one, hopefully it's a properly functioning one. Do you know what all year and makes are compatible?

 

I think the 95 and up 850's to 98 maybe 99 S70 are the same.

 

Having trouble finding the part at the junk yard and someone suggested jumpering the two wires at the switch to see if the ac comes on blows cold and stays on which would say the switch was bad for sure.

Problem is that when I unplug the socket on the switch, there are three prongs from three wires. Its an an angle but you could say the prongs are left to right. Any idea which wires I would jumper to test?

I also see that the switch will unscrew with a 13 mm wrench and the parts yard has one for $20.00 condition unknown and I pull. If I unscrew the one from my vehicle to replace, do I loose all the freon and will I need a new o-ring or anything?

 

Those are a pain to jump because you need to jump the 3 wires but I forget which way.
One is a ground the other is the A/C feed and the other is for the cooling fan basically you need to jump both the A/C and fan ones.

You will not loose any freon when you remove the switch. Well there is a really tiny bit almost like when you try to fill your tire for a split second there is a tiny pssst when you put the hose on.But it is not any amount to worry about. It will happen when you pull the switch off.

 

O.K. after a trip to the salvage yard for the high pressure switch, I've switched the switches out. Little green oil and a hiss and some carb cleaner to clean the mess. Still not working. I also picked up a low pressure switch but not installed. Not sure if it would do anything since I don't know what the purpose of the low pressure switch is.

I vaguely remember the gap on the clutch needing to be 16 to 20 thousandths and the shop here telling me "it's ok. it's right at 23 thousandths where it's suppose to be"

How would I confirm that and it seems I read somewhere that you can shim it on the car? How would that be done if it needs shimming? Is there anyway to force it to run and confirm that it's all in a lack of shims?

Sorry for all the questions but I lost my job so I'm kind of stuck trying to do this myself as cheaply as possible. Thanks in advance for all the help. -Adam

 

You can add power directly to the compressor with the car running to test the compressor. .025 is the max it should be. The Min is .015.
Also unplug the low pressure switch and install a wire in the plug to test if the sensor is bad. If the system is low on pressure the switch stops it from coming on.

 

does your CCM inside the car have an auto setting? If so your lights are most likely flashing cause an inside temp sensor is bad. that's no big deal mine does it too. usually at .023 an 850 clutch will not disengauge but it is always possible. usually a clutch has to be out about .030 too short cycle. and yes you can shim the clutch on the car but they're not too much fun

 

one more thing when was the evaporator replaced or is it still factory?

 

Not sure the evaporator was ever replaced. If the system is full, would the evaporator cause the compressor to kick on and off? This system was charged just before we bought it two years ago. Kind of worked when we first got it but my daughter has been driving it and didn't complain much. My wife drove it a couple times and said it wasn't working at all. We took it to be serviced when they discovered an overcharge and drained and refilled it. Whether the evaporator is good or not, I don't know. I just know that the system has not been leaking.

I added some shims from the outside to see if it helped. I shimmed it probably a little too tight. It still turns by hand with out rubbing when the vehicle is off. Probably 2 to 4 thousands. Really close but like I say, it turns freely so I don't know if it will hurt anything since it doesn't seem to be dragging.

When I start the vehicle, same difference. The fan in the car remains blowing hard but the compressor kicks on and then off and then on and off..... It is on for about a second or two and then shuts off for a few or more and then on for a second or two, maybe more, and then off again. Replacing the high pressure switch seems to have stopped the lights from flashing. That's about it. It may be a bad switch though (from a junk yard you know).

I read something about the other switch down by the compressor maybe jumping past it to make the compressor stay on all the time. Or something like that. If I could get the compressor to stay on long enough, it might blow cold and that might tell me something, not sure what.

Maybe I need to do this when I'm drunk, I've had better luck that way.


Adam...who has currently racked his brain all he can for the day...

 

The way it is acting is like it is low on freon. Did you unplug the low pressure switch and jump it to see if it will stay running? If not try that.

The switch on the compressor is a overheat shutoff switch.

 

Thanks for your input.

If it is low on freon, the shop may have filled it to the wrong pressure? They just had it in Friday to evacuate and refill and it still didn't work.

When I jumper the low pressure switch, Do I jumper the plug or the switch and should it keep running with the switch jumped?. I have an extra low pressure switch to throw on as well if it would help. Maybe good, maybe defective, not sure.

I'm not sure what to expect when I jumper it and what it all means. I could also try adding more freon on top of what they put in or do I stick a guage of some sort to measure pressure somewhere? They say they filled it to spec which I think they said 2.7 something but I have no way of verifying it that I know of.

Adam

 

Jump the plug to the low pressure switch and start the car and see if the compressor keeps running. If it does it is either low or the pressure switch is bad. I would not leave it running all that long just jumped.

Also if they filled it to 2.7 it is way overfull. The system holds 1.63 LBS.

 

O.K. I just put a jumper in and the compressor kept on running. Inside the vehicle, I couldn't tell if it was blowing extremely cool but it seemed too. Not exactly sure since it's about 75 and humid after a rain this morning. I left it jumped for a couple minutes. Kept running.

The shop that recharged didn't specify how much they put in on the paperwork. I don't know if they could have under filled or over filled but if there is a way to put a guage somewhere, I would try to see. I could also buy a kit to put more in but I don't want to chance overfilling + I never did one of the kits.

I put my spare low pressure switch on and it does the same thing as the old one. I'll check an auto part store to see if this switch is cheap and available new.

What would be my next step, try to check pressure and if so, how?

Or do I wait till tomorrow and see what the place that recharged it has to say?

We've determined a bad switch or low freon we think.

-Adam...who absolutely hates heat waves but is o.k. with 75 and humid

 

Well that is exactly what you narrowed it down to. Either low on freon or bad switch.
And I would stick more towards the low on freon side since when you jumped it the air was not ice cold. If the switch was bad and you jumped it then it would blow cold.

If it were me I would wait till tomorrow and see what the shop has to say.
If you can I would also watch when they put freon in and make sure it is the proper amount. Remember it is supposed to hold 1.63.