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Car Forum / Volvo Cars / July 20071996 Volvo 850 Turbo with A/C problem
Okay it doesn't appear that my a/c is losing refrigerant. As best as I can diagnose the problem here is what I have come up with: When I start my car the A/C comes on and some times it will stay on for hours. Other times it will only stay on for 10 minutes. When I turn the a/c off 10 minutes and then back on it will work fine. But at some point it may go off again. The vent continues to blow but it feels like it is burning outside air. The air is no way cold. When I press the a/c off/auto switch I can hear the engine idle differently which indicates the compressor is kicking on and off but only hot air comes out of the vents. I am not sure if it is a compressor going bad; a loose wire somewhere or what? Help!!! It is 90 degrees here. I don't have the money to take it to Volvo. I was thinking of letting this independent mechanic take a look at it. Thanks DJ > Okay it doesn't appear that my a/c is losing refrigerant. As best as I > can diagnose the problem here is what I have come up with: [quoted text clipped - 18 lines] > > DJ Can you see whether the compressor clutch is kicking in? It could simply be low on refrigerant, you may want to take it to an AC shop, definitely don't go to the dealer, the car is too old for that to make sense, they're only really good for fairly new cars that are under warranty. > Okay it doesn't appear that my a/c is losing refrigerant. As best as I > can diagnose the problem here is what I have come up with: [quoted text clipped - 18 lines] > > DJ About 2 years ago my '96 850 definitely had evaporater leaks and I had it replaced. A couple of months later I had the "pressostat" switch fail. This happened when it got hot. It's located just above the exhaust manifold on the low pressure refrigerant return line, on the fire wall. The return refrigerant keeps it cool when it's running. When I stopped the car, even for 5 minutes, it would heat up from the exhaust, and the a/c no longer work when the car was re-started. It is mounted on a "schrader" valve and there is no need to de-gas and recharge if you replace it. A couple of months after that I had the compressor "overload" switch fail. Cooling suddenly ceased. This switch is mounted on the compressor itself and can be bypassed by simply by changing the plug and sockets around. Access is quite tight, for my hands anyway. Note the overload switch is not the diode mounted on top of the compressor, but is fitted in series with the compress clutch wire. From what I've read the overload switch fails quite regularly and is not used on later Volvos. I have run without it since then and have had no further problems. From your fault description, I'd try bypassing the overload switch first. But if you have both problems, you will find the symptoms very confusing. regards Barry > Okay it doesn't appear that my a/c is losing refrigerant. As best as I > can diagnose the problem here is what I have come up with: [quoted text clipped - 18 lines] > > DJ Start by checking if the compressor goes on and off for real or it only feels like it, easy to see by looking at it. If you have problems when its real hot i would guess it could be the clutch distance thats to big. You can measure the distance between the clutch and the wheel with a feeler gauge. Greetings Niels > Start by checking if the compressor goes on and off for real or it only > feels like it, easy to see by looking at it. > If you have problems when its real hot i would guess it could be the clutch > distance thats to big. You can measure the distance between the clutch and > the wheel with a feeler gauge. When you say check if the compressor goes on and off, do you mean it should go on and off in a cycle or should it stay on as long as the A/C is turned on ? -- Brian Sørup Volvo V70 2,5T Aut. >> Start by checking if the compressor goes on and off for real or it > only [quoted text clipped - 11 lines] > Brian Sørup > Volvo V70 2,5T Aut. I mean check whether the clutch engage when it feels like it or it fails because of to big clutch distance. Normal operation is it cycles on and off. Greetings Niels > > When you say check if the compressor goes on and off, do you mean it > > should go on and off in a cycle or should it stay on as long as the A/C [quoted text clipped - 6 lines] > because of to big clutch distance. > Normal operation is it cycles on and off. thanks, then my clutch is OK - but I think I need my A/C serviced since the air coming from the ducts doesn't feel very cold. -- Brian Sørup Volvo V70 2,5T Aut. > thanks, then my clutch is OK - but I think I need my A/C serviced since > the air coming from the ducts doesn't feel very cold. > -- > Brian Sørup > Volvo V70 2,5T Aut. That sounds right to me - some leakage is normal over ten years. I've learned not to mess with R134a myself and only recently learned why it has kicked my butt in previous attempts. I always recommend professionals for that. Mike Well I am taking my car to a mechanic tomorrow. He doesn't specialize in Volovos but I am hoping he has enough experience to troubleshoot and fix the problem. I don't know how to check the clutch. I know that when I first get in the car the air blows cold. Then it seems like when I change the fan speed it occasionally stops cold air from blowing. The vent still blows air but it isn't cold. Then if I turn the a/c on and off I can hear the compressor going on and off but the air doesn't get cold. But if I turn the a/c off from around 5 mins. and then back on the air will get cold again MOST of the time. Before the air never seemed to get cold so I had a guy put some freon in the car. Then it got colder as he was adding it. But I recall him saying something about my compressor may be going bad because I guess the guage on his device wouldn't go up to a certain number. He didn't check the car for leaks. But the air was cold and as I drove 10 mins from his shop the air wasn't cold anymore. > Well I am taking my car to a mechanic tomorrow. He doesn't specialize > in Volovos but I am hoping he has enough experience to troubleshoot [quoted text clipped - 14 lines] > check the car for leaks. But the air was cold and as I drove 10 mins > from his shop the air wasn't cold anymore. I can't imagine why a tech would add refrigerant to a system and not bother to check for leaks. It sounds like either the compressor has failed, or the refrigerant has leaked out again. Once it starts leaking it usually leaks pretty fast. >> Well I am taking my car to a mechanic tomorrow. He doesn't specialize >> in Volovos but I am hoping he has enough experience to troubleshoot [quoted text clipped - 19 lines] > failed, or the refrigerant has leaked out again. Once it starts leaking it > usually leaks pretty fast. I agree about the technique - not up to even minimal standards for charging R134a. My son's system took me to school last year and I decided the stories were true: R134a systems should be charged only by completely evacuating, leak checking (verifying the system holds the vacuum) and filling with the prescribed charge of R134a. The whole story can be found at http://www.autoacforum.com/ and the details of what it takes to charge by guage are in this part of the site http://tinyurl.com/2gvdaa . Apparently the environmental wind tunnel can be replaced by a whopping fan pointed at the condensor and allowing more time for the system to settle out... looks like about 15 minutes per ounce added. The time element - several hours of settling in the course of any meaningful recharge - makes the weight method the only practical method. Mike Ok I took my car to a mechanic and he said he hooked it up to the computer and the computer told him to clean the asperators. He said that it was clogged. And he charged me $90 to clean it out and reset the computer. He said there were no other error codes coming up. Well the a/c worked all that day. Then two days later I was driving with the a/c on and around 30 minutes into my trip I changed the fan speed from AUTO to a lower speed and the air was no longer cold. I told the a/c on and off; changed the fan speed back to AUTO but no go. Then when I got in the car later the a/c began to work fine. I drove for an hour and changed the fan speed and the air stayed cold the entire time. damn this is driving me nuts. Now I am out of $90 - not to mention the other money I spent for the guy to add freon. The freon doesn't seem to be leaking because I had it added over two months ago and it still gets cold when the ac is on. > Ok I took my car to a mechanic and he said he hooked it up to the > computer and the computer told him to clean the asperators. He said [quoted text clipped - 12 lines] > seem to be leaking because I had it added over two months ago and it > still gets cold when the ac is on. Barry 'baz' mentioned the notoriously troublesome over-temperature switch on the compressor of early 850s... I think yours qualifies. The ultimate solution is to bypass the offending switch - somebody here must have a link to a pictorial. The switch was supposed to be protective but in reality it was only a nuisance. Mike On Jun 21, 11:15 pm, "Michael Pardee" <michaeltn...@cybertrails.com> wrote: > <djisf...@gmail.com> wrote in message > [quoted text clipped - 24 lines] > > Mike If someone has a link to a pictorial on how to bypass this thing, please let me know. Thanks everyone for all of your help. May this be the last used car that I will ever buy. > On Jun 21, 11:15 pm, "Michael Pardee" <michaeltn...@cybertrails.com> > wrote: [quoted text clipped - 35 lines] > Thanks everyone for all of your help. May this be the last used car > that I will ever buy. Here's a brief description http://www.brickboard.com/AWD/index.htm?id=1089111 I can't find any pictures, but it apparently isn't as hard to find as it is to get to. Mike On Jun 22, 5:30 pm, "Michael Pardee" <michaeltn...@cybertrails.com> wrote: > <djisf...@gmail.com> wrote in message > [quoted text clipped - 45 lines] > > Mike Mike thanks... I found more detailed info with a photo here: http://volvospeed.com/vs_forum/Ac-Thermal-Switch-t76833.html Now that I feel pretty confident about what is causing the problem, I will let someone fix the clutch gap and maybe cut the wire. I have a very good Volvo mechanic here but he charges $85 an hour. Damn I wish I was earning that much an hour then I could afford to hire him. I am going to post a message on the board to try and find someone who is more affordable. Just want to let you guys know that I appreciate all of your help and your research! This site is awesome!! David > On Jun 22, 5:30 pm, "Michael Pardee" <michaeltn...@cybertrails.com> > wrote: [quoted text clipped - 64 lines] > > David When I bypassed mine ('96 850), there was no need to cut and splice. The existing connectors, although not identical can be plugged together to bypass the switch. I did my over 18 months ago and no problems. But it's a very tight spot to reach from above, like I did, just make sure everything is cool first, so you don't burn youself. It only takes minutes to do. regards barry > -- > [quoted text clipped - 93 lines] > regards > barry Well, I just went out and connected the white connector to the brown (or was it black) connector and the a/c came on so that is a good thing. Now I just have to wait for another very hot day to turn the a/ c on and run it all day to see if the problem has been resolved. :) David |
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