A/C Thermal Switch

jk1145 · Post by **jk1145** » 11 May 2010, 15:27

I think I have finally figured out what's going on with my A/C system. When I first bought the car the a/c would cut out and then never start again, did the ghetto clutch shim fix and worked perfectly till it started to really get hot outside. Now the Air cuts off about 10 minutes into driving and it won't start cooling again till the car has cooled off. I looked at the top of it and their are two things on it, and I'm not sure what is what. Also how do you bypass the thermal A/C Switch? (I read several other articles on here about it, but they confused me, any help would be great) Attached is a pic.

Post by **Ozark Lee** » 11 May 2010, 19:24

There are two wires that are associated with the thermal switch. If you want to bypass it just cut both of them and splice the wires together directly. Crimp style butt splices are quick and easy but I prefer to solder the wires together and then seal the joint with heat shrink.

...Lee

PerthX · Post by **PerthX** » 15 May 2010, 14:27

Any chance anyone can show me a picture of where those thermal switch wires are on a 95 850 turbo...seems like that may be the answer to my a/c issues too.

jk1145 · Post by **jk1145** » 16 May 2010, 13:24

Sorry I haven't replied sooner. I just got my new laptop charger in the mail so my comp has been down. I know how to splice the wires, I just am not sure where I need to splice them at. They seem to be coming in and going several different directions.

Post by **Ozark Lee** » 16 May 2010, 22:02

In the picture on the original post the bottom arrow points to the thermal cutoff switch. Snip the wires on both sides of it and then splice those wire together. It may or may not fix your underlying A/C problem if it is a clutch gap or R-134A charge problem.

...Lee

PerthX · Post by **PerthX** » 17 May 2010, 17:11

Before I go cutting wires or doing the shim sham dance, I am gonna try the $8 replacement relay mentioned by marginal
in his post A/C problem, the cause was the A/C relay......once I get it and try it, I'll report back.

jk1145 · Post by **jk1145** » 22 May 2010, 21:40

Thanks, so as the bottom arrow indicates that cylinder object, I cut the top wire and the bottom wire and then splice or solder them together, correct?

I'm honestly not sure which problem it may be. I will try and get my hands on that A/C Relay first before I start hacking wires. Sometimes I can drive for hours and the A/C will blow cold the entire time, other times it will work for 15 minutes quit. If the a/c switch is shut off it will work again after about three minutes to five minutes. Sometimes it does this all day, sometimes it doesn't happen for a day or two. It's kind of stumped me. This problem didn't show up till a few weeks after I had the unit charged, as soon as it started happening I took it back and they checked the freon. When running it was at 40 PSI.

Post by **Ozark Lee** » 23 May 2010, 11:55

You likely have a clutch gap issue - tis the season for it.

https://www.matthewsvolvosite.com/forums ... c&start=20

...Lee

jk1145 · Post by **jk1145** » 26 May 2010, 22:57

New developments. I've paid close attention to how my a/c has been working. For the past several mornings (Mid 70's) my a/c will work for the first 10 minutes then quit, when it quits, my temp quage is I'd say only 1/4 way up.. I shut the a/c switch off. Let it alone for 5 minutes by this time the temp quage was in the middle. Switch it back on, had cool air for the rest of my drive.

When I first bought the car the A/C would only come one time, after that no matter what you did it wouldn't come back on until the car was completely cooled off and restarted. I did the "ghetto clutch shim" and it worked flawlessly for about a month and then these problems started developing. The first day it messed up there was a loud "pop" inside the cabin. With the radio on it sounded like it came from the lower passenger foot area. Not a minute later the air became stale, and I shut the a/c off. After a few minutes I turned it back on but it still wouldn't come on. I switched it off for the remainder of our drive. Later on we get back in the car to go home and halfway home it just cuts out again. I was a little aggravated with it at this point, we got off the interstate and sat at a red light. I punched the gas and when the RPM's got just above 3500 the a/c kicked on. I have noticed that if it goes off, after a few minutes if I wind the RPMS(only works while in gear and moving) up to at least 3700 the a/c compressor will kick back in. This doesn't work all the time. Maybe 40% of the time. Since the first "pop" there haven't been any recurring ones.

Do you still think this could be a clutch gap issue? What tool would be used to check that? Thanks for your help!

jk1145 · Post by **jk1145** » 27 May 2010, 14:33

You are right, today when the a/c stopped working I used a board to push the clutch in and ta-da! Cold air. I'm going to get under it tonight. I'm wondering if my "shims" fell out as it worked perfectly fine for a month. If they are still in there I think I'm just going to have the compressor replaced. Thanks again!

Justin