96 850 wagon. Start car up, runs fine temp in proper range then after about 5 minutes or so the gauge begins to climb fairly rapidly into the red zone. Comes down to some extent while driving but hangs pretty high.
System has been checked for air pocket. Ok.
new thermostat. no change
fan speed steps up as it should
An instant after temp gauge starts up the a/c compressor cuts out. freon levels seem ok. Blows cold. not overfilled
Strange that as a/c kicks out that temp would go up. Hot wiring a/c compressor to battery changes nothing as far as temp.
If I let car cool down for a few minutes a/c works for a little while and then cuts off
bottom line is it runs just fine with the temp gauge in range the inexplicably shoots up and hangs.
Any ideas?

Thanks, Derek

 

Wonder if your temp. sensor in the reservoir is going or is shot! That's an easy thing to replace. Normally when the thermostat is replaced, most Volvo shops replace that sensor also. I changed out my thermostat when I did the waterpump, and the gauge started doing the same thing. http://www.fcpgroton.com/product-exe...category_id/88

 

symptoms sound like a bad thermostat... i know its a stupid question, but did you put it in the right way? if you put it in upside down or something that could maybe do that.

other than that possible a clogged radiator.

worse case, bad water pump, but then usually you will head a squeal or something.

 

I have also seen brand new thermostats fail also!..... See if the one you have went.

 

Headgasket?

 

if its his head gasket he would be losing coolant and/or have coolaint in the oil making the oil milky.

 

Not always.
Sometimes it will just loose a little bit out of the cap on the bottle.

 

Thanks for all the input. One additional point to make sure it's clear; the car warms up and acts fine for a short while then it starts shooting up.
The sensor sounds like a good idea. I'll check it out. Head gasket? I don't think so. Engine runs strong.
I'll check those things out and get back.

Thanks again, Derek

 

I tried boiling out the radiator as kind of a last resort and it still didn't fix it. Was a little better though as I guess it needed it but the problem ultimately was a bad new replacement thermostat as one guy suggested. Went through a lot of runaround to arrive at that but at least it's over.

Thanks to all who contributed and for having this forum.

Til next time,

Derek

 

Glad you solved the mystery!

So where did you get the original thermostat (the one that failed)? Was it OEM?