Almost Overheated Today!!

[Sidewinder]

Driving home from work I turned on the AC about 5 miles from home. By the time I got home I had turned off the AC and the temp was reading about 3/4 on the gauge. Not into the red but that gauge has never moved above the 1/2 mark. I pulled into the garage and the fan was not running. I also heard this buzzing sound coming from under the plastic cover where the throttle is. I pulled the cover and there was I silver cylinder with 2 hoses and a wiring harness making the buzzing. (Sorry for the lack of technical description. I am new to Volvos ) The only thing that has changed is that last Sat. morning I changed the coolant and the hoses. But it has run fine all week in almost 90degree stop and go traffic without even the slightest problem. I would think that if there was an air bubble in the cooling system it would have gotten hot before now. Any suggestions where to look? Any idea what that silver thing is?

Thanks

[Free2drive!]

Judging by your description the silver thing is the 'idle valve'. Does the engine idle steady at 850-900 rpm? If yes then this is ok, and shouldn't affect the engine temp.

You may have an air bubble, check all the hose clamps for leaks and did you replace the thermostat? Do you have the gray cap or green cap on the expansion tank? Green is preferred but if its old it may fail.

Does the radiator fan run when the a/c is on? If the car is running hot the fan should come on, my suspisions if you have checked the above, lie with the rad fan - relay -sensor or wiring.

Hope this helps
Matthew

[Sidewinder]

The car starts and idles great. I do have a grey cap on the tank. I may need to order a new one it sounds. I have not found any leaks in the cooling system at all.

Odd thing is when you push the AC button inside the car the fan does not start. When it was running hot the fan was not running either. I drove my Jeep today so when I get home I will start the car without the AC on and let it idle until it reaches normal temp and see if the fan will start. Could I maybe have a bas fuse or relay? If so which ones would I check and how should I test them. Fortunately my local junk yard has 2 850's. One Turbo and one Non-Turbo. They are pretty cheap so I can afford to just get some parts and swap until it works if I know what to get.

[Ozark Lee]

If the fan is not coming on along with the A/C then chances are you have a bad fan relay or possibly a bad fan. There is no fuse in the fan circuit, it uses a fusible link.

The fan is easy to test. Just jumper between the 2 red wires on the fan relay and the fan should run. You can do that with the key off.

...Lee

[Sidewinder]

I jumped the two red wires tonight and nothing happened. I tested the power and there was power there. Sounds like a bad fan to me thanks for the advice. I will round one up in the junk yard this weekend. There is not any difference between a non-turbo fan and a turbo fan is there?

Thanks

[MadeInJapan]

VADIS shows that the turbo fan is a 2 speed fan and has a different part number than the one which is only one speed for the non-turbo. What you want is part #9497929.

Edit: Well, the number above is for a '96-'97 fan. I just found where the part number for '94-'95 turbo fan is #3507197. I have no idea if they are interchangeable or not.

[Sidewinder]

Ok I figured it out so I thought I would share the results.

I did a lot of testing. I removed the fan from the car and tested it on the bench worked fine. I put it back in the car and turned on the AC and the fan started running. I took it for a spin and it started getting hot again. I took it back to my home shop and bench tested the fan again DAMN HOT but the fan worked fine. So I started testing the terminals on the fan relay. It looks like the relay would work fine while it was cold but after having a constant like the AC it would overheat and stop working. I replaced the relay and it drove 30miles with the AC running in 90degree heat with no issues.

So far so good