I think I finally figured out why my AC only works for a few minutes unless it is extremely hot (95 plus degrees) outside.

My low speed cooling fan does not run but the high speed works. I have read the high speed runs if the radiator gets too hot, and since it works the engine never has any heat problems. The low speed is supposed to run whenever the AC is turned on. My guess is when it's super hot the high speed fan is running and therefor the AC works (and works great!).

I've recently moved to Georgia and so I need to fix this, please help!

My vehicle is a 98 Volvo S70 with 305000 miles on it.

So far what I've done:

I disconnected the middle plug on the cooling fan relay and grounded them both one at a time. Upon doing so the fan worked one being high speed and the other low (I can hear the difference in speed). So therefor I'm thinking relay is functioning.

Then I checked the plug for voltage with the AC on high. One socket tested about 10V the other about 6V. Not sure what is going on here I would expect one to be 0 volts since I doubt the car was that hot to require the high speed to be engaged.

What is weird to me is as soon as I reconnected the plug (with the AC still on) the relay makes a noise and I can see a slight spark from inside (it was dark outside) so some voltage has to be going through. But again if I jumper the relay to ground it works perfectly? Any ideas? Could the relay still be bad even though it works when I bypass the cars computer.

Please help!

 

Any ideas of what is causing the low speed fan to not work?