I have a 1998 Volvo S70 (non turbo) with about 112k. A few weeks ago when it was very cold the tempature gauge looked stuck at the bottom, when it finally kicked on, to under 1/2 way, the check engine light went on, and also the heat is not blowing cold when this is happening.. Shortly thereafter it was also hard to start. I took it to a mechanic who changed the coolant sensor and battery.. The next few days were warmer, and all was fine.. till it went to 9 degrees, and everything happened all over again! any ideas? Also in 20 degree farenheight weather the fan runs like it's 110 outside for about 10 minutes after I shut it off!

 

Did they replace the thermostat as well?

 

Okay, today after reading some other posts I ASKED for them to change the thermostat since it's a cheap part.. They did, and said it's hard to check and see if it was bad, they also cleaned all of the parts around the sensor.. so far it seems okay, hope it lasts..Thanks for your help!!

 

I have the exact same problem with my 98 S70. My mechanic ran a diagnostic and said the error code is an intermittent cooing fan relay fault. I also read on a blog that the cooling fan relay can build up static and malfunction. Inside the garage, while idling,the cooling fan kicks on and off according to spec - so it's not a t'stat problem (at least notinmy case).

I have ordered a replacement relay on ebay. In the meantime, i just disconnected the power to my relay - and the car started okay. The temperature is still below the 3 o'clock position, though. It's very cold in the NE this week - so I'm not afraid of over heating.