How would I know, by looking at the temperature gauge, that my thermostat is stuck open?

If it was stuck closed, I would overheat, but how about stuck open?

 

Pretty sure you temp gauge would stay low and your heater would not throw very warm air.

 

+1 to JimKW. That is EXACTLY what happened to my wife's XC-70 when the thermostat stuck open. Granted.... different car but same principal.

Glenn

 

Tech just informed me that a stuck open thermostat will cause your vehicle to overheat at highway speeds because the coolant travels through the rad too fast and doesn't get cooled enough. Your temp gauge will go up very slowly... It's really easy to pull the thermo, on top of the engine on the passenger side, right in the middle... Make sure you have a star tool! Make sure you get it changed, because I read that another 850 driver blew his heater core from the thermo being bad.

 

^During city driving, the t-stat will look normal, but on the highway, you will be very very cold.

 

yeah, that was mine that blew my heater core haha

get it changed asap it's a 5 dollar part and takes about 2 min to change


good luck

 

I noticed that my temp gauge goes kinda slowly when I just started up the car and use the A/C right away, on a hot day. I think this is normal because the fan is always on with the A/C, correct?

Sounds like my t-stat is fine ...

 

If the t-stat is stuck open, it is bad. Just pick up a new one from fpc grotten for $5.

My 850 would hit normal operating temps within 5 miniutes when the outside temp was in the single didgets with wind chills in the negatives.

Nick