Does the T-stat control the fans?

[CindyLynn]

I have a 95 Monte Carlo 3100 and I do believe that the T-stat is getting stuck. Here's the story: it will overheat (slowly) while sitting idle (ex: Bank line, McDonald's). I know that the fans aren't kicking on AT ALL, the t-stat doesn't appear to be opening. We also checked the fuse box. So, the questions I have are: 1. does the t-stat control the cutting on of the fans for cooling? 2. How much should a t-stat job for this car run me?

Thanks again for your help!!

[richtazz]

The thermostat indirectly controls fan operation. The t-stat's job is to regulate coolant temp and flow by restricting/opening. If the t-stat is stuck wide open, the vehicle will not build proper coolant temperature, and gas mileage and driveability will suffer. It it sis stuck shut, the vehicle will rapidly overheat. If it is slugish to open and close, the engine temp will fluctuate greatly. When coolant temp reaches a certain level, there is a sensor mounted near the thermostat that sends the temp signal to the ECM and tells it to turn on the fans. There are two relays in the underhood relay center that control each fan. One is marked primary and one secondary (or auxillary). Check the relays first if you don't have a check engine light on (since a bad temp sensor should trip a CEL). Try turning the a/c on MAX to see if the fans operate then. The HVAC is set up to turn on the fans automatically, regardless of coolant temp sensor reading, when the A/C is turned to max. If the fans still don't come on, you may have a bad fan motor or two.

[richtazz]

As far as cost, the T-stat should be less than $10, but it's a bear to change. Labor will be about an hour.

[Henry_17]

I had the Tstat go on my '01SS this winter. the tep gauge wouldnt read anything, it stayed right at the bottom. The fans would turn on when I turnered on the car and wouldnt shut off for a few min after I shut the car off. The car wasnt hot enough for them to come on.
I changed the thermostat and unplugged the battery for an hour. When I talked to the dealer they said that I needed to tap the unplugged batter cables together than let it sit unconnected for about an hour.