I just put a new cooling sensor in my vette. The one that turns the fans on at 176 and off at 166 to keep it cooler. But the problem is it doesnt turn them on at all, and the Temperture gauge reads well over 260 even if the car has been sitting for a long time. What is the problem :confused:

 

Could be a bad switch, stranger things have happened. I bought a so called low temperature fan switch for my car and it made no difference at all what temp. the fans came on so I returned it for a full refund. Also make sure you did not damage the connector or wiring during the install. Good luck.

 

I don't know for sure about the '90 Vette (which your profile says you own) but on my '86 there are 2 coolant temp senders. One is screwed into the front of the manifold, a couple inches to the right of the thermostat housing (where the upper radiator hose attaches to the engine). This sender has a 2 wire connector and sends it's signal to the ecm to tell the computer what temp the engine is at. There is another sender screwed into the right cylinder head between spark plugs number 6 and 8. This is a 1 wire sender that tells the dash temp guage how hot the engine is. If you dash guage is showing max temp even when you know the engine is cool I would suspect that this sender has the wire shorted to ground somewhere. Pull the wire off and see if the guage goes to max cool (the lowest temp reading it will show). Another thing to do would be to plug a scan tool in and watch the live data and see what temp the ecm sees from it's sender.

I'm not sure if you are talking about a switch that turns on the booster fan in front of the radiator. I can't remember where that switch was on mine since I got rid of mine to make room for my oil and tranny coolers. Seems to me that switch may have been on the left cylinder head up near the front.

If you have replaced the sender for the dash guage and it still reads high you may have a bad ground connection somewhere to the dash cluster which would/could cause this.

You can check your main cooling fan by shorting out two terminals in the aldl connector under the dash and turning the key to the run position without starting the car. I have one of those cheap plug in code readers that does this. I can't remember what two terminals to short out but I'm sure somebody else can post that.

Good luck.