Hi,

I have a 2001 blazer and since I got it last August the temperature gauge has been acting erratic. It would shoot up to 260 out of nowhere and stay there for a few seconds and drop back down to a normal running temperature. In March, it finally got to the point where it would spike to 260 almost immediately after turning the car on and stay there. I never could tell after I turned off the car if it was in fact overheating or whether it was just normal heat from highway driving. The AC worked fine at this point but the heat did not get hot. I changed the thermostat and I thought the problem was solved. Mid April brought back the same old symptoms. It is a little warm after I turn it off and this time the AC does lose coolness and the heat does not get hot. I live in Florida and this week is really the beginning of the annual heat so I do not need heat in the car but the AC problem is going to get me down fast. Thanks in advance for any insight.

Richard

 

I wonder if your ECT sensor is bad. It is located in the driver side cylinder head between cylinders 3 & 5.

You may also have air pockets in the system.

 

Air pockets was my first guess based upon the numerous previous posts I have read over the past few days and the lag time between replacing the thermostat and the relapse of the problem. What is the best way to get rid of air pockets?

Is there a way to check the whether ECT sensor is working properly?

 

The best way to get rid of the air pockets is to pull a vacuum on the system, but most get by with just elevating the front of the truck as high as reasonably possible with the passenger side a little higher than the driver side.

As far as checking the ECT sensor, I have posted the resistance chart in a few other threads. Try searching for "temperature+resistance" and have a look through some of those posts.

 

Thanks,

I will try that and keep you posted. Thanks for the help so far.