2000 Monte SS, a few problems...

During the summer I noticed that my temp gauge wasnt working. Did a little reading and found out that I needed to change my Engine coolant temp sensor. Between the time I read that and changed it, I also noticed my AC wasnt working, the radiator fans turned on and stayed on as soon as I started the car and my check engine light came on. So I changed the sensor, had Autozone clear the check engine code and all sytems worked as normal. Happened again here about a month ago. Changed the sensor, had the code cleared and again, everything worked fine. But a week later, the fans are on, no temp gauge, no ac, but, the check engine HAS NOT come on. I don't think it is the temp sensor again, but I have no idea what it could be. I have a Haynes manual for the car and it said to take an ohm meter and check the plug that connects to the temp sensor, with the key on, and make sure you are getting at least 5 volts. I am getting the 5 volts, so what can cause this to happen? ANY help would be great as it takes forever for the car to warm up with those dang fans on constantly, and with it being winter it only multiplies it.

I know the easy thing to do is take it to a chevy dealer and have them hook it up to the computer and they can fix it, but I am not made of money and would raher avoid that if I can.

Again, any help would be great!

Is it possible that the act of unplugging and plugging the connector on the sensor was the real fix. What you need is a scan tool to see what data the sensor is giving. Once you can see this you can then do a wiggle test to see if it flakes out. If it does than it could be as simple as a pigtail (connector). The other thought is to make sure the coolant is full. If that sensor ends up in a pocket of air it will not read correctly!!

Thanks Airjer for the info. Do you think it could be as simple as the thermostat? I did a little more digging and found that some other people experinced this problem and the thermostat was bad. Figure I would try that as it is only 8 bucks for the stat. If that doesnt work, then I will try and replace the pig tail as you suggested.

If it was the t-stat the fans would not come on and there would be a code for insufficient coolant temp for closed loop operation.

Well, I went ahead and changed the t-stat, figured if anything, might be good to do since I have over 100,000 miles on it. Changed and the same things were going on. I took the plug off the engine coolant temp sensor, blew it out with some air, plugged it back in and still had the same things. So, as I read in another thread on here, I disconnected the negative battery cable for about 5 minutes, plugged it back in and EVERYTHING is working normal.

I guess the real test will be if it keeps working or starts it again in a few weeks.

Airjer, you mentioned a scan tool to see what code it is throwing. Wouldn't the check engine light need to be on to get a reading? In my first post, the check engine light used to come on, but this time the check engine light has not come on. So not sure what I could have done to get a code. Any recommendations as to what might be causing the problems now? I am lost as to what it is.

Airjer, you mentioned a scan tool to see what code it is throwing.

No, I said "What you need is a scan tool to see what data the sensor is giving.", which is much different than looking at trouble codes. A good scan tool will give you a wealth of physical sensor data that can be interpreted to find a problem.

No, I said "What you need is a scan tool to see what data the sensor is giving.", which is much different than looking at trouble codes. A good scan tool will give you a wealth of physical sensor data that can be interpreted to find a problem.

Hmm, ok, I never heard of those. Thanks!

I think you might have code reader and scan tool confused. A code reader will do just that read codes. A scan tool depending on how much you choose to spend can read codes, data, and allow you to control some vehicle functions with the tool among other things. Far more versatile and sophisticated than just a code reader.