Radiator Fans and A/C Don't Work



2001 Pontiac Aztek (The Edsel of the New Millennium). Radiator Fans (electric) do not turn on. Also Radiator Fans do not turn on when the A/C is turned one. In addition the A/C Compressor Clutch does not engage when A/C is turned on.

Used separate Power Supply to confirm that the Radiator Fans do work. All Fuses are good.

Question to anyone that has an idea. Are the problems of the Radiator Fans and the A/C related. Am I looking at a bad Computer. Would like some ideas before I break down and take it to the Dealler.


Some AC/cooling fan circuits are hot all the time. So there may be a fusible link that supplies power to these circuits that has burned.

The only way to find out is to aquire an accurate wiring diagram for these circuits for your vehicle.



I doubt that there is a problem with the computer causing this. I would suspect a bad relay or broken wire is causing the problem. You could try locating the relay for the fans and try tapping on it to see if that will make it work.

You should invest in a good service manual since it can save you money and time. Anyone using a seperate power supply to test with needs a manual also.

I liked you comment about the Aztec BTW. What were the engineers thinking?


Thanks for the input. So far everyone has suggested getting a wiring diagram. So thats my next step.

Appreciate it.


As far as your A/C, I saw a bulletin on your vehicle. AC compressor inoperative, this was for mitsubishi compressor only. It said to replace the AC high pressure valve. You might just be low on refrigerent.

Fuse 34 and fuse 40 for the fan relays, should be hot all the time. You can remove the fuses, one terminal for each fuse should be hot. I can describe the circuits for the fan relays, but, I’m not sure how deep into this, you want to get?


I just wanted to add, as far as the high pressure valve. The system would have to be pressured-up and running in order to check the valve for leaks. I guess it caused them enough problems, they finally put out a bulletin on it.

The computor grounds the coil side of the fan relays in order to energize them. It maybe the computor isn’t grounding them for some reason. The first thing I might check is the cts if the computor isn’t grounding the circuit.


How about the relays themselves? Have you checked them? Check the relays first. If they’re good, check for voltage at both the power circuit of the relays and the control circuits. If the control circuits are not powered, then the computer isn’t giving the fans the ON instruction, or there’s a break between the computer and the relay center. If the power circuit is nil, then it could be that fusible link Tester suggested.



To All

It took a while but I finally got a Service Manual. Located all of the key components and everything checks out OK. Did make one observation. When the 2 wire connector is removed from the Engine Coolant Temperature Sensor both Radiator Fans will turn on at High Speed. Has anyone seen a Temperature Sensor function in a way that properly signals the Temperature Gauge on the Dash to work properly but will not signal the Fans to turn on via the Powertrain Control Module?


After reading your original posting again I think that when you find out what why the AC clutch is not turning on you will solve the fan problem also. As a guess, this sounds like it may be a relay problem.


Bought this car in 2001. Ever since then no matter what the weather how hot or how cold the temperature gauge ALWAYS went up half way and stayed there. However earlier this year the temperature gauge went higher than half way. Thus I thought the cooling fans were not working. I broke down and finally took it to the dealer. After an hour they came back to me and stated that nothing was wrong. The cooling fans come on at the prescribed temperatures. They pointed out where the temperature gauge should be indicating when the cooling fans should come one. It was above the half way point. Just about 3/4. I then asked them why my temp gauge never went above half way for 6 years. They had no answer.

Thank you all for your input. I’ve learned more about how my vehicle is wired than I ever thought.


If this car has manual AC where you have to push an AC button to get things cooled down, then that button also overrides the fan circuitry and pretty much always turns on the fans. I’d look at the button and its wiring. Maybe the button or switch is not making contact properly, or the wires to it have come loose.