My radiator fans are ON all the time. It started a few weeks ago, it is winter and cold and they turn on 1 minute after starting the car every morning. This is a 1994 Intrepid ES w/ 3.5L and 225/60-16 tires. I tested the Low and High speed Fan relays (LSFR and HSFR)and both are good. I replaced the Temperature Control Sensor (TCS). My Haynes manual says the Power Control Module (PCM) receives a signal from the TCS and turns on the LSFR and/or HSFR. I removed and cleaned all connectors to the LSFR, HSFR, TCS, and PCM. I cannot see anything "burned" on the PCM circuit board. Any ideas?

 

Hi, looking for help on this, too, it just started happening on my 94 3.3l. First thing in the morning, the fans come on shortly after starting the car, then they kick into high mode. They run constantly. They hardly ever ran before this. If they did, they'd cool the engine down and shut themselves off. The only thing I can tell you about mine is that the low relay (off hand I can't recall it's labeling) is energized. Pulling the relay will shut the fans off, but of course they turn back on as soon as I plug it back in. Does the temp sensor fail closed? Is there a way to test this? Is there a way to control this from the computer? The temp guage never rises above the "1/4" mark (I think there are 3 marks, and it goes to the first one, never past it). The only advantage I can see to this problem is that people in parking lots seem to hear me coming better than they used to!

 

I would not worry too much about the fans running all the time. I would be concerned if they never turn on, however. The way I see it, mine has been doing this on and off for the past year or so, it will just prolong the life of the head gasket in my opinion!

 

Find the fan relay in the PDC and switch it with a another relay. You may have a relay grounding when it shouldn't.

 

Still trying to track down this problem, I don't want the fans to fail from overuse. The relays are working properly, but I guess that doesn't mean something hasn't grounded in the circuit. Can the PCM be told by a diagnostic tool to turn the fans on all the time? If so, then the tool can tell them to shut off, too, right? It is annoying to hear the fans kick on as soon as the engine is started. If the fans were supposed to run all the time, they'd be connected directly to a belt like in the old days. They are noisy!

There are several others with this same question on this forum, yet nobody has come up with a decent answer on getting them to function properly. While I'm at it, anybody know of a good, yet inexpensive,diagnostic tool for a DIYer like me?

 

I think I may have stumbled on an answer while I was researching another problem for someone else. In the manual I found a small blurp about how the A/C pressure transducer "functions as the refrigerant system pressure sensor. It supports the condensor/radiator fans and compressor functions."

This may be the problem! It may bean A/C malfunction causing the fans to come on as the fans do have a dual purpose. Not only are they used to cool the engine, but they are also used to cool the condenserand the A/C may be sending the "turn on command", not the engine. Just an idea to try.

 

passenger side of rad at the bottom is the AC high pressure switch. Unplug it and see if the fans shut off. If so replace switch as it is bad. Simple test.

 

Yes, but don't forget it could be a shorted wire (to ground). If the connector is unplugged and the malfunction still exists, it still could be in this system and still requires futher troubleshooting.