Fan stuck in a loop, goes on for ~10 seconds, off for 10, repeat

[elvisjer]

Hey all. WHen my PT is at idle, it feels like it is stuck in some type of loop. The cooling fan will turn on for 5-10 seconds and then turn off, then it repeats with no signs of stopping. No codes present. The engine after warm always rolls around mid point on the dash temp sensor between hot and cold, not dependent on the weather. Has anyone had and/or solved this problem? Im worried it may be a sign that some other component is out and could cause potential damage.

[CREWZIN]

I did a search and can't find anyone else with your problem.

There are many components that come into play to turn the fan on and off. Relay (both high and low) PCM, ECT (Engine Coolant Temperature) sensor and maybe more.

My guess would be one of the relays. If it's the high speed fan then you can switch the relay from the horn to the place where the high speed relay is because they are both the same kind of relay. If it's the low speed, that relay if different from any other relay in the fuse box.

Is the compressor also going on and off at the same time as the fan? If it is, that's a sign of low pressure in the air-conditioning system and the problem might be the high pressure switch (I had that go bad) or low R-134 in the system itself.

[quicksilverdon]

My guess is that you have defrost set - which turns on the A/C, and the A/C turns on the fan - - BUT your A/C is low on freon (or whatever) and it cycles off and on...