Hi everyone, im new to this forum but a long time dodge owner and DIYer so im looking for some help that I cant seem to find the answer to on the good old fashioned internet.

here is my issue:

Idel fluctuates from 1000-3500 rpms only when I engage the fan and start to blow air. doesn't matter if the AC is on or not. No CEL.

what ive tried:

1. replaced the IAC a couple times and this doesn't seem to help
2. throttle body has been cleaned a couple times- no difference
3. tested for vacuum leaks and there arent any that im aware of.
4. replaced the breather pipe and hose as there was a small crack- no difference
5. sprayed WD-40 around a bunch of hoses to see if I could detect any sort of vacuum leak- couldnt find any.
6. replaced blower motor

my thoughts of what to try next-

-MAP replace
-Throttle position sensor replace

not sure if this will help or not as it seems the issue is tied to the motor kicking on and blowing air which throws off the idle. thanks to anyone that can point me in the right direction here!

 

What year is your truck?

 

2002. 1500 SLT. 118K on it.

 

Which engine?

With that big of a fluctuation, I would suspect a serious vacuum leak somewhere.

 

4.7L engine. I would have thought a vacuum leak as well, but testing all the hoses came up with nothing. It baffles me as its when the kick on the vent that it starts up.

 

Kick on the vent? A/C? Heater? Both? Neither?

 

Both. doesn't matter if its the heater, AC or just Vent blowing air.

 

Well that's just bizarre...... Bad ground somewhere??