I have a 2002 Grand Caravan Sport. A couple of weeks ago, whenever I turned the power on for the climate control, I would get a very loud oscillating sound from the engine that would speed up when I stepped on the gas. Shutting off the power to the climate control doesn't make it stop. The only way to make it stop is to shut off the engine and start it again. It's definately not the alternator as I have had it checked. It's hard to tell where the sound is coming from as it is so loud and the vibrations makes everything hum...even the gas pedal. It seems to be coming from the top of the engine near the air intake as that is where the sound and vibrations are the strongest. When I checked, there were no trouble codes.

Any suggestions or ideas. We are expecting snow tomorrow so heat would be a bonus if not a necessity.

 

I think that is your cooling fan. Open the hood, crank it, turn on AC. Then shut the AC off. The cooling fan will sometimes stay running after the AC is shut off. It has to come on when the AC comes on to draw air into it. Your fan may going South on you. Its really hard to tell where sounds are coming from under the hood. My AC compressor in ,my 2004 Caravan, 2.4 liter is very noisy. It sounds horrible. You get a screwdirver and place it various componets and put your ear up to it. Only a long screwdriver though.

 

I'm pretty sure it's not the cooling fan as I tried much the same thing you had suggested but used a wood hockey stick. As I alluded to, it seems to be near the top of the engine just after the air filter. Just now, I've started to get a clipping sound from the same area that speeds up and slows down with the engine.

 

There is a TSB 24-004-04 for a/c failure. TSB is good for 2001 to 2003 T/C and Caravan's, TSB will only cover the van under 7 years or 70k miles.

 

It seems the sound is the starter motor not disengaging from the engine or will all of a sudden, while driving, engage.

My thought is that it might be one of 3 things:

- starter solenoid
- starter relay
- Powertrain Control Module (perhaps a bad ground)

Any thoughts or suggestions.