1999 2.7 loud squeak

Hi everyone,
I have had a loud squeak that started a few months back with the defrost on and only on a cold start. Well this squeak has since progressed to where it had a loud squeak all the time with the defrost on. Any ideas as to what this could be? I have read about blower motor issues but that doesn't seem to be the case.

Thx!

 

Does it sound like belt slippage?. If you select defrost and turn the interior heater/defrost fan on it cycles the A/C compressor.

 

Yes kind of sounds like belt slippage but not positive of that. It only does it on the defrost settings. It won't make the noise on when on the vents or strictly floor. Ac button on/off doesn't make a difference.

 

Open the hood,, select whatever you are selecting on the dash , cold start it, then jump out listen. You should be able tell if it is belt slippage pretty easy.

 

Ok I will check that out after work. Are there multiple belts on the 2.7 or just one?

 

Multiple belts. A helper would be handy. Someone to flip on the fan switch once you stand in front. Select DEF full heat, startup, have helper click the defrost/heat fan switch once you are in position with flashlight on the A/C compressor belt. You'll hear the chirp and steady squeak. (You might even see the belt squirm and try to wrap a tiny bit,,sorry,,that's something for another day, I digress.) Not really needed but if all of this is entirely new to you,,it never hurts to have a witness or a second helper.

 

When using defrost, I believe the HVAC system uses the AC compressor by default to help remove moisture out of the cab. I'll bet it's the ac belt that needs to be replaced or snugged up.

 

The defrost duct inside the dash takes years of hot/cold cycles. If you get a tiny split in that,,it can sound the very same, and then goes away when the fan no longer moves air. That split can heat up, expand and change tune once again. That is what is called a vicious circle to no end. Can be easier to nail down sometimes. Very rare, but a distinct possibility. You can also get trash caught in the ducting close to the fan and on the tiny blades of the fan creating a New Years Eve party whistle.

Belts first I think. Easy stuff first.

 

Do you either of you have a diagram of the belts' cycles or which one the ac belt would be?

 

Wow, that duct deal is new to me. Glad you put that out there, for future reference.