synergy58

My air flow only works at the main vents and defrost, not the floor. occasionally the AC makes a horrendous noise for about 30 seconds, then it quiets down like it never happened. The noise is like a sucking squealing sound. The AC blows cold, but the compressor cycles a lot. Not sure what's happening here. Any ideas?

Cheddarnut

Well, there is a bearing in the AC compressor. That would make a racket if it was failing.

Turbo X_J

Is this question about a vehicle, if so what kind, do you know what year the vehicle was manufactured?

synergy58

2001 Cherokee.




The sound is hard to describe. Something along the lines of a howling, NOT a grinding or belt squealing noise.

As for the air flow, It has been suggested that it could be a vacuum leak causing the air not to flow to the floor, but I can't figure out where or how this would take place. Is there an electrical apparatus that controls the movement of the vents?

CCKen

The HVAC door actuators are vacuum controlled.


Here's an image that describes the actuators on the left side of the HVAC unit:





Here's the back of the climate control panel where you can see all the vacuum tubes (middle) that go to the various door actuators:





.
Photo of the actuators:

CCKen

If the compressor cycles a lot you may be low on refrigerant charge. You may want to take it to a HVAC shop and have the charge checked.

TomSchaeffer

I had a similar problem with my car, the air would not flow on the floor on any setup. If I remember right I had to change the vacuum switch of the AC

Fred/N0AZZ

Post this in User CP so people will know without asking what yr you have. Makes it much easier to help you with the correct yr showing it every post you make.

cruiser54

I stole this from CCKen one time:

synergy58

Holy cow! These pics are awesome!!!!

Thanks so much!

synergy58

Great diagram!

Thank you!

So, I guess I'll have to trace everything from start to finish to determine what's going on here. Ok. Well, time to get dirty again

synergy58

So, after replacing the serpentine belt, I have determined that it is my AC compressor that's making this infamously loud noise. The compressor pulley still turns, it still blows cold air, but it cycles about every 5-10 seconds (low on freon). When I turn the ac switch on, the squealing noise starts, off, it stops.

Does this mean my compressor is shot? or can it be because its low on freon?

Like I said, it still works, blows cold air, but makes a loud squealing noise when i turn the ac switch on.

If it is the compressor that needs to be replaced, does everything need to be replaced along with it, like the hoses, and...?

Thanks!

ss427ci

Glad I ran across this thread, a lot of good info in here that should help me out. Thanks guys!