ac/defrost noise

[Mr Mike]

all right, being a mechanic I know how hard it is to diagnose things you cant see or hear... but...

Driving along, any RPM andy speed. If I switch to defrost or use the AC I get a "pssstt" noise. Like my BOV only not as loud. as the AC pump enguages this happens as well. I know its not belts, they are tight and right. is it possible that the BOV is popping off when ever the ac pump enguages? seems odd to me...

any suggestions? or questions to help narrow this down

Mike

 

[redlinerally]

It happens on my '06 2.5i... no BOV for me.

I think it's a pressure valve or something. But mine is functioning fine, and still makes that noise.

 

[Mr Mike]

well that's good to know, i'm not so worried now. Thanks for the reply

Mike

 

[redlinerally]

No prob.

Basically, when you turn on the defrost, it automatically turns on the AC so your windshield doesn't fog. I'd love to dis-engage that for the winter tho, since there's no need for that...

My wife had pointed out the 'hiss' that you mentioned to me. I was told by the dealership that it's normal, and just an AC sound.

 

[Rightseat]

pretty sure the pssst sound is a vacuum-actuated valve opening/closing in the AC/heater assembly. the AC makes the defroster work MUCH better, esp in winter when the cold dry air won't hold as much moisture.

either that, or you got a squirrel nest in there.

DG

 

[Mr Mike]

No squirl nest I dont think. I might have a vac leak then because its really loud, not one of those shhhh did you hear that noises but a WTF was that noise kind of noise ha ha

 

[Pedro]

try on a rainy day or a wet snowy day using the defrost with the heat on all the way. I drove home from Burlington, VT last winter and the only way I could keep the windsheild clear was with the AC on. THe side windows were fogging too, it was nasty.