Mr Goats

my main ac vents arrnt working but my defrosters are. what would the cause of this be? i drive a 96 mustang

BigDawg

you been doin any under dash work??? You might have had a vacumn line come loose, the whole HVAC system is run on vacumn. Or you might have did some work under the hood, and knocked a vacumn hose under there loose.

ODB

Slow leak possibly. go and buy a bottle with a gauge on it...they are about 25 bucks.check your pressure before you add....but sounds like you need it.

Zman

yes check all the lines, very common problem. on 87-93 they have a vacuum ball located under the fender on the pass side that goes bad. Looks like a big plastic softball. Not sure where its on a 96

CC801

that will not be caused by low system pressure.it is caused by a vacume leak though.

n8secstangg

its 100% a vacuum line problem...source vacuum to the head unit to be exact...start by checking the vacuum line that comes out of the cab into the engine compartment by the evaporator..trace it to the distribution block on the drivers fender well...if all is good there then you have a problem under the dash ...when the head unit doesnt have a source vacuum it goes into default mode and blows out the vents...

chad

stangkrew94

I have Had this problem!There Is a little line that Run's the back of the firewall!! I would check that one!! It Gose from the tree On the drive side!!! I Have broke that line twice when working on the car!!

Mach1OP

prezactly

Mr Goats

that was exactly the problem. little tiny hose caused big problems. i just bought some bulk hose from Advanced and i was god to go

stangkrew94

I Hate that little Hose!!! hahahahah I Think that was the first time I Have helped someone with there problem! I am always asking for help!