Ac only blows defrost - Ford F150 Forum

82f100 · 07-14-2012, 12:05 AM

My ac only blows out of the defrost vent. Got a fix?

Mamushka · 07-14-2012, 12:50 AM

Quote:

Originally Posted by 82f100

My ac only blows out of the defrost vent. Got a fix?

Typical issue is a vacuum leak. The actuators that control where the air is directed (floor, panel or defrost) are "powered" by vacuum. It is common for the default (no vacuum) configuration to be the defrost setting.

You should have a vacuum line going into the firewall from the engine compartment. I would check that first.

superduty · 07-14-2012, 12:55 PM

Look up my thread engine fire. Im on my phone so I can't post a link but there's a vacuum line that comes out of the fire wall on the passenger side. I think a white and a black. The black is the selector iirc.

Jeckel · 09-06-2012, 05:16 PM

Just to bump this thread, my 95 has a similar issue. below 40 mph the ac blows through the vents, over 40 you can hear the door close and it blows thru the defrost. Could it also be the same vacuum problem?

Mamushka · 09-06-2012, 09:45 PM

Quote:

Originally Posted by Jeckel

Just to bump this thread, my 95 has a similar issue. below 40 mph the ac blows through the vents, over 40 you can hear the door close and it blows thru the defrost. Could it also be the same vacuum problem?

More than likely. I would guess if you accelerate hard to 70 or are climbing a hill (low manifold vacuum) you will be on defrost. If you let off the throttle at speed your AC will probably come back.

USAF93 · 09-09-2012, 08:36 PM

I just had this same problem. You can view my photos here http://www.f150forum.com/members/usa...c-vacuum-line/