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Topic: A/C blows thru defrost vents (Read 1272 times) previous topic - next topic

A/C blows thru defrost vents

All of my A/C and heat settings blow thru the defrost vents, is there a door or something in the system that is stuck, how can I free it up?

Re: A/C blows thru defrost vents

Reply #1 –
You've likely got a vacuum problem. These cars use vacuum to change modes and a cable to change temperature. Check the vacuum tree on the firewall near the brake booster (under the hood) and the hose from it to the intake
2015 Mustang GT Premium - 5.0, 6-speed, Guard Green - too much awesome for one car

1988 5.0 Thunderbird :birdsmily: SOLD SEPT 11 2010: TC front clip/hood ♣ Body & paint completed Oct 2007 ♣ 3.55 TC rear end and front brakes ♣ TC interior ♣ CHE rear control arms (adjustable lowers) ♣ 2001 Bullitt springs ♣ Energy suspension poly busings ♣ Kenne Brown subframe connectors ♣ CWE engine mounts ♣ Thundercat sequential turn signals ♣ Explorer overhead console (temp/compass display) ♣ 2.25" off-road dual exhaust ♣ T-5 transmission swap completed Jan 2009 ♣

Re: A/C blows thru defrost vents

Reply #2 –
Also check the vac hose that goes inside the passanger side wheelwell to the vacuum canister which is mounted inside the inner fender. A few years back I had the same problem with my 87 3.8. Whenever I accelerated the HVAC would go from vent to defrost. I diagnosed it and found that the vac hose was disconnected from the vac canister. I loosened the inner fender well and pealed it back just enough so I could repair the hose and reconnect it to the canister. It also might be possible that the canister could be cracked.