AC Help

[ericwiersum]

I have a 98 V6 mustang and having some AC issues. The AC only blows out of the deforst in every position on the dash. Max AC, Norm AC, vent, mix...all come out of the defrost. want to fix it myself if anyone knows how? Live in TX so its hot here.

[Davescort97]

The blend door which is operated by a vacuum motor is hanging up in defrost mode by default. Whenever the heater/AC controls are broken the system reverts to defrost for safety reasons. I suspect the vacuum line going to the controls has come loose or the door is hung up for some reason. It's doing what it's supposed to do when the system malfunctions.

[ericwiersum]

ok is that something i can check under the hood or inside by the dash? and where would i check this?

[Davescort97]

You can check it under the hood on the intake plenum (manifold). Listen for a whistling sound and visually check that all vacuum hoses are on the ports and not cracked or deteriorated. To check under the dash will be difficult. You'd have to take the Heater-A/C box out. Most likely, the culprit is the vacuum connection under the hood. There is little chance that the hose would come loose under the dash. Usually, the hose under the hood is knocked loose and not reconnected after engine work has been done.