Why does my 97 the AC switches to heater on it's on? on 1997 Ford Explorer

When I turn my air conditioner on it runs for a little bit then there's a sound like a vent is closing on the inside then it blows hot air.

by in Potwin, KS on July 25, 2013
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3 answers
ANSWER by , July 26, 2013
AGREE WITH PUSHROD OR ITS A BLEND DOOR ISSUE IF EQUIP
ANSWER by , July 25, 2013
probably the heater wire is making contact and causing the heater to come on.
ANSWER by , July 25, 2013
There is a heater control valve under the hood, IF this valve is not stopping the flow of HOT coolant from entering the hvac unit, that will cause this problem! Located in the heater hose near firewall.