Heater Problems

FORD MUSTANG
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91MUSTANG
  • MEMBER
  • 1 POST
I have a 91 Mustang LX 4 cyl w/180,000 miles. When I step on the throttle, my heater will switch from blowing through passenger Vent to Windshield Defrost. I've backflushed my heater core, didn't do much, but has helped with heater efficiency. Any suggestions? Perhaps bad wiring? Or bad heater core or even blower?
Feb 18, 2007 at 7:49 AM
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MIKE H R
  • MEMBER
  • 3,094 POSTS
sounds like it has to do with the heat selector, check the connections. you say that when you step on the throttle it does it. check around the gas pedal see if there is a rubbing wire that has to do with your heating selector..
Feb 18, 2007 at 11:58 AM
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TAURUSWHEEL
  • ✓Experienced Mechanic
  • 718 POSTS
I believe these systems are combo of electric and vacuum, switching to defrost mode from any other position is, I'm betting, a classic case of vacuum leakage or vacuum storage.. however always a chance of other cause, after all it's a car...
Feb 18, 2007 at 2:44 PM
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HUBCAP2
  • MEMBER
  • 2 POSTS
my 92 was doing the same thing and it was the vacuum leak check them good mine was very very small leak i over looked it 3 times
Feb 25, 2007 at 11:22 AM
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