2003 FORD F150 HEATER ONLY BLOWS ON DEFROST

  • Tiny
  • F150fxrguy
  • 2003 Ford F-150

Heater problem
2003 Ford F150 V8 Four Wheel Drive Automatic 230000 miles

Electronic climate control unit. Heater is currently only blowing on defrost. A/C works good on vents, floor and defrost. Heater will NOT blow on floor. I replaced the heater unit once and it worked ok for about 6 months, but then defaulted to the same defroster setting only. Is this a vacuum leak or did the ECU fail again? I now have 2 suspect failed heater units. Are these repairable? If it's a vacuum leak, where should I start looking?

Sunday, June 20th, 2010 AT 11:58 PM

1 Answer

  • Tiny
  • Jacobandnickolas
  • Expert
  • 68,287 posts

I would start with the idea of a vacuum leak. Start by checking under the dash and the hood. That would be my first guess.

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Monday, June 21st, 2010 AT 12:12 AM

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