1998 BMW 740 NO HOT AIR WHEN HEATER IS ON

  • Tiny
  • DBP
  • 1998 BMW 740

Heater problem
1998 BMW 740 V8 Two Wheel Drive Automatic 145000 miles

When I turn on the heater or defroster no warm air comes out of the vents. It just blows cool air. When using the A/C or just the vent on cool everything works fine. I just can't get it to blow warm air.

Sunday, May 31st, 2009 AT 11:20 AM

3 Answers

  • Tiny
  • Dr. Hagerty
  • Expert
  • 9,713 posts

It is very possible the heater valve has failed and will require replacement.

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Sunday, May 31st, 2009 AT 2:41 PM
  • Tiny
  • DBP
  • Member

Is this something that is located in the engine compartment or is it under the dash? Is there a way to test this valve before replacement?
Thanks.

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Monday, June 1st, 2009 AT 8:10 AM
  • Tiny
  • Dr. Hagerty
  • Expert
  • 9,713 posts

It is under the hood. It is on the fire wall, just follow the heater hoses. Testing is done by turning the heat on and feeling the hoses to the heater core, if they're cold the heater valve is suspect and at that mileage they have a high failure rate, go to Realoem. Com for the price and availability of your heater valve.

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Monday, June 1st, 2009 AT 8:32 AM

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