1980 CADILLAC FLEETWOOD HEAT WILL NOT TURN OFF

  • Tiny
  • HHTS
  • 1980 Cadillac Fleetwood
  • 72,000 miles

Previous owner said heat will not turn off so he bypassed the heater core. I want heat for winter so I want this car back to original. What could be wrong with the car that the heat will not turn off? Could this be the climate control switch ora relay?
Does bypassing the heater core do damage?

Saturday, November 2nd, 2013 AT 7:57 AM

5 Answers

  • Tiny
  • hmac300
  • Expert
  • 42,950 posts

No bypassing the heater core doesnt' damage anything. Due to age of your vehicle we dont' have much info available. You have auto temp control so have a mechanic see if he can get the control head to see what is wrong with it. I thin you hit off an d defrost buttons at same time for it to diagnose itself to see what is wrong.

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Saturday, November 2nd, 2013 AT 8:05 AM
  • Tiny
  • HHTS
  • Member

It doesn't have a digital climate control. I uploaded a picture of what is there.

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Sunday, November 3rd, 2013 AT 2:45 PM
  • Tiny
  • hmac300
  • Expert
  • 42,950 posts

Ture but it's auto temp control these are a bear for someone inexperienced. The manual also doesn't cover heat won't shut off so i'm sending instructions on how to check for no eec meaning it doesn't light up also check all your vacuum lines for leaks as well as connections. Also check the water valve on engine to see if it closes with a/c on that could be the problem as well. It shold have vacuum an dit shold be colder thant the input line.

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Sunday, November 3rd, 2013 AT 3:39 PM
  • Tiny
  • HHTS
  • Member

I did some more checking and found that the blower motor does not turn off. What would cause that?

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Saturday, November 9th, 2013 AT 4:08 PM
  • Tiny
  • hmac300
  • Expert
  • 42,950 posts

This car is over 30 years old, I am taking a huge guess on this as I personally have not worked on one of these in ages. Either the programmer is bad or a component in it or the ground to it. Or the blower motor circuit board. Seepics

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Saturday, November 9th, 2013 AT 4:20 PM

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