It is overheating and has no heat?

Tiny
JACKANDBUDLIGHT
  • MEMBER
  • CADILLAC DEVILLE
I have a 1989 Cadillac coupe deville, 4.5 V8 it has 103,316 miles on it. It is over heating and has no heat. I replaced the radiator, thermostate, hoses, no water or antifreeze on the oil stick. I also replaced the radiator cap and pressure tested the system, it held good at 16 pounds.?
Tuesday, January 23rd, 2007 AT 7:23 PM

1 Reply

Tiny
SQM
  • MECHANIC
  • 6,383 POSTS
Hello,

The heater not working is likely due to an issue with the heater control valve.
The control valve is located next to the blower motor under the hood (see diagram).
It is a vacuum controlled actuator. Inspect that valve. Make sure that the vacuum hose is connected and the hose has suction.
The valve can also fail in the inside and be stuck shut. This will not allow coolant to flow and you will have a non working heater.

https://www.2carpros.com/articles/car-heater-not-working

As for the overheating issue, check the radiator cooling fans. Make sure they are operational.

Please let me know of any questions.
Thank you.
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Thursday, September 16th, 2021 AT 10:56 AM

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