Heater control valve solenoid

Tiny
DCPLACE2007
  • MEMBER
  • 1999 GMC SUBURBAN
  • 145,000 MILES
Hi, my rear heater was not working properly so I felt the hoses to the heater core and one was hot, the other warm. I realized that the heater control valve was not getting vacuum at all. I followed the vacuum line up to the heater control solenoid and obviously it is not working. The vacuum line on the top of the solenoid is drawing vacuum. The htv vacuum line is not. I checked the two wire electrical connection to this solenoid and checked it with a test light and it shows nothing. One of the wires to this solenoid should be hot, right? I don't want to replace the solenoid if it is not faulty. I am not sure exactly what do do at this point. I believe the hcv is not faulty, as it is a simple device which works off vacuum. My concern is the device on the firewall that the vacuum lines connect to--the electrical connection to it. Thank you. Dave.
Friday, October 14th, 2011 AT 3:48 PM

4 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Most solwnoids start with 12 volts and the controller, whatever it is, will control the ground. Check all your fuses to start.

Can you manually open the valve to see if the heat works? Thi will verify that the heater core is not clogged.

I will track down a diagram for you for the system and upload it to you.

Roy
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Friday, October 14th, 2011 AT 4:02 PM
Tiny
DCPLACE2007
  • MEMBER
  • 28 POSTS
I definitely moved the valve on the hcv and it circulated the heat to the rear heater core. If it were as simple as replacing the heater valve solenoid, that would be great, but the electrical may be the issue. Now, the hcv stays in the closed position until the solenoid allows vacuum to the hcv, correct? I checked the fused for the rear heater, and it is good. Not sure if there is a seperate fuse for that solenoid, is there? I really appreciate this as it will keep my windows from fogging and keep my two children warm in the back. I have to boast that I replaced the entire steering system on this suburban myself. It was a task with plenty of curse words said, but I got it done. Firestone asked who did the steering system and I told them me. They said it was rock solid and done very well.I never knew it would be so difficult to remove and install ball joints. Thank you very much for the help you are giving me.
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Friday, October 14th, 2011 AT 4:31 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Look at all the fuses. I believe there is 2 panels. Check them all with a test light.

Like I said, I will forward a diagram soon.

Roy
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Friday, October 14th, 2011 AT 4:41 PM
Tiny
DCPLACE2007
  • MEMBER
  • 28 POSTS
Hi, I was wondering if you possibly found the wiring diagram for this solenoid. All the fuses checked out good. Thanks. Dave.
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Sunday, October 16th, 2011 AT 7:19 PM

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