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I am having trouble with the heater in my 1990 CC. It blows air, but it's cold air. Here's what I've done so far:
1. Checked coolant level, and it's normal.
2. Cranked heater on full blast and felt intake and output hoses on heater core, and both are hot, indicating clear flow.
3. Checked vacuum line to heater control valve, and it's securely connected.
4. Removed instrument panel and inspected the heater control. The cable is securely connected to the temperature lever at the heater control end, and securely connected at the flaps on the other end behind the glove compartment.
Anyhow, I've come to a dead end and I have no idea what to do next. Any ideas?
Also, I'm having a hell of a time with my instrument panel. Every time I remove it, little chunks of plastic break off. The plastic is really brittle and it always breaks before the metal clips pop out. It's getting to where the instrument panel sags and there's hardly anything holding it up. Does anyone else have trouble with this? It's really frustrating and the brittle plastic makes me not want to mess with anything.
My suggestion is to saw the head off of the heater control valve, and connect the rubber hose right to the remaining stump. You should always have heat then.
Then at the end of spring, you could replace the valve so it doesn't interfere with your AC.
Also, YES those blue plastic dash cages are steaming piles of doo doo.
I have sold 3 dashboards to people who broke theirs, or have had them broken permanently by some idiot stealing a stereo just this year alone.
This is the classic broken heater blend door. Assuming you have the manual HVAC and not the Tempmatic, the heater blend door is cable operated from the control head. It is very common for the plastic bellcrank that operates the door to break, resulting in only cold air. Remove the glove box insert and you can see the bellcrank on the firewall, above the HVAC box. Operate the cable while watching the bellcrank and it will become obvious as to the problem. This was so common a failure that Four Seasons used to sell a replacement bellcrank. Unfortunately, the part appears to have been discontinued - I tried to buy one earlier this year and it was no longer available.
Depending on where it's broken, it can be easy to repair. On my 86 Caprice wagon, the pin that the cable fit over had snapped off of the bellcrank. In that case it was very easy to simply drill a hole where the pin used to be and use a small machine screw and nut to replace the pin. That fix has worked fine for several years. If the bellcrank arm itself is broken, you'll need to glue it back together, adding some sort of reinforcing plate made from metal.
Also, YES those blue plastic dash cages are steaming piles of doo doo.
I have sold 3 dashboards to people who broke theirs, or have had them broken permanently by some idiot stealing a stereo just this year alone.
Okay, well at least it's not me. You wouldn't happen to have another one on your hands, would you?
Originally Posted by MDchanic
How is your temperature door controlled? Vacuum or Bowden cable?
My money's on a bad cable or cable connection to the temperature door.
- Eric
The temperature door is controlled by cable. I was told that was most likely the culprit, but I've inspected it at both ends while sliding the temperature switch from cold to hot and it is securely fastened at both ends.
Originally Posted by rocketraider
Is it manual control A/C or Tempmatic?
This sounds like something a Tempmatic would do if something on its programmer failed. Vacuum checking relay failures are very common on Tempmatic.
It's a manual control, so I don't know. I've also been told it could be a thermostat....
This is the classic broken heater blend door. Assuming you have the manual HVAC and not the Tempmatic, the heater blend door is cable operated from the control head. It is very common for the plastic bellcrank that operates the door to break, resulting in only cold air. Remove the glove box insert and you can see the bellcrank on the firewall, above the HVAC box. Operate the cable while watching the bellcrank and it will become obvious as to the problem. This was so common a failure that Four Seasons used to sell a replacement bellcrank. Unfortunately, the part appears to have been discontinued - I tried to buy one earlier this year and it was no longer available.
Depending on where it's broken, it can be easy to repair. On my 86 Caprice wagon, the pin that the cable fit over had snapped off of the bellcrank. In that case it was very easy to simply drill a hole where the pin used to be and use a small machine screw and nut to replace the pin. That fix has worked fine for several years. If the bellcrank arm itself is broken, you'll need to glue it back together, adding some sort of reinforcing plate made from metal.
I've been told this might be the case, but I'm not sure exactly what I'm looking for. I have very little experience with car mechanics and this is the first thing I've tried to fix on my own. I removed the glove box and looked around. While flipping the temperature switch from hot to cold, I could see a metal arm moving back and forth behind the glove box. What exactly should I be looking for? And please excuse my ignorance; I have a lot to learn.
I've been told this might be the case, but I'm not sure exactly what I'm looking for. I have very little experience with car mechanics and this is the first thing I've tried to fix on my own. I removed the glove box and looked around. While flipping the temperature switch from hot to cold, I could see a metal arm moving back and forth behind the glove box. What exactly should I be looking for? And please excuse my ignorance; I have a lot to learn.
No problem, this is how you learn. The bellcrank arm that you see moving back and forth converts the motion from the cable to motion that moves the heater blend door open and closed. Look closely at the bellcrank. The left side arm connects to the cable from the heater control head. The right side arm should connect to a short metal rod that moves the blend door. If the bellcrank itself is moving with the cable, then verify that the metal rod is also connected at both ends and moving accordingly.
In the second picture: the round thing with the vac hose to it and #45116 molded in it is the vacuum checking relay. I would be greatly surprised if that thing is not the culprit.
I've been experiencing similar heating issues as Griswold '90 in my 1990 Custom Cruiser. I'm in the process of pulling the vacuum relay and just want to ensure that I don't mess anything up. I removed the glove box and the vacuum port and lock stud from the relay ( see the attached photo). What is the correct/best method of removing the vacuum relay so that I can install the new one? Thanks!
Easiest way is to remove the whole programmer assembly from the HVAC case. I think there are FOUR screws holding it to the case, then the aspirator tube and bellcrank lever need to come off. Pull the programmer out and you can then easily get to the individual components. The vacuum relay snaps into the programmer.
Easiest way is to remove the whole programmer assembly from the HVAC case. I think there are FOUR screws holding it to the case, then the aspirator tube and bellcrank lever need to come off. Pull the programmer out and you can then easily get to the individual components. The vacuum relay snaps into the programmer.
Thanks for the response. I was able to replace the vacuum relay and reattach everything but unfortunately my heat is still blowing cold. Back to the drawing board.
November 24th, 2011, 09:25 PM
