Comfortron issue

Steve Loftin

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On my 1972 C/B with Comfortron climate control, the A/C works (converted to 134 by a previous owner) and the vents change properly when switched from A/C to heat and defrost. However, even with hot water coming in and out of the heater, there is no warm air blowing.

My mechanic has looked it over and determined that it needs a vacuum motor (perhaps a diaphragm only?) for the programmer. He supplied this diagram for reference. Can anyone here tell us of a source--or at least a part number--for this item?

Or, if there is another common fix for this problem, please share it here. I appreciate your help!
 

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The first thing to check is if the hot water is flowing into and out of the heater core. If it is, then it might be in the programmer, but I doubt it, since the A/C is working properly. The programmer moves the doors by vacuum, and if the upper doors are open, and it calls for heat, then the heat should come out of the upper doors, through the blend door. If it doesn't then I would be looking for a broken vacuum hose.
 
It is a interesting system. The big thing with it is vacuum. The system draces from the manifold to the plastic holding tank. From there it divides to the shut off valve and the controls. It goes forward to the temperature control valve which when it comes up to temp will open the water control valve in the rear. This valve has the thermal switch which when it gets hot enough will put power to the blower motor. One hose leaking will not let the system work. Depending on the spot it leaks at which set of controles work or not. You really or at least i did need the shop manual to figure it all out. There are two separate relays for the blower and the temp wheel has a thermal control on it. Contects need to be clean in the control unit . Not then at time i have to rotate the temp control all the way up to get it to switch then back down other times slide the fan / posision lever back and forth to get it to make the switch. The systen takes some playing with.

But it sounds to me like the water control valve is not working. Both hoses will be hot due to back up temps. Make sure it is opening and water can flow. New control valves are still out there I have gotten two off e bay not that long ago. But the big thing is all the lines run as the factory set them is nessary for the system to work
 
72

Chk and double chk all the vacuum lines for routing ,connections and leaks. Fixed a few of these with just one bad vacuum line.
 
As pointed out the whole system DEPENDS on vacume. Find where it comes off the intake manifold start checking there and follow the hose to its next junction look at each joint for vacume a minor hose kink can cause a problem as old soft hoses kink easily. The thing to remember as an engineer told me years ago"We never designed things to work after 25 years". So this is what you are up against. We fixed a Cadillac years ago for heat in the winter by running a vacume line right to the valve and you just had heat all the time.
 
Myty-Vac hand vacuum pump is helpful also. Harbor Freight sells them for around 42 bucks. They are also helpful when replacing brake lines or hoses for removing trapped air.
 
Update

My mechanic says I definitely need a vacuum motor and maybe the vacuum valve. Can anyone here tell us the part numbers for these items, and possibly a source?
 

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One may have to take the valve apart and lap it in and re grease it. I cured the can't cool problem in my vacuum motor with a new vacuum line. But it could be a pen jamming it.

But i have not found a source for parts for the system. One might inquire with the Oldsmobile group. Let me know if you find one.
 
I posted the same request on the OCA Facebook page, but with no results so far.

I'm told that the complete control unit (as seen in the diagram) is readily available, but will be around $500 installed. The mechanic said that the two items circled are supposed to be available individually, but that without part numbers, he has no idea of looking them up.

Still working on it...
 
WE had many of the GM climate control cars in the day MOST problems were vacume lines NOT parts. Do yourself a favor don't spend big bucks for parts you may not need. Best example of what I am saying was a 66 Cadillac Convertible we sold in early 68. The new owner had it about eight months and came storming in with a "you sold me a piece of s*** the climate control stopped working and the Cadillac dealer says it needs to be rebuilt and the cost about $850.00". I calmed him down and said we would get it repaired. A quick underhood check showed nothing a look under the dash a vacume hose off on the firewall temp sensor. Hooked hose up unit working fine. Find out what is wrong don't just throw parts at it. I will bet its a hose issue. A vacume gage will tell you a lot.
 
Vacuum hoses were checked first and found to be good.

We've had no luck finding the individual replacement components. The garage I use did a nationwide GM parts search and found three NOS complete climate control units, priced at around $400, $535, and $1,000. We missed the least expensive one, so I but the bullet and ordered the $535-ish unit (plus labor; from somewhere in Washington). It comes with a 30-day warranty, so I hope it works.

I only plan to do this once. If this one fails, I just won't drive the car in cold weather--OR--I'll use the old "golf tee to plug the vacuum hose" method of switching from A/C to heat.
 
The garage I use did a nationwide GM parts search and found three NOS complete climate control units, priced at around $400, $535, and $1,000. We missed the least expensive one, so I but the bullet and ordered the $535-ish unit (plus labor; from somewhere in Washington). It comes with a 30-day warranty, so I hope it works.

There are actually two of these NOS complete units available at the middle price--$518, actually (plus shipping). Is anyone here interested in the second one?
 
The shop I'm using has been in business since 1959. The current owner started working there (for his father, the founder) when he was 13.

Here's what they are using to diagnose and repair the climate control system:
 

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The book is handy. I used the factory service manual on the first one walk threw what should do what to what to get this to do that. Way more complicated the nessary.
This other one up here they bypassed the factory controls pot in a toggle switch to engage the compressor and another one to turn the blower on. The only good thing they did was install a pressure switch to shut off the compressor if it gets low. I may never get it stright.
 
Success!

In case anyone is interested, the Comfortron is now working just like it's supposed to. I hope it lasts for a long time...
 
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