I know this question will probably bring back nightmares for some but.....
Has anyone ever had any luck fully rejuvenating a Comfortron system? I have '70 98 and have been able to use an override switch for the blower to get heat/defrost. I used a vacuum pump on all the diaphragms and the master switch and they all held and the doors they operated worked as designed. I just can't get it to work in harmony. Only the heat and defrost doors work normally. I can see the outside air door move initially but then it stays up. I need to check the controller but it's buried under wires and Nightwatch. Any pointers would be great.

 

One of the Dealer Essential Service Tools was the Comfortron Tester if that tells you anything. A retired Olds Zone Service Manager once told me half their Zone level work 66-73 involved trying to get Comfortrons to work, and some of the jerryrigged stuff you find may have actually been a result of that...

The Olds Comfortron parts used to be common on ebay ten or so years ago. NS about now.

 

That doesn't sound promising. At least heat and defrost will work. Only problem is the heat is uncontrollable, only super hot.

 

If your windows go up and down problem solved, sometimes you have to compromise with a full size Oldsmobile...... Lost in the fifties.... Tedd

 

I've worked on several Comfortrons, the biggest problem as you are finding is to gain access to the controller, servo and amp. I've found the amp defective (system stuck in heat mode, hi fan speed), the servo/wiper arm burnt (no speed change but changes from AC to heat), or the vacuum mode switch (weird or subtle problems or sluggish operation). I'm not sure how it is on a '70 98, but if it were me, I'd pull the underdash Comfortron guts and go through each piece on the bench. With a 12V power supply (don't use a battery charger, too much ripple) and a vacuum pump, you can do a lot of trouble shooting on the bench - saves the aggravation of trying to work on it in the car. With it on the bench you can also replace/adjust other things like door foam gaskets, etc. PM me and maybe I can help with the troubleshooting. Thanks, Karl

 

I found a NOS heater valve/TVV and was able to replace my original. The blower master switch started activating by vacuum. I'm able to disconnect my jury-rigged switch under the dash. The old valves vacuum ports were completely blocked. I still can't get it to switch to the dash vents automatically but at least now heat and defog work without a switch to turn on the blower. Still no outside air, just hot air, but progress is progress with this system. Once I figure out how to get the panel out maybe I'll make more progress.