I’m in the midst of replacing the vacuum lines on a 1966 I bought a few months back. I’m struggling with the service manual manual and the files I have downloaded, see below. All of them are different in some ways and don’t match my car. I’m struggling with which one to use as they seem different in what I think are fundamental ways. Also, none of the components have part numbers on them for identification, so it’s hard to discern what is what - the vacuum relay as one example. I searched this site and the broader internet for images and such to help, but I’m not seeing anything that applies directly to my car. Any guidance on this would be appreciated. Lastly, there is a component under the driver’s side fender, to the rear of the vacuum tank that is not in any diagram that I can see. It has two vacuum lines going to it and is spherical in shape. I took two admittedly poor pictures of it, they are at the bottom of the set below. Any thoughts on what this might be? Thanks

 

For starters, I don't think I'd be using the '65 Comfortron manual on a '66 car. There's bound to be differences.

In your vacuum diagrams, one has four lines running off of the master switch and uses a remote bleeder valve. The other eliminates the bleeder valve and replaces the vacuum line at the master switch with a sintered metallic plug. I only have experience with the non-bleeder valve system and I know bad things happen if the metallic plug is missing.

I would put hands on a '66 Olds shop manual (Toronado section is in the back) and go by that. I would also put hands on set of '66 service bulletins. They updated things as the year progressed. I know that metallic plug is addressed in a service bulletin (or an issue of the Service Guild).

The vacuum tank in your photos could be for the vacuum trunk release.

 

Not sure I can help, but I’ll try. My ‘66 Starfire has A/C, my ‘66 98 has only a heater since it’s a convertible and, well, if you’re hot, put the top down. At least in San Francisco.

What’s below assumes your basic A/C system stuff like your compressor, blower motor, Freon filling, heater core, condenser and evaporator work as intended by GM. You can still find the blower resistor to control fan speed on eBay if you dig around, just in case yours has broken or rusted out.

That big thing on your inner fender is probably a vacuum reservoir. If it has 2 ports and is either metal or Bakelite plastic its job is to hold a little or a lot of reserve vacuum. To test it, use a carb vacuum plug on the small port and then pump up the big port and see if your vacuum gauge holds steady after probably lots of pumping. If it’s steady, the reservoir is sound, if it leaks down, find and plug the leak. A compressor pumping air into the reservoir while submerged in water will show you where the leak is.

Design
Comfortron was an automatic climate control system that was installed in Caddies, Olds and probably other GM brands. The idea was that sensors in the dash and under the dash would read the ambient temperature of the cabin and adjust the heat/cooling system to whatever temperature the driver desired. The manuals refer to these temperature sensors as transducers, meaning they converted a temperature reading into a voltage signal that told the system to do something. Not quite 60 years later, these transducers may be giving no signal, the wrong signal or might work fine. Whatever voltage they feed in was acted on by some logic-board equivalent or electrical gizmo which translated the signals into actions executed by vacuum diaphragms to effect the desired temperature.

Common Problems
The vacuum control rubber diaphragms can crack over the course of 60 years, so one check you can do is manually pump each one up & down with a hand vacuum pump to see if they leak or work properly. Give each one a good pump up until the needle on your gauge holds steady and you should see some physical movement in whatever arm the diaphragm controls. If not, well the diaphragm leaks, or has a hole.

Vacuum System Complexity
The vacuum dia_grams_ (diagrams, not diaphragms), are devilishly complex on this system. Any of your nearly 60 year old vacuum hoses could have cracks or leaks. The cracks are most commonly found near or on the nipples the hoses connect to (especially the tiny color coded ones - GM made ‘em long to allow mechanics to snip off a .5” here & there to maintain vacuum integrity).

A Repair Approach
This many years later, if it were me, I’d get all new hoses and color code each hose on the bench with the name of the line with a label - “Purple”, “Orange”, “White”, etc. Color code both ends of each hose to create replacements you can count on - and cut ‘em all about 3” too long to allow for future maintenance. Rubber didn’t get better in the last 60 years, you’ll eventually need to snip these lines for maintenance too.

Dash Controller
Beyond the stuff in the engine bay, you’ll have to deal with the vacuum controller located in the dash. The piano keys basically just operate a rotary vacuum switch which directs vacuum where it needs to go based on rotary switch rotation. This switch, as designed, didn’t have the greatest vacuum integrity. That’s a nice way of saying it leaked a bit by design. There’s a wool/fabric washer which is supposed to hold the 2 sides of the rotary switch fast (close), but as it wears, it gets loose so eventually you get a vacuum leak at the rotary switch on the left side. I’ve used “high vacuum” grease to seal my non-comfortron system to good effect. But if you get into tearing it down, clean and grease everything in there. I use #0000 steel wool.

From what I know about comfortron, the temperature dial seems to have some kind of clutch mechanism on it which will need to be calibrated. How to do that in 2024, I don’t know. My simple A/C is just set the slider to “Cool” which cuts off the heater core in favor of the evaporator cool air and then you just decide how much blower you want.

Warmly suggest you check around Cadillac forums for this system. My impression over all these years of Olds ownership is that they might have worked well from factory, but don’t seem to have held up well long, long after these cars were expected to be in the boneyard. I’ve toyed around with upgrading my ‘66 S/F to comfortron, but I think I’d need 3 donor systems to have a chance of getting 1 properly working system in my car.

Wishing you good luck on this project, suggest you keep digging and find some donor cars - Olds or otherwise.

Cheers
Chris

 

Thanks for all the replies. I had the shop manual but was not looking in the back. One of the pictures I showed above was the right one and aligned with the 1966 SM in the 94 and 96 series section. I ordered the colored hose kit and replaced all the hoses in the engine bay, splicing some so I didn’t have to disturb what was in the interior of the car, as that all looked good and weirdly, original. In the engine bay, all the components were there, though not plumbed exactly like the diagram for 1966, and this was difficult to understand at first given the condition of the system and its components under the dash. Going back into the car, I traced all the tubes to each component and found them all to be where they should per the diagram, giving me confidence I was using the right routing diagram in the SM. I found a few loose connections and was able to cut the ends off of them and reinstalled to get a better connection. Some of these seemed to be plasrtic hoses and didn’t want to go on and were persuaded with a little blast for a heat gun to soften them up before pushing them into place.

I also found some connections were not great and given the voltages and currents involved, these may have been an issue, I was able to address these with some new connectors and some cleanup - the transducer looked almost new and was properly grounded. I’m sure there will be other issues and once I get the exhaust manifolds installed (needed to be dressed at the engine interface and have a crack addressed on the passenger side, this should fix my exhaust leaks) I’ll be interested to see what I get.

 

I know this is an older post, but I see that dean halter ordered a comfortron colored hose kit. I've been looking for one of these. Can anyone tell me where this kit can be purchase? Thanks.