Noted. I want the machine shop guy to drill out the rivet and tap the old rivet head (large side) for the screw that will replace it. I intend to do the re-surfacing. The valve on the power piston side looks real good and has lubricant in it. I imagine it is still good, but I'll re-surface it anyway-a little bit. 

Thanks!

I'm really stumped on where to tap the threads for the 4-40 screw and whether to try to do it in a way that holds the original arrangement with a rectangular clip that holds the rivet head on and provides tension between the halves. Has anybody done this repair? If yes, how?

Thanks

That's pretty close to what we're doing. We are doing this in such a way as to be able to re-use the spring to provide tension, as before. I'll take pictures. THANK YOU!

Norm

PS: In high school metals shop we were shown two identical pieces of metal that had been milled and finished so perfectly that when pushed together they stuck, and were very difficult to separate. So, I hear you re the tendency for the two halves to hold together without a rivet. 

To be clear, it is what we're doing for the valve on the control side, not the power piston side. I re-surfaced that one (power piston one), lightly greased it with vaseline and will be re-installing it tomorrow. 

Dumb Question: On the 7 nipple vacuum valve that goes on the POWER PISTON side: I cleaned and re-installed the valve but noticed on the bottom (where it interacts with the plastic-tipped arm) that the valve has both a nub and a pointed, narrow arm. Which one is intended to slot in to the fork in the plastic spring-loaded arm below?

Thanks

Pictures? We don't need no stinking pictures. No, I didn't. We'll see when I get the control side valves back from the machine shop and I install one. 

N

Pictures? Here are pictures of the re-furbished valve with a new center and screwed in bottom

OK, Vacuum valves restored and installed.  Now all the vacuum doors (Except the AC RECIRC) operate properly, but the air is not going through either the AC vents nor the heater vents. Yes, the blower is blowing strongly-but air is backing up (going the wrong way) at the blower cage inlet. In other words, instead of being drawn in to the blower cage up top, it is being pushed out. I think the primary feed duct under the hood is blocked. We'll see.

Note: AC recirc door is bypassed, so there is no leak in the vacuum system. 

Something doesn't add up if you do not get air coming out of either AC Ducts or Floor heater ducts. I am sure you have studied the air flow diagrams and see that with any combination of the air inlet, temperature and mode door, that air always has an outlet.  When the blower motor and air inlet is working and blower motor is turning you have a very strong flow of air out the side feed via the metal duct to the evaporator. It doesn't matter where the air is pulling from up top (i.e. in the cabin or outside from the cowl) it blows strong air. I just pulled a blower motor and air inlet assembly and tested with 12 volts and it puts a strong force of air out the side. So, my guess is you have the wrong motor that is turning/blowing the wrong way, or you really have something jammed up there somewhere that is preventing the air flow from blower motor, to evaporator, to inside air distribution box.  I would be curious how this resolves. One thing you can do, is  remove the double halved blower motor evaporator metal duct and stick 12 volts to the motor and see if you get a strong current of air out that side feed!  If you remove the motor and just bench test it, it turns counter clockwise looking down from the motor end toward the cage.

This is what I was originally referring to when I said I thought my blower motor was reverse wired. This car does not  look like it has ever been apart, so I am inclined to go with the blocked duct. I can reach the blower cage and feel which way it is turning, I just didn't make note of it. I will now. I get just the slightest hint of a breeze out the AC vents when AC is selected and a slight hint of a breeze out the heater outlet when heat is selected. But I mean BARELY PERCEPTIBLE, so I like the blocked duct theory. I took off 4 of the duct bolts (the upper ones that attach to the split duct that leads immediately away from the blower motor) and there's a breeze there. This is getting annoying, cause I can see the power piston arm move from cold to heat and vice versa. I have not done any electrical evaluation yet as I am concentrating on air flow. Wish you lived closer!

When you say double  halved duct, I think I know what you are referring to and it has lower bolts that are likely reached by taking the inner fender inspection panel off. Right?

There is only one metal duct that feeds from the blower motor and air inlet over to the evaporator. See the duct circled in yellow below with green arrow pointing to air flow direction:  You stated in your last reply "I think the primary feed duct under the hood is blocked." I assume this is what you are referring to as it is the feed duct to the evaporator and into the air box once it goes through the evaporator. As far as removal, it will probably be easy just to remove the blower motor, pull and bench test. Regardless if you put 12 volts to the connector at bottom of motor it should be pushing a very strong flow of air in the direction of the green arrows in pictures below.

Yes, that's the duct I have been referring to. And, yes the blower blows strongly. When you referred to it as "halved" I thought I could pull of a section of it to either directly inspect or put my camera down to see if it is blocked, which is what i expect. With the fenders and hood off, it looks easy but with the car intact it is a bit tricky. I am going to try to remove more bolts.  I took the top 4 off that duct, which allowed it to open and I did feel a breeze. If I can get more of it open or off entirely, I can inspect and vacuum it out if necessary. 

How difficult is it to remove part of that duct. Removing the motor looks like a bigger job, and I have reason to believe it is good and installed correctly. I think I have a blockage.

I used the term "halves" to be consistent with the wording in the shop manual under Blower Inlet Assembly removal where it references removing the duct (see below). There are just s series of 1/4" screws at bottom of motor holding it to case. I would just take a light and look both blower motor screw, or the duct halves bolts and nuts. Either will take a bit of effort but not that bad.

Two things will be a deal breaker: 1) If I have to remove the hood hinge (too inexperienced to know how to properly brace the hood), and 2) The AC line is directly below the blower motor and is just long enough to to to the expansion valve, meaning it may not have enough give to get it aside to let the motor drop out. Because the refrigeration system is working properly, sports a rebuilt compressor and does not seem to leak I am VERY reluctant to evacuate the system and move the hose. I will think on this and hopefully figure something out. THANK YOU!

Anders: I cannot fault your logic. 

Unfortunately, most of the old time workshops are gone; owners retired or died and the younger folks don't want to/don't know how to work on stuff like this. There's probably a place that will do it, but I have not found it yet. I prefer to do it myself because I like to learn about it first hand, however as I've aged I now have certain limitations on what I can accomplish. 

Will be getting to this again in the next few days and will keep posting. Meanwhile, thanks for the input.

VERY good suggestion.

About the "old man" thing: Don't know how old you are but you will see that as you age physically, you will still be at a certain mental set-point between your ears. For me, that's 17 and coincides with when I first drove cars like this. So, it may be an inconvenience but after having way over 100 old cars over the years I'm not about to stop now. And, with a great group like this to support me, I'll figure this out. Stay tuned, and keep the suggestions coming.

Quick question: Which way is the blower cage supposed to be turning (from the vantage point of looking DOWN on it), Clockwise or Counter Clockwise?

Thanks.

As noted in my reply yesterday "it turns counter clockwise looking down from the motor end toward the cage."

Thanks. Guess I better read more attentively. 

OK, looks like the motor is spinning CLOCKWISE so somebody crossed a wire somewhere. I will start tracking down that circuit.

THANK YOU!!

To anyone's knowledge is there an electrical fault that can happen that can reverse the polarity of the motor, or is this likely something that has to be tracked down?

I promise to read every answer carefully.

To make absolutely sure we are on the same page regarding spin direction I have inserted a picture showing the rotation of the blower fan looking down toward the blower cage end:

Good thing you did this. That appears to be the motor and casing that when mounted in the car gets flipped up, so that the "4-64" would be on the bottom, and the open area it is currently resting on would be facing upwards. In that condition, what is moving counterclockwise in this configuration would be moving clockwise when turned upside down, like when it is installed. My motor cage  is turning correctly. 

Norman, As I indicated "it turns counter clockwise looking down from the motor end toward the cage", which is the orientation in the picture. When you have the motor in your hand, look straight down at it as seen in this picture, (which would be looking up from underneath if mounted up in the blower motor case assembly) it is turning counter clockwise as noted by the arrow in my picture.  Regardless of how you characterize it or word it the fan cage blows in the direction of the arrow in my picture. If your motor is turning in this direction, it is correct. If it is turning in the opposite direction it is incorrect. 

Yes.

So, the motor is turning in the right direction, which means there must be a blockage down the line. When I next have the time I am going to try to remove the duct parts (after taking out the inner fender liner for better access) and see if the duct passageway is blocked, which I now believe to be the case. Thanks for the encouragement and clarifications!

Making progress. Inner fender removed;duct loosened; strong breeze felt in the duct. Motor working correctly. Must be clogged Evaporator. Need small light on a stick to insert in to duct (can't remove it because hood hinge is in the way) so I can insert my camera on a stick to inspect the innards of the duct work where it meets the evaporator.

Yes, the hinges are a recurring theme for me-the stuff that nightmares are made of.

I managed to take the duct apart, but not out.. This enabled me to put my camera inside; beautifully clean. Then, I went inside the car and stuck the camera in the heater duct work, again beautifully clean. Somewhere a door is not opening or something is stuffed where it does not belong. I also figured out that what I thought was output from the fan was, in fact, INPUT TURBULENCE. DUH!

So, now my concentration will be on the ductwork and maybe the heater core. We'll see.

Gotta go  shower and tend to my wounds; the farthest screw on the bottom of the duct is a real nightmare to reach-even with the inner fender removed. 

OK, blower works. Air reaches the bottom of the outlet  (square, insulated large connector that exits the evaporator) but won't come out of anywhere. There's air leaking all around that area, but that's easy to re-insulate and contain. So, I disconnected the arm on the power module that interacts with the heater/ac door and moved it manually; I do get heat through the heater ducts (and hot air through the AC vents) because it blows when I manually move the lever. I think the arm on the power module is not moving far enough (it IS getting correct 10 in of vacuum) and/or the temp wheel is out of calibration because it favors ac, not heat (meaning the arm does not move far enough to engage the slower heater speeds and the arm does not respond to control wheel heat requests until way up in the 80's on the wheel). So, I think at least I need a good power module. Where to purchase, please?

VERY good point, Clovis. I'm going to think on it and play with the system some more, then test the power module like the book says, but I am liking the idea that the arm is not traveling far enough; it only goes on HI heat, no further. If your theory is correct, it would stay on low heat if anything (it is in the mid 70's here). 

EUREKA! I'VE FOUND IT!

The Power Module will not cycle past the first two positions no matter how much vacuum is applied.The spring tension on the arm is so great, the bellows cannot overcome it.  This and a leak around the main duct seal appear to be the  culprits. Now, to have it repaired.

In short, yes; but it holds a certain amount of vacuum before it won't hold enough to travel to all positions required. It was your post that got me thinking about what the system would be doing in this weather. It occurred to me that if it was already warm in the car, the most I would get out of the heater setting would likely be LOW fan on heat-because the sensors already detected the hot air in the car. So, as I watched the arm travel from AC to Heat, I realized it was not traveling very far. Then, I disconnected the traveling arm from the heater/ac door rod and moved it manually; it resulted in an air stream where I needed it. So, I took the power servo (thanks) off to see what would happen if I fed it the correct amount of vacuum (10 in) with my pump and took off the protective cover so that I could watch the arm go to each of its required electrical stations. It won't. The spring tension it has to fight in order to get to the last 3 or 4 stations is so severe it cannot overcome that tension with vacuum-partly because it is a strong tension and partly because I think it has a tiny leak, but just tiny enough to let the bellows retract a bit before it stops responding. So now I am going to concentrate on getting the power module rebuilt and sealing the leak in the plenum. Thanks!

As much as I respect Tim Groves Diagnostics book, the very 1st thing I will do when I do my "deep dive" into my Comfort control system is test ALL vacuum actuators and vacuum components before I do anything.  This will include the mode door actuator, recirculation door actuator, power servo diaphragm, transducer, and Suction Throttle Valve. If any of these will not hold 15 to 20 inches of mercury it will not matter if the power servo or dash control rotary valves are good or if you have replaced the old loose fitting vacuum  hoses with new nice tight-n-snug hoses. I would say 95% of the recirculation actuators I have brought in have been busted, 2/3's of the STV's, transducers and power servos do not hold vacuum. Only the mode door actuators tucked away inside the air box, is the only one that seems to have a good survival rate!

Agreed. Only thing is the Heat/AC door is actuated by the Power Servo, not its own solenoid. As I became more familiar with how this system works, it slowly dawned on me that its malfunction was a possibility. When I disconnected the power servo arm from the Heat/AC door rod and moved it manually I saw that it had LOTS more travel in it than what I observed when the power module moved it. That was the key. 

It was a moment of triumph (I hope). I very much enjoy the comments, encouragement, knowledge (and even the occasional ribbing) from members. While I have had lots of Caddies with Comfortron (2 65's; 3 66's; 2 67's; 2 68's) I owned them mostly long ago, when the Comfortron systems worked perfectly, so the most I ever had to do was on one of my 67's where removing the vacuum restrictor restored operations to new. More on this project when I have it to report.

I won't tell you how old I am, but I will tell you that when I hear the word "NIKE" I think of a missile, not a shoe. (google it)

Update: I sent my Power module and a spare Transducer in to Classic Auto Air in Florida. Rebuilding BOTH parts comes to around $200. Hopefully, the hurricane won't hit them and I'll get my stuff back in about 2 weeks, working like new. Fingers crossed.