66 Cuda HVAC control problems

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LP1966

LP1966

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I am restoring a 66 Barracuda 273 and am having problems with the AC controls. Here is what I've checked so far:

- All vacuum actuators, and AC, Heat and Defrost doors are working when hooked up directly to vacuum lines. Push buttons move freely in and out. Heater valve control cable and valve itself work. Fan switch and blower work (although blower motor is on last legs)


However, when I hook the vac lines up to the dash controls, everything works except when I push AC or MaxAC, the door for the AC opens, but after that it will not close. If I push Heat or Defrost, the AC doors stay open, with no air to heat or defrost.

Any suggestions or comments would be appreciated. Thanks
 
Leak in the control switch? I'd rustle up some vacuum tees and short lengths of hose so you can "rig" your vacuum gauge to different points and see what you have.
 
Thanks 67Dart.
I'll try that next and let you know if I can isolate where the fault is.
 
I have no real info about these old girls.

You have one of those test hand vacuum pumps?

41ZR4KBYaUL.jpg
 
Double check that vacuum servo. Some of them have vacuum both ways instead of vacuum one way spring return the other. Could be a failed return spring.
When a servo has vacuum both ways ( like the one at the water valve ) the vacuum that was applied one way needs to be vented whenever vacuum is applied the other way. If you had a unused port on the switch and thought it best to cap it... you probably blocked the vent.
I'm not sure when they started adding the porous stone that served as a muffler for the vent.
 
I had a similar problem years ago and purchased a NOS switch module on ebay. The old switch was leaky with vacuum. The vacuum connectors are also fragile.

The max setting boosts fan speed. Poor bulkhead connections mess with fan speed, the current requirement is significant.

I also found the water shut off valve worn internally from use, and and also replaced it.
 
67 Dart, I dont have a vacuum test pump.
I have heard about a vacuum tank - there is not one on this car but should there be? Also, does an inline, one-way vacuum valve help?
KitCarlson, is the "vacuum connector" you speak of the 7 pin (a row of 4 and row of 3) one in this thread - http://www.forabodiesonly.com/mopar/showthread.php?t=235757

I found a NOS switch on ebay
http://www.ebay.com/itm/NOS-MOPAR-1...d=100005&prg=1088&rk=1&rkt=4&sd=190792967403&

will this work as a replacement for mine?

Thanks
 
Where the servos are vacuum operated both ways , the vacuum reservoir isn't required. Reservoirs compensate for temporary lack of sufficient vacuum where a servos spring return would occur.
 
That switch looks similar but not sure. I will look in my box of parts to see if I kept the old one and compare. Yes the vacuum connector is like that. The pins are brittle and break, resulting in leaks. Mopar kept similar design for many years.

I looked and I think I remember tossing it after taking it apart, it was beyond my repair, I seem to remember erosion in the electrical switch parts, and other wear. Perhaps someone will know if a later switch will work. I seem to remember it is a chore to replace. I have big hands, and needed to pull the glove box liner, radio and lower A/C vent system to work. Those are all easy to do, so not to worry. I m old enough not to be flexible, nor see well under dash. I think the choke type cable on the temperature slider gave me grief.

About the vacuum canister, my car does not have one, and A/C works fine. I have seen 66 B'cuda cars with power brakes, and the vacuum canister mounted on the drivers side near the washer reservoir.

I just spotted a used switch: http://www.ebay.com/itm/1960s-chrys...Parts_Accessories&hash=item2eca5fedbe&vxp=mtr

This one calls out 1966 - 1973: http://www.ebay.com/itm/Mopar-NOS-A...Parts_Accessories&hash=item5654942fdf&vxp=mtr
 
Thanks everyone. Here is what I've done so far:

1) removed the old switch and found 2 of the 7 pins on the vac connestor missing.
2) found an ink pen with a similar OD size ink barrel (the ones on the switch are .130", and I found an ink barrel with .125" OD)
3) drilled out where the pins were broken off (be careful not to drill too deep - on one of these I drilled all the way thru, so the only support for the replacement pin is a snug fit and Gorilla Glue)
4) glued the new pins into place.

I'm letting them set up overnight, and will report tomorrow what happens when I re-install the repaired switch.
 

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I was just about to post almost exactly what you did, I removed my switch fished the broken ends out of the hoses and glued each of them back on using .032 safety wire in the holes as guides and disassembled the fan switch cleaned it up [internally] and reassembled it that was 7 years ago still works great!!
 
Somebody that actually "fixed" something? We can't have THAT LOL
 
update:
I installed the repaired switch. Everything worked find until I pushed the Defrost button, and the door would not move from Heat position. It goes from AC, to Max AC to Heat, but no Defrost. Hmmmm...

I think that when I drilled that one hole all the way thru, thus making a really tiny hole into a big one, I may have messed up some kind of balance with the vacuum. Either that or the vac switch itself for the defrost door is bad. That switch is way up behind the wiper motor. I think I'll let it stay there


So I have temporarily rigged the defrost door so it does not close completely, i.e. Heat and Defrost will be on at the same time. It'll take a little longer to clear the windshield or warm my toes, but it's an acceptable solution for now.

What I am most happy about is the sturdiness of the repaired vac connector pins. After several connect/disconnect cycles, they and the Gorilla Glue held up fine. Thank you to Bank of America for involuntarily donating the pen I used :wink:

Thanks again everyone. One day I may actually get to drive it.

ps: good suggestion from lou3500 - use something to keep the holes open when gluing the replacement pins.
 
OK, so I rebuilt and then re-rebuilt my old AC control switch...each time something different would not work. Out of frustration, I bought this switch
http://www.ebay.com/itm/160642617456?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
I had to wire the 3 terminals differently, but it works perfectly. I did not write down the pin-out/wire color for the new switch, but with the wiring chart from 67Dart273 it was fairly easy. However, I hope I never have to get under the dash again...my body does not twist that way anymore :(
I can now drive the Cuda for the first time since August 2012...next step is to look in the carburetor section.
 
Well you're makin' progress, at least. "I'm nearly depressed." Just got done tearing the 67 down, it's going to the media blaster guy next week.
 
67Dart273 - good luck with the 67 renewal...that's a lot of work. keep us posted.
 
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