Author Topic: 1969 CAD deville A/C TEMP DOOR PROBLEM  (Read 204 times)

Offline 1969cadillac

  • Posts: 124
  • Name: murray mules
1969 CAD deville A/C TEMP DOOR PROBLEM
« on: October 24, 2017, 10:21:22 PM »
Hello out there again.

I have a 1969 deville hardtop. The temp door on the A/C will NOT adjust correctly

I did a wedding in this car last Feb and noticed that towards the end of the day the A/C was NOT getting cold .At the start of the day it was somewhat cold , but at the end of the day only HOT air!!

A good friend of mine hooked up his A/C gauges and the pressures were ok.

I then had the idea of pushing the link that is connected to the temp door - pls see Images attached. The air inside the car definitely got colder....

I then tired to adjust the link turning the small screw , but from memory , after a while the link goes back to its original setting.

I then pulled the large central vac hose off the power servo and the link went to maximum and the air got very cold!!

A friend of mine suggested that it could be a sensor problem ...

Any suggestions would be appreciated ,

Murray Mules
« Last Edit: October 24, 2017, 10:34:51 PM by 1969cadillac »

Offline "Cadillac Kid" Greg Surfas 15364

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Re: 1969 CAD deville A/C TEMP DOOR PROBLEM
« Reply #1 on: October 25, 2017, 10:06:46 AM »
Murray,
Get yourself a factory service manual and start from there. The FSM has the control circuit wiring diagrams and shows the sensors with the temperature vs. resistance values. 
Could be anything from a sensor issue to an amplifier glitch. Check out the sensors first.
Greg Surfas
Cadillac Kid-Greg Surfas
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Offline Jeff Rose CLC #28373

  • Posts: 1405
  • Name: Jeff Rose
Re: 1969 CAD deville A/C TEMP DOOR PROBLEM
« Reply #2 on: October 25, 2017, 01:47:12 PM »
Basically think of it like this..... from memory.
It wants to go to max cool. That is with no vac going to the firewall module. As you add vacuum, the arm on the power servo moves and adjusts the temp door to gets warmer and about halfway it will switch from blowing out the dash to the floor. The fan speeds will also change and get lower towards the middle of the travel and then increase.
The car has 3 sensors that measure the temperature and convert temperature to resistance. That is compared to what you have on the dial. If it thinks that you need it warmer then it will send voltage thru a transducer that in turn adds vacuum and starts the cycle stated above.
That is how it works, albeit very simplified
I think cold adds resistance. Since it gets warmer the more you drive and if everything else is working correctly then you are having resistance added as you are driving. I would look for loose or corroded connections at the sensors and go from there. I think they are in the passenger footwell, center section and that vented spot on the dash just in front of your face.
With that being said, don't forget this thing was made before man walked on the moon-and the design was well before that. Do what Greg says and get yourself a manual.
I am sure others will chime in and correct my "memory." I did this once before but it was for a 71 I think which was different. I think 69 and 70 are just about the same tho.

I am sure you will understand how much pleasure it gives me to type this considering mine doesn't work!! Oh well.
Jeff
« Last Edit: October 25, 2017, 01:58:12 PM by Jeff Rose CLC #28373 »
Jeff
CLC #28373
1970 Coupe DeVille
1955 Series 62

Offline dplotkin

  • CLC# 26299
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Re: 1969 CAD deville A/C TEMP DOOR PROBLEM
« Reply #3 on: October 26, 2017, 07:01:58 PM »
I'd be looking for vacuum leaks or related mechanical problems before I looked at sensors and the like. Anything nearly 50 years old with a diaphragm operated by air or the lack of it would seem to me to be a likely culprit.

Dan
56 Fleetwood
60 Buick Electra six window
61 Plymouth Savoy Ram Inducted 413 Superstock
62 Pontiac Bonneville Vista
63 Chevy Impala convertable
63 Ford Galaxie XL fastback
65 Corvette convertable 396
68 Chrysler New Yorker

Offline cadillacmike68

  • Posts: 1139
  • Still finishing up this 1968
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      CLC Member #15823
  • Name: M Santos
Re: 1969 CAD deville A/C TEMP DOOR PROBLEM
« Reply #4 on: October 28, 2017, 10:36:19 PM »
Unless you have a broken wire, the sensors (which are just lead dots in the middle of the wire) almost Never go bad.
Regards,
"Cadillac" Mike
Current:
1968 DeVille Convertible
1996 Fleetwood Brougham
2009 STS NorthStar Platinum ed RWD
2011 CTS PRemiun ed Sedan RWD
Past:
2008 CTS Premium ed Sedan AWD
2005 CTS Hi-Feature Sedan RWD
2000 ElDorado ESC Hard Boot Convertible
1995 Fleetwood Brougham
1973 Sedan DeVille
1970 Fleetwood Brougham
1969 DeVille Convertible

Offline 1969cadillac

  • Posts: 124
  • Name: murray mules
Re: 1969 CAD deville A/C TEMP DOOR PROBLEM
« Reply #5 on: November 09, 2017, 03:56:51 AM »
Hello out there . The problem with the AC turned out to be a bad connection on the sensor in the attached picture . It is in the left footwell area. I also checked the vac connections under the dash and all seemed ok.

All good now ! Thanks for all your help and guidance

Murray Mules

Offline Jeff Rose CLC #28373

  • Posts: 1405
  • Name: Jeff Rose
Re: 1969 CAD deville A/C TEMP DOOR PROBLEM
« Reply #6 on: November 09, 2017, 04:10:33 PM »
Thanks for the update. I like when people post their fix.
Jeff
Jeff
CLC #28373
1970 Coupe DeVille
1955 Series 62