Author Topic: Climate control system questions  (Read 821 times)

Offline dst2680

  • Posts: 31
  • Name: D Starna
Climate control system questions
« on: June 29, 2014, 08:08:01 PM »
With the help of previous posts, I discovered that the ticking sound behind the glove box in my 1975 Coupe deVille is stripped gears in the climate control module. I removed the glove box and and watched the metal rod at the top move as the temperature dial was changed- it was quiet when it was on 90 but as it was turned down to 60, it started jumping and ticking. I have several related questions- how do I go about fixing this? Would the entire module have to be replaced or can I open it up and replace the gears? is this a big repair for someone with fairly basic skills? Where would I buy a replacement module or replacement gears? The heat appears to work great in the car, its very hot but it only comes out on the floor and it will not come through the dash vents. There is no cold air at all, is this related to the climate control module or is this a separate issue like the air conditioning is not functioning? When I move the switch on the dash to various settings like low or high or defrost, no air is blowing hot or cold, it still comes through onto the floor. Is this another separate issue like a blower motor or is it related to the climate control module? I just recently acquired this car so i am still getting to know it and I have never owned a car with a climate system quite like this one. Thanks a lot!

Offline TJ Hopland

  • Posts: 10183
Re: Climate control system questions
« Reply #1 on: June 30, 2014, 03:00:24 AM »
Does your blower speed change when you switch between the various modes?     Have you looked to see if the AC compressor is cycling at all?   If everything is good the compressor will run in all modes except econ (or was it still called vent in 75?) and off.   Blower will run on at least low in all modes including off. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Re: Climate control system questions
« Reply #2 on: June 30, 2014, 03:23:16 AM »
The first thing I would check is the vacuum circuit. Make sure all the vacuum hoses are connected to the correct devices and that those devices (actuators) actually work. A factory service manual is the best guide to follow for vacuum and electrical circuitry. It is possible there is a vacuum line loose in your programmer causing the nlise you are hearing.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
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 cadillactim

  • Cadillac Tim
  • Posts: 798
Re: Climate control system questions
« Reply #3 on: June 30, 2014, 11:11:41 AM »
The ticking noise you are hearing is the programmer "hunting" for the right position.  It is an amplifier/transducer problem.  Sometimes it is in the amplifier circuit where the potentiometer is sending erratic signals, and other times it is the transducer not being able regulate the vacuum properly.

You can replace just the amplifier board (if you can locate one), but you have to know how to calibrate it after replacement.

I have rebuilt programmers available.  You can email me at tagroves@wctel.net or call me directly at 864-352-3306 (SC).

Tim Groves
Tim Groves

Offline TJ Hopland

  • Posts: 10183
Re: Climate control system questions
« Reply #4 on: June 30, 2014, 11:49:50 AM »
I just ordered one of Tim's diagnostic manuals for my car that is doing wacky things.    I have not got it yet but it should be here in a few days and can let you know how helpful it will be.   I do have a shop manual and have been too lazy to look the climate control system up in there.   I am guessing that many of the procedures in there tell you to grab your handy dandy J-whatever official GM diagnostic cart and use it and all its special tools to go step by step through the system.  Tim's book is supposedly written to use fairly commonly available basic tools and with 30+ years of experience on these 30+ year old systems.  The stuff that is failing on them now is likely quite different than what was failing on these things when they were new.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

 

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