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1976 eldorado with climate control issues

Started by 76 cadillac bob, August 12, 2017, 07:40:52 PM

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76 cadillac bob

Cadillac Bob here, almost done with restoration,I wanted to fix CC before new interior fix. The slide switch works see attached configuration.

off - economy -lo -Auto- hi - Bi level -  Def 

Economy - does not turn on compressor, but blower blows high
Auto - turns on cold air high blow whether on lo or hi  (wheel is in Blue)
Bi-level- works,  it throws what ever air I have on through main ports and foot area
Def - works on windshield  so it appears baffles are doing something. Basically one speed. Blows cold air thank goodness, here in San Diego. Thinking relay which is hanging down from dash may be an issue.The whole AC in the engine compartment was replaced last year and works terrific. The temp wheel does throw hot air when it is turned to the RED.
SIDE BAR: I am getting a huge blast from under the dash on passenger side even when CC is OFF,  not sure if a heater baffle is open or is just engine heat as this car runs extremely hot.  The heater valve in the back with hoses attached in the engine compartment is original so I bet that should be replaced as well.
I am checking for vacuum leaks,
I question the CC Controller, and sensor in upper dash (please don't tell me to replace I know how difficult it is) I had the dash pulled once already.
Once again everyones wonderful advise is requested, I don't know what I would do without you. what am I missing?
Regards
CB

STS05lg

Bob,

From your description it sounds like a "Programmer" issue. The programmer is located behind the glove box liner. First check to make sure the multiple vacuum lines connected to the programmer, which controls the regulator doors that direct air to the lower, dash, defrost vents, are attached properly. You can also contact Scot Minesinger here on the forum. He is an expert on the 1974-1976 climate control systems (he has rebuilt two of mine and countless others). Two facts about these systems I have learned from Scot, first if there is a component failure the system is designed to default to high defrost (I think this was for a safety issue to prevent the windshield from fogging up if the system fails), Second, the system has a sensor on the engine that prevents the system in cool weather from kicking on until the engine has warmed up to prevent cold air from being blown out the heater ducts (most everyone has disconnected the sensor because it is prone to failure and will cause the system to not work properly. Again, I only have a elementary knowledge of the system but these are a few tips i have picked up over the years. Again, Scot is really great at helping other members, try contacting him by PM.

Lynn


"Cadillac Kid" Greg Surfas 15364

Bob,
What I understand from your description is that you get cooling when the temperature control dial is turned down and heating when it is turned way up.  You said that you have only the high fan speed, when the selector lever is in Auto, and you slowly roll the temperature control dial from full cooling to full heating, does the fan speed change and does the air outlets activated switch from dash to floor?
The operation of the system is such that at system "off" you get low speed blower providing "flow through ventilation" and it is intended to discharge at the floor level.  If the air flow at the Off position is the same as when in operation at say maximum AC, I would suspect there is either a wiring issue, possibly caused by an inappropriate "modification or repair".
Do you have a factory service manual?  It contains all the wiring diagrams and vacuum diagrams you might need to trace this out.
You say you had the AC "under the hood" done.  What exactly did they do?
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-

Caddyjack

Another potential cause to some of the weirdness could be the electrical connector for the programmer located behind the glovebox. It is very poorly constructed and can easily come loose, resulting in all sorts of chaos and unusual climate control operational miscues. One sure sign of this is if the climate control lever is placed in "auto", and nothing happens....while lo and hi both blow cold air (or hot, depending upon your temperature setting).
Jack Larson
Philadelphia, PA

76 cadillac bob

I have a shop manual  for the car with everything on it, from electrical to body to hoses and screw sizes and torque to use and trouble shooting.
I had a thermal limiter fuse, new compressor, rebuilt receiver / dryer with o rings flushed  and Pressure hoses replaced. The car was already retrofitted for R134 before I bought it. I also had a the connector attached to the right fender well replaced. Basically I am getting cold air on high. At least it is cold.

"Cadillac Kid" Greg Surfas 15364

Bob
What happens when you try the things I suggested above?
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-

76 cadillac bob

the car had to make an emergency visit to the doctor, for continued front end replacements, the parts came in.  We can relate, those joints just dont work so well after so many years I was 26 when my car was new. I will have to suspend this discussion until next week when I can get into it and really test everything....sorry.
I would love more suggestions so I can troubleshoot once I get it back.
CB

76 cadillac bob

Greetings all
OK car is back from getting a new front suspension built, I checked vacuum, and plug to the controller, all ok and tight. Temp  wheel does not change temp cold to hot it just blows AC or on Economy=regular air. HI LO do not change. The bi level works, and so does defrost. No heat. The thermostat on the back of the engine block below the wiper motor is broken so the wire to it is dangling. I believe it is for the cold start up but not sure.
AC works great on cold.I have the glove box out and the lower dash below steering wheel is off. Is there a relay I should check or ?
the only thing I noticed behind the glove box, two wire set with nowhere to go. One pink single wire and one green orange and white three wire, I believe they are either the antannae or the old radio. They are bundled with the wiring going to the AC controller so I question that. Vacuum to heater diaphragm on right side of engine compartment works but wonder if the diaphragm is shot? looks original...could that do anything?
Thanks
Cadillac Bob

Phil Weber

The sensor unit on the rear of the left hand head is for the metal temp warning light on the dash.

There is also an almost identical sensor on the front of the right hand head which is described in the manual as " Heater Turn-On Switch ".

Might be worth checking

Phil

76 cadillac bob

HI all
I got into the AC today and got the heat and cold working correctly, the temperature wheel works as it should the control module was stuck but works like a charm now I wiggled and did a squirt of dry lubricant  I have hot below for heat cold above and bilevel works great along with the defrost. Only issue is blower only runs high, no low ac unless it is really low, not sure as I cannot feel it. Vacuum is terrific. The baffle/bellows on passengers side is a mystery. It opens when cold air comes in and only closes when I remove vacuum line, not sure what it is for. All else appears to be working well. Hoses are all in great shape, no cracks or deterioration, luckily it was a Pacific NW car so no drying of rubber in desert heat.
Got any ideas on Blower speed?