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Cadillac & LaSalle Club Forums => Technical / Authenticity => Topic started by: seok on February 02, 2023, 01:33:12 PM

Title: 80 Biarritz climate control help
Post by: seok on February 02, 2023, 01:33:12 PM
Hey all,
 Looking for someone that knows the ins and outs to the Climate control system on an 80 Eldo.

  Ive been having an issue  that i cant seem to pin point. its a strange one. if I run the car, and set it to HEAT ( a warmer temp) blower will not work in any speed except DEF. BUT if I drop the temp to COOL it will work as intended, ( cool air from vents) and then move the temp to heat everything works correctly until I shut it all down, then we are back to square one.
 Basically the only way to get the heater to blow is if I first drop it down to A/C temp and then set the temp to a higher (Heat) temp. and everything works normal, all speeds.

-DEF blower always works
-COOL blower always works in all speeds (however clutch does not engage) i did jumper the connector and it engaged.
-HEAT blower will not initially work unless temp is set to cool first and blows out of the dash vents, then set temp to heat, only then will heat blower work on all speeds out of the floor
-doors route air to all proper positions.

Since the blower does actually work in all speeds im thinking the power module is fine. (ive swapped out 2 and same issue) ive replaced a broken motor in the programmer a few yrs ago and blend door works properly now.

I have a FSM and followed the troubleshooting trees and tested harness pins as best I could but theres nothing that specifically targets the issue im having, Anyone here have any deep knowledge of this system that can guide me into some more testing or where to look? I just think its strange that HEAT only blower will not work if initially set to heat, but WILL work if set to AC cool and THEN back to heat.  I like everything working properly on my cars and this one is bugging me to death. I cant accept having to set AC then HEAT just to get it to work. i need it to work properly lol
Title: Re: 80 Biarritz climate control help
Post by: TJ Hopland on February 04, 2023, 12:14:35 AM
There is a temp sensor on the engine that prevents the blower from running in heat modes till there is some temp in the engine.  DEF does bypass that and maybe you are just tricking it after that when you can get it to run.  80 was the first year for digital climate control and it was only on the Eldo's.  I think they made some changes for 81 when it was on most if not all the cars. 

I was going to tell you where the sensor is but then noticed your signature says its a 455 swap so who knows.  If this has had this issue since the swap I'm guessing that the new engine doesn't have the sensor and it never got hooked up.  That sensor was just a Cadillac thing so the 455 didn't likely have one and depending on if the car started out with an Olds or Cadillac motor how easy it would have been to notice or figure it out. 

I just looked at the 80 electrical manual and on the schematic its not clear to me at the moment how the circuit differs between the 3 engine options,  Olds diesel that had no electronics at all, Olds gas which was the CA engine option that had an analog computer, and the DEFI Cad motor.  It looks like it kinda gets tangled up with fast idle solenoid in all 3 cases and the AC clutch.  I read the text because that usually clears things like that up and it only appears to talk about the DEFI and isn't quite making sense,  could just be too late for my brain tonight.

On earlier models this sensor was a single wire that grounded at 120*F which provided a ground path for the blower speed control when the system was in the auto modes that let it operate.  80 in all 3 engine cases looks like its a 2 wire sensor.

Big Cad motors this sensor was on the corner of the head behind the alternator so it was sort of hidden and fairly easy to knock off while working on the alternator.  Olds motors I don't think they had a place for any of these sensors.  I think the metal temp sensor which looks similar was on a special head bolt that had a threaded hole for the sensor.  I'm thinking this sensor may have been on the heater water control valve that stuck out of the intake manifold. Looks like a bolt with terminals on it.

I just took another look at the electrical manual and although they don't talk about it there is a photo that I know is an Olds motor that shows the sensor in question is indeed on the water control valve.  The water control valve threads into the intake on the rear right.  There is no note with the picture that says if it applies to diesel, gas, or DEFI but I know its an Olds, not the cad. 

The climate control is literally the last few pages in this manual so I suspect it was added fairly late in the process, perhaps they didn't originally plan to use the digital system in the 80's so I suspect there could be some missing or incorrect info. 

Wires on the sensor are shown as pink and green, if your car was originally an olds maybe have a look around the right rear of the engine harness to see if you see those hanging out there.  If it was a Cad originally they would have been in the harness going to the alternator which was in front of the right head.   
Title: Re: 80 Biarritz climate control help
Post by: TJ Hopland on February 04, 2023, 11:02:45 AM
I'm looking at this again today to see if it makes more sense and I think I now get it. 

-12v feed (pink) comes from B/U fuse and splits to the sensor and fast idle relay located near the wiper motor.
-green output of the sensor (closed over 120*F) goes to fast idle relay coil, other end of coil is grounded.
-normally closed relay (temp below 120) pink power feed is routed through the contacts to the fast idle solenoid.
-normally open (temp above 120 and coil activated) pink power feed is routed out the blue wire that splits to feed the compressor clutch and the "compressor feed" terminal on the ECC power module othewise known as the blower module. 

The engine variables come in as the diesel is just what is listed above.  If it was a DEFI there is a diode across the clutch coil likey to act as a snubber (absorbs electrical spikes when the coil disengages).  The EFI has an additional (to the fast idle) solenoid called a throttle solenoid.

Lots of connectors and devices involved in getting that signal that could easily get lost in an engine swap especially if it didn't start as an Olds.

it doesn't clearly say it but I think that in AC (or defrost) modes the module gets a signal from the controller to send power to the AC clutch which then kinda back feeds the rest which isn't a great design, perhaps changed in later years?  When not in in AC or DEF mode its depending on that temp switch to send power to the clutch and give that signal to allow the blower to run. 

I have not seen an actual diagram of the power module but my guess is that the controller isn't actually 'monitoring' for that 12v signal, rather that power module itself is just using that 12v signal directly to operate the blower controls.  The activate signal can either come from the controller or that temp circuit.  This could also explain how you are able to trick it, once its been activated it self latches or holds just because its not that smart of a circuit.       

 
Title: Re: 80 Biarritz climate control help
Post by: eldofever58 on February 04, 2023, 01:26:48 PM
I think TJ is spot-on with the temp sensor assessment. Earlier this year I went through all the diagrams for each year of the 79-85 Eldo, documenting the changes.

Unlike later years, the 1980 model still used a switch that grounds out to the engine, and this signal is sent to the AC Programmer. Under the passenger side dash, you can ground out programmer connector cavity Y (light blue wire), and see if blower operation starts. You can make that permanent, if you want.

This same circuit runs through the center bulkhead connector out to the engine bay where it's intended to connect to the heater turn-on switch (closes above 120°F). It's a dark blue wire there, cavity F-X on the upper half of the bulkhead connector.
Title: Re: 80 Biarritz climate control help
Post by: TJ Hopland on February 04, 2023, 02:44:02 PM
Maybe take another look at what you have to see if its different than what I have?  Maybe there was multiple versions of the 80's to further confuse things?

From what my 80 electrical manual says its not a ground like other years. Its showing a 2 wire sensor and that its got a 12v key on feed.  If the switch is closed that 12v is sent to the fast idle relay coil. The relay if activated sends a 12v signal from before the sensor to the blower module and the compressor clutch. Internally this must be routed to allow the blower to run if that power signal is there. But this terminal can also be driven by the 'compressor drive' terminal which also may explain ways things could be tricked.   

I do see a 'blower drive' terminal on the power module and its an orange wire from the programmer with no note on what sort of a signal it is. 

Looking at the diagram again I do see a compressor drive terminal on the blower module and that is fed from 2 gray wires, one to the ecc control module which is the thing in the dash with the buttons and display on it and the other comes from the programmer which is where the servos are that move the doors and such.

Before those 2 gray wires get to the module here is a 'compressor cycling switch' that can break the circuit.  Note says it closes between -1c and +7.5c.    If it is or was a diesel there is also a full throttle disconnect switch that can interrupt the signal. 

There are quite a few things that don't seem to make perfect sense or seem like a good design here.  I suspect it may be that they were trying to use some of the analog stuff still and just make it work then maybe 81 they were able to design the full system to be fully 'digital'?   I don't have an 81 electric manual but I do have the regular FSM, maybe later I will take a peek and see what maybe changed.
Title: Re: 80 Biarritz climate control help
Post by: TJ Hopland on February 04, 2023, 03:14:33 PM
So the questions for the OP now are:

-what engine was originally in the car?
-is there a water control valve with the sensor port on the engine and is the sensor there?
-is there still a fast idle relay on the firewall and what does it hook to?
-where is the compressor clutch wire hooked to?

All this stuff was intermingled so pieces missing from the swap can easily start to explain the blower and clutch issues.   
Title: Re: 80 Biarritz climate control help
Post by: bcroe on February 06, 2023, 12:47:23 PM
Which engine is it?  I would expect the 80
manual to cover it for 368 or diesel, use
79 Eldo docs for a 5.7L gas engine. 
Bruce Roe
Title: Re: 80 Biarritz climate control help
Post by: TJ Hopland on February 06, 2023, 09:44:07 PM
80 still had the 5.7 gas as the CA engine so its covered in the manual.  The electrical manual which is what I have been looking at identifies them as diesel, DEFI (the 368), and EFI (the 5.7 gas).  The only differences I see between the engines is minor things in the AC clutch fast idle circuit which also gets tangled up in the temp sensor in question.

His signature line notes that the 80 as having an Olds 455 swap.  If it was a diesel things would have been fairly straight forward, if it was the EFI a little more wiring to deal with but the important stuff still in the right places.  If it was a DEFI then there would be lots of extra wiring and what you needed to keep was all in the wrong places.     
Title: Re: 80 Biarritz climate control help
Post by: eldofever58 on February 08, 2023, 01:00:37 PM
The nice thing about the '80 Eldo is that the climate control interaction with the engine is exactly the same whether it's diesel, CA-350 or 368 DEFI. Even the climate control head part number is the same. This would change in later years to make use of the serial data stream from the ECU to determine engine temp for warmup, but for now, the CC is independent.

No harm in grounding the blower enable wire as ID'd in my post above as a first step. 5 minutes of your time will tell the tale. The switch might not have gotten installed during the swap, or it may have failed.
Title: Re: 80 Biarritz climate control help
Post by: TJ Hopland on February 08, 2023, 01:56:10 PM
Interesting, now I see that switch/sensor in my book.  I wasn't really looking in that area, I was looking where most of the other under the hood stuff was and found one that also trips at 120f. 

My book not having specific locations for the different engines is hard to tell which they are talking about. The 2 wire sensor that gets tangled into fast idle and AC clutch says LH front of engine. The Cad motors have ports there and in an olds it could be in the intake because there is a coolant crossover in the olds intakes so that statement could apply to both engines.

The heater turn on one they have a picture of and its an Olds in the picture.  It shows the water control valve standing out the intake on the right rear with the sensor pointing out of the top. With the Cad engine I would think they would use the old location, corner of the head behind the alternator.

The people that designed this mess must have been under pressure to get it done and pulled in different directions trying to accommodate different models and engines.

I can also see how who ever did the swap could have easily been confused if it wasn't a diesel. Diesel had a fast idle that was tied to the coolant sensor and not a lot of other wires so it would have been easy to trace that out and more or less figure out what it did. 

If it was DEFI or EFI or even the mid year Buick V6 there are more wires and sensors so I could see them abandoning the coolant sensor that is involved in the fast idle and clutch circuit thinking it was related to ECU stuff so that could be why the AC clutch isn't working correctly. 

For the heater one being a single wire that could have just got lost in the mix especially if the swapper wasn't that familiar with Cadillac and them having that sensor.