: 1988 Brougham Climate Control Problem



PurtyVille '92
07-09-09, 03:20 PM
If there is a previous thread on this, I apologize as I am unable to find it with the search.

I just purchased a 1988 Brougham with 54K original miles. This is my second Cadillac, but my first RWD. Everything on it is great, but the Climate Control is not functioning correctly.

Sometimes, the buttons on the ECC will allow me to select them, and other times, they will not change. This makes me think there is an issue with the ECC computer.

When it does work, I can change the temperature, but air does not come out of the vents on the dash. However, the two vents directly under the ECC will exhaust some air (I say exhaust because it doesn't really blow). The temperature of this air DOES change with the corresponding selection on the ECC.

Also, the "Outside Temp" will display -45 degrees almost all the time.

Is there a way to hard reset the ECC computer? If not, do any of you wise gentlemen (and ladies) have any suggestions as to what to try first?

Thanks!

sven914
07-09-09, 07:03 PM
The diagnostic trouble shooting trees in my 89 factory manual lead to the replacement of the ECC head or the programmer, for most of your issues. The air coming out of the floor vents is not electrical, but vacuum related. There is a black vacuum canister (looks like a ball) mounted on the passenger's side fire wall of the engine compartment; check to see if there is a good vacuum source to it.

For your obvious electrical problems (not being able to use the ECC or having -45 displayed all times) I would try to have the problem diagnosed before I threw a new ECC head or programmer at it. With the service information and a 12volt test light, the ECC is easy to trouble shoot. I recommend to any Cadillac owner, that they acquire the OEM factory service manual; there a few on eBay for an 88 Brougham (http://shop.ebay.com/items/?_nkw=1988+Cadillac+brougham+%5DService+manual&_sacat=0&_trksid=m270&_dmpt=Motors_Manuals_Literature&_odkw=1988+Cadillac+Service+manual&_osacat=0).

PurtyVille '92
07-10-09, 10:11 PM
Thanks. Sorry for the bump but I can't send private messages since I am noob.

carnut
07-10-09, 10:18 PM
I agree with SVEN 914. Most likely a faulty circuit board in the dash ECC control head. But should be diagnosed first. As you know the dash vents will only blow cooler air never warm, depending on what temp you set and what in car temp is. My 84 was doing that erratically and it was the ECC control head. Got one from a pick n pull yard to see if the problem changed and in fact that used part fixed it.

PurtyVille '92
07-13-09, 06:31 PM
If I set the desired temperature to 60 degrees, does it always come out of the dash vents?

Or, since it more than likely needs to be charged, the air that comes out is hot, so it goes to the floor vents instead?

Basically, is the air flow determined by the number displayed on the ECC, or is it determined by the actual air temperature?

sven914
07-13-09, 07:40 PM
Where the air flow comes out is determined by the temperature sensors, both outside and inside the vehicle. If the inside temperature of the vehicle is less than what is set on the ECC, then warm air will blow from the heater vent on the floor. If the in-car temperature is greater what is set on the ECC, cold air will blow from the dash vents. The ECC uses engine vacuum to change the direction of the air. So where the air comes from has nothing to do with it's incoming temperature.

sditmer
01-27-11, 08:45 PM
I've been dealing with my '87 Brougham RWD heating A/C issue as well. My issue stemmed from a fan that wouldn't come on, but the blower functioned in the direct-grounding test. My problem was trying to determine if the issue was the power module on the fan housing or the programmer. I did the performance steps but still no success. The ECC seemed ok as all the lights and digital readout were working fine. I was speaking with a mechanic-friend of mine who said in reference to the power module on the fan housing, "I've replaced countless numbers of these, and only a small few programmers. Have you rapped on it yet?" I laughed, but he said "try it." So I did, and darned if the fan didn't start working again! But, in trying to trouble-shoot the programmer, I messed up the vacuum lines on the INSIDE. I wrote done the colors but lost my paper. Does ANYONE have info on the vacuum lines inside the programmer? Also, one of those lines had a small metal pin blocking airflow in it that could not have come through any of the nipple orifices. Is it supposed to be in there?

Thanks to anyone who can help.

JimMLINY
01-31-11, 04:57 PM
Had same problem when I picked up my 88. It had sat for 3 years. A can of CRC QD Electronic Cleaning Quick Drying Formula sprayed into each button then pushing the button numerous times cleared up the contacts and it functions well since. Have to spray sometimes when some buttons are unresponsvice but it is a cheap fix.

C-Leb
12-08-12, 06:49 PM
im having a similar problem and would love help.
I have an 88 brougham and the fan works great, heat is good but the colder it gets (outside)the harder of a time i have of getting the fan to turn on. Sometimes if i change the temp to 60 I can get the fan to turn on and then switch it back up to 90. But if its really cold, like today -19 then even at 60 the blower motor wont turn on....
I have a spare climate module from the junkyard and that never sorted it out when I swapped it. I found out there is some sort of crazy complex blower resistor but its $400!!!
Havnt been able to find one of those at the junkyard yet.
Anyones help or advise would be greatly appreciated.

carnut
12-08-12, 10:25 PM
It's called a power module. It sets in the underhood housing on the drivers side of the fan motor. It controls the varible fan speeds as well as initally turning on the fan. Was used for many years on Eldo's, Seville's and rear wheel drive Cads. from about 82 thru your 88. You might try pressing the windshield defrost button rather than moving the set temperature to confrm fan operation. The defrost position by passes the varible fan speed, goes to max fan when pressed. Dont know where you live but these modules are common here in wrecking yards for about 25 to 75 dollars.

C-Leb
12-09-12, 05:44 AM
that what i thought the problem was...
sort of a fancy blower motor resistor for old skool climate control.
I found that napa makes one for 450$$!!!!
Man I really hope the junkers score an old caddy this week its minus 20 today :(

C-Leb
12-30-12, 12:19 PM
still in need of help guys!!
I managed to find a power module in a junkyard, had it shipped here. Still having the same problem....
So Ive changed the controller and the power module.
Like I said before when its warmer around 0(32) or hotter if i switch it to 60 the fan will kick on and then i ramp it up to 90.
But today its -17(-5) outside and it wont work at all until ive driven maybe for 20 mins.
It seems like there is something wrong with the bypass, even on defrost the motor will not turn on. Maybe something wrong with the byass circuit, can anyone tell me how the bypass works... Is it related to some sort of ac switch that might not be working right...

Really really would appreciate the help as its sooo cold!!! and I have not heat :P

sven914
12-31-12, 02:50 AM
Is the temperature still reading -45? If it is, then there could be an issue in either the temperature sensor or the ECC head unit.

I recently had an issue with mine, where the blower would randomly stop working; somedays it would never come on, despite any button I pressed. I ended up replacing the power-module, but that didn't really fix the issue. It turned out that the ground strap on the blower motor had come loose, and even though everything in the system was working, I wasn't getting any air.

The blower motor screws are threaded into the fiberglass of the air-box, and they can strip very easily. Any of the mounting nuts (around the edge of the blower motor) can be used to re secure the ground wire. On mine, the mounting bolts wouldn't tighten down enough to make a good ground connection, so I ended up using one of the small holes drilled into the blower motor housing; it doesn't need to thread into the fiberglass, but it needs to screw down tightly to the metal blower motor housing.

C-Leb
01-31-13, 11:24 AM
ok so im still having this problem sigh....
checked my ground wire and all mounting bolts and everything is fine.
Can jump the ground and fire up the motor anytime, still something in the system. Im going to try and find another ECC unit and another power module hoping that maybe the replacement ones i have are bad aswell since they are junkyard parts...
My question cani use an ECC control unit from any year caddy...? i figured as long as they look the same it shouldn't be a problem any help would be greatly appreciated as it was -27 yesterday brrrrrrrrrrrr

cadillac kevin
01-31-13, 05:08 PM
ok so im still having this problem sigh....
checked my ground wire and all mounting bolts and everything is fine.
Can jump the ground and fire up the motor anytime, still something in the system. Im going to try and find another ECC unit and another power module hoping that maybe the replacement ones i have are bad aswell since they are junkyard parts...
My question cani use an ECC control unit from any year caddy...? i figured as long as they look the same it shouldn't be a problem any help would be greatly appreciated as it was -27 yesterday brrrrrrrrrrrr

As long as it looks exactly the same as yours (the early 80s had a different button layout), it should work. I don't recall if ones from eldorados/ sevilles will work (fitment wise) though. But ones from say, 86-89 brougham will work for sure.
Have you checked your blower resistor pack? They seem to be a common source of annoyment on older GM vehicles.
I'll check my FSM when I get home and see if I can figure out anything else for you.

Edit: just thought of something for your outside temp reading. Is your outside temp sensor still intact? Is it unplugged?
It is located in the top center area behind the grille and bolts to the header panel right above the grille. IIRC, you get to it by removing the plastic piece between the header panel and radiator support.

carnut
01-31-13, 05:37 PM
If you ground the blower motor, does the system then control the blower speed? If you ground it and low and hi positions change its speed, I would think you have a power module problem underhood. The rear wheel drive Cads used a different module in the dash than the Eldo's and Seville's. Same wiring plug, same functions but it wont attach to the air box. Have you replaced one of the blower motor flange screws with a nut and bolt and made sure no paint is between the bolt and blower motor. If grounding the blower motor turns it on then it has to be a poor ground wire connection to it, I would think.

C-Leb
01-31-13, 07:03 PM
As long as it looks exactly the same as yours (the early 80s had a different button layout), it should work. I don't recall if ones from eldorados/ sevilles will work (fitment wise) though. But ones from say, 86-89 brougham will work for sure.
Have you checked your blower resistor pack? They seem to be a common source of annoyment on older GM vehicles.
I'll check my FSM when I get home and see if I can figure out anything else for you.

Edit: just thought of something for your outside temp reading. Is your outside temp sensor still intact? Is it unplugged?
It is located in the top center area behind the grille and bolts to the header panel right above the grille. IIRC, you get to it by removing the plastic piece between the header panel and radiator support.

if im not mistaken the ac power module under the hood is the equivalent of a resistor pack in the brougham I did get one from another 88 in a junkyard but nothing changed...
If there is some other component im unaware of plz let me know.

My outside temp sensor is plugged in and works great it read -02 last night (Fahrenheit) cold night not to have any heat :(

----------


If you ground the blower motor, does the system then control the blower speed? If you ground it and low and hi positions change its speed, I would think you have a power module problem underhood. The rear wheel drive Cads used a different module in the dash than the Eldo's and Seville's. Same wiring plug, same functions but it wont attach to the air box. Have you replaced one of the blower motor flange screws with a nut and bolt and made sure no paint is between the bolt and blower motor. If grounding the blower motor turns it on then it has to be a poor ground wire connection to it, I would think.

I have not replaced one of the screws but i never have the motor cut out once working. As I said in previous posts its only when its very cold outside that it wont work. Even when warmer i can only get the fan to come on by turning the temp down to 60, after the fan kicks in then i turn it backup to 90.
Ive read about a feature that prevents the motor from running until the car is warmed up, going to defrost bypasses this but not on my car....
Anyone know more about how this circuit works? I thought I might have a problem there unless its all controlled via the ECC unit...



Sorry my problem was similar to the original post ive hijacked it, i never had my ecc reading -45 outside temp. Mine has always read properly

The Ape Man
01-31-13, 09:22 PM
Maybe there's a block temperature switch to lock out heat function while the engine is cold. Dunno for sure on an 88. After 85 I did not really work on these lines.

If you call for defrost or set to 60 and the blower runs but won't work on cold days look for a block temp switch for HVAC. Those beasties were a problem on all older Cadillacs.

carnut
01-31-13, 11:31 PM
I just looked at www.rockautoparts.com cataloge. Its shows a 5 pin relay for the A/C fan. A $6.00 part. worth a shot! DELCO part numbers, D1746C or 19106975.

C-Leb
02-01-13, 12:40 PM
103207

I found this and im going to go through the steps today, hopefully its not to warm.
Only thing that confuses me is they talk about 2 separate parts, the programmer and the control head...?
I thought there was just one the ecc module in the dash...

carnut
02-01-13, 03:51 PM
Programmer, behind glove box. Control head, center of dash to set the climate mode you want. Power module under hood next to the fan motor itselfthat changes the fan speeds. Just dont go to either extreme on the temp display. stay below 90 and above 60. Both max temps will raise the fan to max speed. You not only want the fan to work, but you also want it to modulate the temperature automatically based on interior temp.

The Ape Man
02-01-13, 04:52 PM
Great you have the service notes!

I'd try reseating the connectors on the control head, programmer and power module. They may have a loose connection. Just a shot in the dark but a cheap one.

coodeville
02-21-14, 01:07 AM
The price of a power module is now 235 bucks. A lot better than the 400 it was five years ago.

cadillac_al
02-21-14, 09:12 AM
I wonder if the blower motor is just worn out and only comes on when it gets a full 12 volts, either by jumping it or setting the control head to 60.

FWIW my old Seville had the blower control bypassed with a push button when I bought it. I assume somebody did this when they were cold and tired of troubleshooting. I have never fixed it in 18 years and still use the push button when I need some blower. This may be a good temporary fix to get you through the cold weather anyway.

C-Leb
02-24-14, 07:43 PM
Blower motor replaced.
Like I said before it only wont work when its -30 out, so very hard to troubleshoot and COLD!
We had a couple cold snaps in the last few weeks and a few times it didn't work. Went through the troubleshooting tree and eliminated the module, the motor and wiring under the hood. Took the kick panel off and it started working.....
Im inclined to agree with The ape man, I think one or more of the pins at my programmer is loose and when it gets mega cold they contract and don't maintain good contact. The next ffew times I started it and the motor wouldn't kick on if I wiggled that harness it would kick on everytime. So I went through all the pins on the connector bending them as such so they would stay in contact with the programmer better. Everything seems fine now! YAY!!! but we haven't had a bad cold snap since then....
I REALLY REALLY REALLY hope this is finally fixed, ive had enough after 2 cold winters!!