: It's HOT in Texas, and I have a HOT '89 Brougham d'Elegance



My_favorite_Brougham
08-18-10, 05:38 PM
Literally. My A/C is being intermittent, and leaving me sticky and sweaty.

For some reason, my A/C compressor clutch will only engage 5 minutes after starting the car. Then it runs fine. In fact, the A/C blows very cold and keeps me chilly even 108-degree Texas weather. Why is this? :suspense:

I have to start the car 5 minutes before I go anywhere, and that gets pretty annoying, and the rest of the family doesn't want to go anywhere in it because of it. If we stop anywhere, it starts all over again: another 5 minutes of heat and sweat before the clutch kicks in.

I checked the clutch itself, and it's fine. I put 12v up to the switch, and it and it engages as it should. And the system is fully charged. So why then is my clutch taking forever to engage? I feel like wiring my own engage/disengage switch under the dash, but I really don't want to.

Any ideas? The low refrigerant switch on the compressor appears to be fine, but I don't know.

-Greg :crybaby:

csbuckn
08-18-10, 07:39 PM
Unfortunately, that is the correct way. It waits until the air is cool before it blows. The only thing that work immediately in AC mode is defrost.

sven914
08-18-10, 09:12 PM
^That's why, when mine is pissing me off and baking or freezing me to death, I confuse it. Hit defrost, then AUTO, anytime you want on-demand air flow or A/C.

My_favorite_Brougham
08-19-10, 02:10 AM
Really?? I had a '90 and '92 Brougham, and neither did that. Also my '83 Oldsmobile never did that (manual switches, but still, it never needed to cool down first).

I wish my Brougham were like new cars that blew cold instantly. Oh well, I guess that's the R4 compressor and under-sized condenser for ya.

But still, my fan will blow hot air on Hi. How can the air "cool down" for 5 minutes if the compressor isn't even turning? It just blows hot air for a while, and then it instantly blows cold air. I want to know why it doesn't just blow the cold air instantly.

MudAnt
08-19-10, 03:21 AM
But still, my fan will blow hot air on Hi. How can the air "cool down" for 5 minutes if the compressor isn't even turning? It just blows hot air for a while, and then it instantly blows cold air. I want to know why it doesn't just blow the cold air instantly.

Actually, if you put the system on ECON/fan only, the air coming out cools down after a few minutes. The reason it blows hot at first is because the ducts are hot from the sun.

The ducts would cool down a lot faster if the compressor was running, but perhaps they put this delay so ice cold air doesn't blow through the baking hot ducts, causing rapid contraction, which would eventually crack the plastic.

My_favorite_Brougham
08-19-10, 03:52 AM
Somehow I still think I have a problem. It is very unpleasant to be dripping sweat in your eyes from your brow after just a minute in the car. It's like an oven. I can't see an automaker, especially Cadillac, allowing that.

Here's another reason I think why. All Broughams have a feature to disengage the compressor under wide-open-throttle. Well, I can be driving the for a while - and be all comfy chilly - but when I floor it it kills the compressor and doesn't re-engage for another 5 minutes of driving. Under the "cool down" period theory, the system would already be cooled down and not need another 5 minutes.

And believe me, it takes a whole lot less time to re-heat than to cool down in Texas heat. After 20 minutes of cooling the interior down, it can all be lost and hot again in 1 minute.

MudAnt
08-19-10, 04:57 AM
That is true. Also further disproving my own theory, I've noticed my compressor comes on before the fan even spins up when I start the car.

csbuckn
08-19-10, 02:52 PM
The service manual says there is a delay but it doesn't say how long. Five minutes seems like a long time. Maybe a relay going bad?

sven914
08-19-10, 04:38 PM
Upon further thought... There shouldn't be any delay of the compressor engaging. What csbuckn was probably thinking of, is the delay in the blower turning on, when the temperature set on the ECC is greater than the temperature inside or outside the vehicle (indicating heat is desired so the blower is held off until the engine warms up).

I've also had some, unresolved, problems with the compressor clutch not engaging for up to an hour of driving (after the main course of ball soup, there was pleasant dessert of frosted cubes). It's only happened a few times, so I just ignore it, like the washer/wiper problems, fuel leak, and the check engine light. But, after looking at the wiring diagram, it looks like the A/C Cut-Out Relay could be sticking, or there might be a bad connection between the ECM and the Compressor, via the Brown wire.

tbcaddy18
08-19-10, 04:45 PM
I have the same issue with my A/C clutch engaging and disengaging. Sometimes it engages in the beginning then it will cut out for a while, or sometimes it will continually cut in and out as if there's some kinda of connection issue.

I haven't figured it out yet, but I have cleaned all the visible A/C related connections in the engine bay.

sven914
08-19-10, 04:51 PM
^That's called cycling. The compressor is supposed to periodically engage and disengage while the A/C is on. It does that to conserve fuel while the air conditioner is on without causing periods of under cooling.

tbcaddy18
08-19-10, 07:49 PM
^ but in my case it does cause long periods of under cooling. :ill: however other times it will work just fine. I'm thinking maybe there's a loose ground somewhere?..or could a bad power module unit also cause a intermittent problem similar to this?

sven914
08-19-10, 08:26 PM
I doubt it. It is normal for the compressor to cycle (it would be more of an issue if it didn't) and driving a 24 year old car around southern California can cause under cooling.

A bad power module would be causing problems across the system, and I've never heard of one haveing intermittent failures. As for your loose ground theory, the only grounds in the system are the cycling switch and the low pressure switch.

*I was wrong in my previous post (#9). The brown wire is the ECM signal wire, and doesn't control anything.*

My_favorite_Brougham
08-20-10, 04:09 AM
Hmm.. could it be a control head problem (the dash control box)? I have seen several Buick Roadmasters that have had A/C problems due to electrical issues and a perfectly fine refrigerant system.

Right now it sounds like my easiest option would be a manual clutch engage switch. I could run it parallel to existing wires, so I could kill it after 5 minutes and be normal. Of course, doing this risks my compressor health should I have unexpected low refrigerant levels. I really don't want to do this.

(On an unrelated note, we had this exact issue with my mom's '92 FWD Deville. We had to replace the ECM for another problem and it cured the a/c problem too.)

jayoldschool
08-20-10, 11:59 AM
To properly diagnose your system, you need to get some gauges on it. Harbor freight has a cheap set.

sven914
08-20-10, 08:24 PM
Replacing the ECM might have solved the problem before, because the ECM controls/supplies the ground to the cut-off relay (so it can turn off the compressor when there is high engine load). You can cut the ECM out of the system by taking the relay directly to ground, and it will still work and switch on and off as normal.

The relay is supplied power by the power module when the A/C is set to on, so taking it to grounded won't affect that. The compressor will still cycle correctly because the cycling switch and pressure switch are the clutch's grounds, and remove that ground when open. If it wasn't for the E-carb, the ECM could be completly removed and the car wouldn't function any differently; which is why I'm working on getting rid of the E-carb.

My_favorite_Brougham
08-23-10, 06:07 PM
Well I discovered a clutch problem diagnosis section of my service manual so I will check it out. I do have a set of R12 gages and have seen that I have ample freon. I'm thinking either a control module or a compressor relay. We'll see.

Till then, I have to put up with this until the A/C kicks in!

http://i182.photobucket.com/albums/x141/Shutterbug668/IMG00134-20100802-1554.jpg

And sadly this weather has caused my brand new headliner to begin sagging in the rear.

-Greg

sven914
08-23-10, 06:17 PM
Have you tired turning the temperature to 60 and hitting Defrost. That might trick whatever is malfunctioning into giving you "emergency" compressor engagement. I've found the system to be rather stupid and easy to trick, as you can usually use defrost make it forget the warm-up fan delays. It might work the get your compressor clutch to engage earlier.

My_favorite_Brougham
08-23-10, 06:21 PM
I have. It doesn't make a difference. I have recently begun experiencing disengagement while driving. It will randomly turn off during long drives for 5-10 minute periods. Then other days it will instantly come on at start up.

tbcaddy18
08-24-10, 09:22 PM
^^^ I have the exact same issue too

My_favorite_Brougham
08-22-11, 04:04 PM
Well friends, believe it or not I still have this issue. The good news is I have thoroughly narrowed down the problem using the FSM schematics, and I know for a fact that the problem is the A/C Power Module, also referred to as the A/C Blower Module occasionally.

I was just putting up with the issue last summer, and winter wasn't really a bother - winters are nice in Texas - but now my blower has completely died. It's not the motor, which I've tested; it just won't engage. All signs point to the power control module. It sits immediately right of the blower motor under the hood, and has two heavy wires: a ground, and a wire to the blower motor. There's also a 6-pin plug where it receives info from the dash controls. (This is oddly similar to the radio head unit and amp setup in these years, too.)

My dilemma now is finding one. Rockauto has them for about 10x the salvage yard price, but that's a bit steep for me (yes, even in Texas heat). And I'd like a used one. However, none of the yards around me have RWD Cadillacs anymore! What a shame! I think many have been crushed lately unfortunately, and few yards have cars from before 1990.

That's just a very late update!

Greg

csbuckn
08-22-11, 05:15 PM
What year cars can you get this part from? Winter in Texas? I came home(Fort Hood) for new years and it was like 75 degrees. Long way from Minnesota. My dad says they have been getting hundred plus days pretty much all summer.

RocketFast321
08-23-11, 01:17 AM
Here's another reason I think why. All Broughams have a feature to disengage the compressor under wide-open-throttle. Well, I can be driving the for a while - and be all comfy chilly - but when I floor it it kills the compressor and doesn't re-engage for another 5 minutes of driving. Under the "cool down" period theory, the system would already be cooled down and not need another 5 minutes.


Alot of if not all cars do that. At WOT on both my grand am and alero above like 4k, the PCM kills the a/c. But once i take my foot out of it the a/c turns back on. I would start looking for bad connection, and old wiring. What you have going on is not normal. Their is also a resistor on the compressor plug that could be going out..


^That's called cycling. The compressor is supposed to periodically engage and disengage while the A/C is on. It does that to conserve fuel while the air conditioner is on without causing periods of under cooling.


ummmm nope.
The system builds up pressure on the liquid line. The compressor shuts down when it gets high. The liquid line pressure drops and the compressor kicks back on. Alot of new cars still do this. My car the compressor does not cycle. I forget what those are called. If i remember our old 84 sedan deville right. On auto 60, it would blow air out the feet first them switch to face. Running on HI would default to face. The only delay i know of is the heater delay, i have that on my 84 Electra Wagon and our deville had it.


If it wasn't for the E-carb, the ECM could be completly removed and the car wouldn't function any differently; which is why I'm working on getting rid of the E-carb.

You forgot the CCC disturber. You remove both. Without the CCC carb the disturber will not advance right. Also without the PCM the trans will not lock up 4th gear.

My_favorite_Brougham
08-23-11, 02:17 PM
I'm in College Station right now, so Fort Hood is not that far away. And yes, we've have 100+ days for the last couple months. We topped out at 109 a few days ago! :lildevil:

The A/C power module for an '89 Brougham can be had from '86 to '89 Broughams; basically 307 Broughams that are not 90-92. The 90-92 Broughams have a slightly different harness, and so do the HT4100 Broughams. I'm not sure about '81 and before.

And I have good news. I finally found a power module from a private individual's car lot that I heard of by word of mouth. It all works, even better than before! My fan speed is much better than it ever was. Previously, the "Hi" setting felt like low in any other car, but it blows me away now.

Greg

tbcaddy18
08-30-11, 11:45 PM
I've been having this same exact issue with my FWB since we purchased her back in 2003. Sometimes turns on, sometimes not....during cruise it'll stay on and cool for a long period of time...then it'll just shut off for a few minutes then come back on.

I too was thinking it may be the ac power module....is that the part that's sitting on the top back of the engine compartment to the right of the blower fan motor?...is it also referred to as the blower motor resistor?

Pepboys has them for like $300+....but ive seen them on ebay NOS before for far less..but still pricey...

cadillac kevin
08-30-11, 11:49 PM
^grab one (or a couple) from a junkyard. much cheaper