I have a 1987 Oldsmobile Delta 88 Royal Brougham with the electronic/digital HVAC controls:


The air conditioner doesn't work and the system has been emptied. For the two weeks a year it would be nice to have in my location it isn't worth fixing.

However I need to have a working heater. The air comming out of the vents isn't very powerful. I can hear the fan going full tilt and all the fan speed settings seem to work, but it still doesn't blow very hard. The car was sitting for six years before I got it and I found these on the floor (little foam bits that seem to be in place in other parts of the ducts for sealing two pieces together):


So I'm thinking that there is a leak in the ducting somewhere behind the dash. When the system is set for defog, all the air comes out the defog vent as it should. When set to vent all the air comes out the vents, and when set to heat it is split between the floor and the defog vents. I'm unsure if that is correct for the last setting. Even though it isn't powerful it works for what I need it to do, but I am getting some complaints from my girlfriend. Does this sound like the culprit?

When the car is cold (not just the engine temp, but the whole car) on winter mornings the heater controls have trouble. Sometimes the temperature setting display shows random characters, sometimes it doesn't work at all. During this time none of the buttons work. Eventually the system comes back to life and either resets to the last setting or turns itself off and displays "24". At this point the buttons start to work again. This only happens when it is near or below freezing. I can only guess that there is a bad connection or component in the controls that looses contact when it is cold and makes contact again once warm. When I have time I will take the unit apart and reflow all the solder connections. Has anybody else heard of this?

Finally the heater core developed a leak a week and a half ago. I purchased a new one and new hoses for the entire cooling system. I got all the new parts installed on Saturday. Once all the new parts were installed. I tested it for leaks and put the car back together. To get the heater core out from under the dash I had to remove a bracket with some relays and a white box with two electrical connections. And a black box with electrical and vacuum connections that was mounted to the heater core cover. I didn't disconnect any of the vacuum connections but I did remove all the electrical connections. The black box also had a lever on the top with a round metal linkage connected to another lever on the other side of the heater core housing. This was carfully removed when I took it apart and everything was put back just as I found it.

However now the temperature control doesn't work. I found this out Sunday when driving on the highway. It doesn't matter what I have the temperature set to it comes out full hot all the time. Right now it isn't a bit issue as it is winter and I generally have it set to full hot anyway, but when it starts to warm up again I will like to turn it down. All the controls for vent/defog/heat work as they did before. Can anyone suggest what I might have broken/not put back together right? Is that linkage what controls the mixing of hot and fresh air?

Any help and suggestions would be appreciated.

Cheers,
Kevin

Sounds to me like you need a new HVAC control head. Rock Auto has one for $92. The part number is 1226566.

Yes that looks like it will solve the "not working when cold" problem. I'm leaning towards using some of my next paycheck on that now.

Still think I stuffed something up when I replaced the heater core. Do you know if that actuator and flap valve (the linkage I described above) is the control for the temperature mixing?

Does this system have feedback? Meaning is there a temperature sensor somewhere in the car that tells it when it has reached the temperature I've set it to?

Thank you for the help!

Cheers,
Kevin

That box you removed with the vacuum lines and electrical connections sounds like the HVAC manifold that responds to signals from the HVAC control head to open and close various components of the heating system. I would start there.

Here are a couple of threads that might help. If the vacuum/electrical thingy you described is what I think it is, you should see a picture of it in the second thread.


https://www.gmforum.com/mechanical-1...8-93-a-285427/

https://www.gmforum.com/mechanical-1...2000-a-279092/

Wow, great info!

I did try searching, but without knowing that the box I was talking about is the programmer I didn't get very far...

I don't think the diagnostic mode would work on mine (no ext temp button, but mines an 87 and thats for an 88 to 93, so there might be another button to press, I will search).

I will take a look next I have a chance, probably next Monday.

Thanks again for the help!

Cheers,
Kevin

Yeah, I'm sure a lot of the information I pointed you to won't apply to your model year, but from your description the basic components are the same and I wanted to give you an idea on what the various components do. Essentially, all the flapper doors that control temperature and air flow are vacuum controlled by the programmer. The programmer is electrically controlled by the HVAC control head. I think you need a new control head ($92 on rockauto.com) but I also think something is broken or messed up with the programmer.

With it being -25 today I went to rockauto to buy that climate control panel. I guess I was too late, they no longer have it listed. I will keep an eye out at the local wreckers and I will probably take mine apart to check all the solder joins.

Cheers,
Kevin

Well isn't that strange. You are correct, it was listed yesterday and not there today. Call the service desk at rock auto and see if they can help you out. You might be surprised.

Do a google on the part number I provided.

I googled the number and it didn't come up with any Oldsmobile parts. The part showed up in the catalogue again and I tried to order it again and ended up being told that it was no longer available and had been removed from my cart. I called the service number and was simply told that they no longer have it in stock. So I signed up to be notified when it is in stock. I will try calling some local shops and find out how much they want for it.

I haven't had a chance to look at the temperature control side of things yet. I am still hoping to have a look on Monday night.

Thanks again for the help and I will post updates as they happen.

Cheers,
Kevin

The black box with the vacuum lines and arm on the top is called the A/C Programmer.

Yes the rod on the top controls the hot air mixing door.

Yes I think you need a new control head in the dash.

The foam bits on the floor are from the door inside the dash that controls the air for the defroster and vents. If you ever have a dash apart you'll see how they cover the flapper doors with the foam so that they seal, but after 20 years the foam breaks down and disintegrates. It is nothing to worry about and would be an absolute nightmare to repair. Mine is the same way.

I have a used one of those control heads I'd be delighted to part with for a fraction of $92. I drove the car it came from so I know it is a good unit.