1993 sedan deville, climate control

Climate control and fuel data center go blank. At this point the blower fan comes on ,but it is only cold air, I have no control of buttons, they do not respond. Problem is intermediate. service engine and emmissions also come on. There is voltage at all this points.

service engine and emmissions also come on

That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code (like P0123) not just their translation into English and post it back here.

Regarding warning lights:

  1. if the coolant temp light comes on, shut off the engine ASAP

  2. if the oil warning light comes on, shut off the engine ASAP

  3. if a FLASHING MIL/CEL comes on, shut off the engine ASAP

    ASAP means driving to the berm of the highway right now and not waiting for the next exit.

But if the MIL/CEL is not flashing, then it’s not an urgent indicator.

Your computer could be out to lunch. If so, you would need a new one because it’s not coming back. I may not be correct but only the computer influences all these things at once. I had a similar, darn near identical problem on an 85 Cadillac (apples and oranges) but I changed it and it was cured. I had separate controls for the heater, or to be accurate, my heater control for heat output was always fluctuating but I lived where I hardly needed heat.

GM side terminal battery=potential electrical problems
To ensure that you’re getting full power to all circuits, remove the battery terminals and clean. Pay particular attention to the positive connector, under the rubber cover. There should be two ring terminals, and corrosion often builds up between them, causing flaky electrical system operation.

I don’t see why the CEL light would turn on when the climate control has a problem unless there is a common power lead to them and there is intermittent trouble with it. Have you checked the power to the climate control system when the trouble is occurring?

There is voltage on the tan wire .5 volts, orange and black 16 volts. The car runs fine just no heat. Checked relays all good. someone suggested body control module, not sure what it looks like, it is suppose to be behind glovebox. There are two metal boxes one large ECM? one small BCM?