Climate control problems? Read This!

[sly]

The pisser about using a cable conversion is that connecting by the usual means will make the temp slider reversed as the cable would need to mount on the firewall side of the blend door arm to pull it the correct way on an ATC car. If one were so inclined to make an adapter rod that clipped to the current one to make it look more like a Y, then you could clip the cable to the "adapter" side of the Y and the pivot would be correct for manual control. As far as I've seen, the vent control part of the system is the same. The fan switch is also different, but that can be used manually anyhow.

[gadget73]

the manual control cars pull from the firewall side? Bah. Kind of a shame the EATC is so non-80s looking. It does honestly function better with the electric blend door setup but I don't see any practical way of using that with sliders short of a DIY brainbox in between the two in order to translate the temperature slider into blend door servo signals.

[sly]

the manual control cars pull from the firewall side? Bah. Kind of a shame the EATC is so non-80s looking. It does honestly function better with the electric blend door setup but I don't see any practical way of using that with sliders short of a DIY brainbox in between the two in order to translate the temperature slider into blend door servo signals.

nah... the manual control cars have a different lever on the blend door and pull from the cabin side. The lever on the blend door is 180 degrees out from the ATC vacuum pulled version to accommodate this.

Granted, I'm working on 6 year old memories, so I could have it backwards and it's a direct fit just fixing the cable from the ATC sensor to the blend door... but I don't think it is.

[Brown_Muscle]

If you used that cable setup, could you just swap the lever and cable, or you'd need the whole assembly from a non-ATC car?

[gadget73]

the lever is part of the blend door, so you'd really need the whole piece from a non-atc car to use the standard cable. Or clamp something to the existing door and make it so the cable can be connected to the opposite side it currently can, assuming the manual cars are opposite the auto ones. Its basically 1/8 or 3/16 rod, you could pick something up at the hardware store and bend it to shape. Use a couple of small cable clamps to connect the pieces together. Its not exactly a high stress area.

access is of course the problem.

[sly]

I know that the cable pushes for cold on the manual setup. The vacuum actuator pulls for cold on the ATC setup... so just mounting the cable in place of the actuator would reverse the temp slider. This is why you need the manual plenum and cable or to make a counter lever for the ATC blend door lever (the Y setup I was talking about - more of a Football (American, not futbol) goal post). I think the ATC cable could be used by just dropping it down, but without the counter lever, you'd have to remember to go full hot for cold air and full cold for hot air. I do know the cable fits over the rod as I tried it with my 88 for giggles when I had the dash open for the ATC sensor replacement.

[Not_your_grandpas_marquis]

So, I've read all 8 pages and nothing matches my situation. My heat is hot, A/C is cold, it blows but both heat and A/C blow on the floor and defrost but no vents. Seems my car doesn't have the "coffee can" or "soup can" since it's a 1990 MGM. Can't complain since everything except for vents work but would be nice after working in the sun haha. Any help or advice is appreciated.

[87gtVIC]

I don;t know what your issue is but starting in 1990 the coffee can was replaced by that black plastic rectangular looking reservoir on the drivers side inner fender with the integrated relay holder.

[Kodachrome Wolf]

Sounds like a vacuum leak to me. I'd probably start by checking the actual slider controls at the dash. There's a series of vacuum lines that meet up on the back. If those start to crack or pull out of their block, you won't get air sent to the right spots.

[gadget73]

It may be a problem with one of the air doors in the plenum if the air isn't moving around with the gas or shifting temperature. Starting in 90 or 91, the auto climate control went to an electric actuator so the temperature will not shift with a vac leak on those. This guide was more written for 80s stuff since thats what I happen to own. Honestly though, the climate control system in these cars changed very little through all years of production. Other than going from a vacuum motor to an electric motor on the blend door, the rest of it is all very much the same. The vacuum reservoir changed from a metal can to a plastic tank too, but thats a good thing, plastic doesn't rust.


Pull open the glovebox and see if you can watch the vacuum motors operate. If you can't see it, pull the radio and look through that hole. Depending on specifics you've got two or three back there. Non-auto have two, a floor/defrost and a dash/defrost door. The ATC ones have three, floor/defrost/ dash/defrost/ and the bi-level one which lets some air come out the defrost and the floor at the same time. You may have a disconnected or stuck dash/defrost air door motor, or the air doors in the plenum might be broken and not shifting air. Usually air sort of comes out of everyplace when that happens though.

[kellen302]

How does the ATC sensor unplug from the vacuum harness? I have a donor sensor from the junk yard that I just cut the hoses on, but how does it actually disconnect? There is a white collar around the hoses that I have tried pushing or pulling and that doesn't seem to release anything.

[gadget73]

i want to say there is a small plastic tab that you have to push to get it to unplug.

[sly]

That clip is very stubborn.

[gadget73]

and the rubber connector thing likes to become one with the sensor. Might have to stick a pick in there to help get it apart.

[over2tonsofFun]

My 90 MGM with ATC will blow hot only when it is running above 40+ mph. So, should be a vacuum leak? I will have to look into it when I get a chance. May unplug the line to the actuator for the wife to get heat.

Tim