12 degrees and my heater blows cold

[Yorkshire]

I looked at the sticky posted by Gadget and in the trouble shooting section he said the blend door actuator, a gold can behind the glove box, was the likely culprit. So I pulled the glove box on my 91 GMQ only to find no gold can. Can anyone help? The freezing cold, 20 minute drive to work is absolutely terrible.

[VicCrownVic]

90+ are different, what he has in that sticky is mainly intended for the older style 89- cars, but much of it still applies to the 90+.
Do you have manual or ATC controls? ATC will have an auto setting on the fan control on the left side of the control head.

My heat on my 91 has gone back to nearly nothing again, my issue is a clogged heater core/crap in the cooling system. I flushed it back in Oct-Nov sometime and it was toasty hot for a couple weeks. Your issue may or may not be the same thing.

The blend door actuator if ATC is electric and mounted on the heater box. The same box that the heater core is mounted in. It's just as much work to get to the BDA on the 90+ as it is to replace the heater core. Check the two hoses going to the heater core, if one is hot and the other is not, (or in my case both get hot ), then the heater core is likely clogged. If that's the case flush the heater core (I use a garden hose).

[Yorkshire]

Yeah mine is ATC. Another bit of info, last winter the floor option stopped working. Floor = off, not a big deal, i dealt with it. Then summer comes along and i hit a huge pot hole and it would only blow semi cool air put the defrost vents. Then this winter floor = off still but if i would go to the vent or AC option i would hear a fairly loud clicking noise inside the dash. Eventually that goes away and it works alright. But when i go back to heat i hear that sound again and its all cold air. I would fiddle with the controls amd the heat would eventually kick on. Would that clicking be the blend door or something?

Sent from my N9810 using Tapatalk

[VicCrownVic]

Mine is also ATC.
Clicking could be the blend door or the mode door. Depending on the sound it may be the door swinging fully open or closed but I can't say for sure.

The Floor not working is covered in the sticky, iirc. There's an inline temp sensor in the hose going to the heater core, unplug it and jumper the wires and you should have floor option again. I had to do this on mine, I jumpered the connector a while ago and it's still that way even tough I have the replacement sensor. I've just been too lazy to put the new one in.

Also, because my heater core is mostly clogged (you know, like "mostly dead" ) it will heat up if I leave the heat/blower motor off then turn the heat on after driving for a while. Without the blower motor blowing air through the heater core fins I guess the heat has time to transfer from the small unclogged section into the rest of the core. But because the core is mostly clogged the warm air that comes out after doing this doesn't last very long, but it does tell me that the blend door is not the problem. (which I also know because the heat works great for a few weeks every time I flush the core)

[sly]

blend door actuator is probably the issue... PITA to get at, gotta take the whole f'n dash out to pull the stupid thing.

[Yorkshire]

Is there some sort of write up on pulling the actuator? Also while I'm in there would it be worth it to replace the heater core?

[BuffaloRider]

I did my heater core for the first time last summer, it sucked. If it still has the original heater core and you're already taking the dash apart then I would replace it, what do they go for like 30 or 40 bucks? Beats the hassle of doing it all again.


This IS the blend door actuator in question, correct? Kind of to the upper right when looking through the glove compartment.

[gadget73]

just before you get too far into it, is the coolant full and is the system making pressure? If there is air in the system the heat usually sucks.

[sly]

+1 check coolant level

[VicCrownVic]

I did my heater core for the first time last summer, it sucked. If it still has the original heater core and you're already taking the dash apart then I would replace it, what do they go for like 30 or 40 bucks? Beats the hassle of doing it all again.

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This IS the blend door actuator in question, correct? Kind of to the upper right when looking through the glove compartment.

The BDA on ATC (his and mine) when looking through the glove box would be to the upper left. I believe what you have there looks like a vacuum actuator for the recirculation door. Pic from my shop manual points out where the BDA is located:


The last post (#7) in my RR thread has a couple pics of the BDA, but I didn't get a pic of it installed.