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Discussion Starter #1
Hey everyone,
I'm having an issue with 94 Fleetwood. I can't get the cabin temp to change. No heat, no cold air. The heater core lines get good and hot after the car is running, and the a/c lines get ice cold. I dropped the bottom off the heater box, and the heater core is burning hot, and the a/c condenser is ice cold. I checkied the codes and nothing comes up. I have checked all the vacuum lines and they all seem good, no leaks. Does anyone know where I can find the mixer control on the heater box? I'm thinking it may be stuck? Any ideas?
 

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Is there air blowing? Did you check the vacuum motor that works the temp door? You need an FSM to do the checks.
 

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Discussion Starter #3
Lots of air blowing, and I have also changed the vacuum control under the glove box, and still nothing. I read that sometimes the system needs to recalibrate it's self, and it's as simple as pulling a fuse, so I did that, and it went through all the steps, and still nothing. the cabin temp doesn't change much from the outside temp.
 

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Assuming you get correct vacuum to the manifold, the only possibilities are; the door is stuck, the vacuum motor is not working, the linkage is broken, or it is not getting a signal from the HVAC module to the vacuum manifold.
 

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Are you getting any vacuum to the control? Check that. If not, check the vacuum check valve under the hood. I had one that was intermittently screwing up on a '95 Brougham that I had. It would cause exactly what you're describing.
 

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Discussion Starter #6
Thanks! Where is the vacuum check valve located, and what does it look like?
 

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Discussion Starter #8
Found the problem!

I found out that the mixer door is controled by an electric motor just behind the glove box. That was my issue. Thanks everyone for you help!
 
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