Blend door? Recirculate a/c inside air vacuum?

[J-Dub]

Factory air all rebuilt and blower works and a/c works and newly tested. but seems to be drawing arizona outside air (it doesn't keep getting cooler as you drive) I suspect i can prop open the blend door (or close it?)
**This may help troubleshot: I do seem to have a vaccuum issue in that my blower won't stay blowing through my vents unless I pinch off a vacuum line that goes to a round rubbervalve thing on upper left, which moves a lever). lines and the rubber thing are solid and newer looking.
ANY IDEAS or where can I find the blend door? Thanks!!!

 

[toolmanmike]

What year and model? The early systems might not have a re circulation feature. If it isn't on the controls it doesn't do it. You need some outside air to keep the evaporator from freezing. (and to keep you from passing out)

 

[Jlcaptain24]

What year and model? The early systems might not have a re circulation feature. If it isn't on the controls it doesn't do it. You need some outside air to keep the evaporator from freezing. (and to keep you from passing out)

Mike,
Aftermarket AC systems are Recirc only....I'm currently putting a Classic Air system in my dart. Are the old systems different somehow? Just curious.
Regards,
Jason

 

[toolmanmike]

Ahhhhh Classic Air. I didn't read far enough I see. I wonder if a vac hose is connected to a wrong port. Might have to give Classic a call. They've probably run into the problem before.

 

[J-Dub]

It's 73 scamp, and my original users manual says the "max ac" should use inside air (maybe the normal AC does too?). There is no change in my system from "max ac" to "ac". So I'm suspecting now the control module (switches) itself. ? I did notice the lower left side has a vacuum that keeps defrost vents open or closes them, and that isn't closing the defrost vents, so maybe I'll try pulling/clamping the defrost control so they're closed. ?hmmm

 

[J-Dub]

Ahhhhh Classic Air. I didn't read far enough I see. I wonder if a vac hose is connected to a wrong port. Might have to give Classic a call. They've probably run into the problem before.

Oh The system is original ac and blower I assume is also.? the controller looks original

 

[toolmanmike]

It's 73 scamp, and my original users manual says the "max ac" should use inside air (maybe the normal AC does too?). There is no change in my system from "max ac" to "ac". So I'm suspecting now the control module (switches) itself. ? I did notice the lower left side has a vacuum that keeps defrost vents open or closes them, and that isn't closing the defrost vents, so maybe I'll try pulling/clamping the defrost control so they're closed. ?hmmm

A factory service manual might help. Here's a link to free manuals online. I don't see a 73 Plymouth manual but a 72 may work. There is a 73 chassis and body manual listed for Dodge. The controls might be the same. MyMopar - Mopar Forums & Information - Service Manuals

 

[Rustedwrench]

Factory air all rebuilt and blower works and a/c works and newly tested. but seems to be drawing arizona outside air (it doesn't keep getting cooler as you drive) I suspect i can prop open the blend door (or close it?)
**This may help troubleshot: I do seem to have a vaccuum issue in that my blower won't stay blowing through my vents unless I pinch off a vacuum line that goes to a round rubbervalve thing on upper left, which moves a lever). lines and the rubber thing are solid and newer looking.
ANY IDEAS or where can I find the blend door? Thanks!!!

I do not know specifically about your car but many older cars with vacuum operated servos would default to defrost mode if there was a insufficient amount of vacuum or a vacuum leak. I would disconnect the vacuum line in the engine compartment that supplies vacuum to the heat-a/c control. Disconnect it from the engine and connect a vacuum pump and see if it will hold vacuum. If not, pinch off vacuum lines under the dash one at a time until you find the leak. Easier to start there before tearing things apart.

 

[Jlcaptain24]

Ahhhhh Classic Air. I didn't read far enough I see. I wonder if a vac hose is connected to a wrong port. Might have to give Classic a call. They've probably run into the problem before.

Mike, I'm not the Original poster with the problem...was just trying to educate myself. I was just curious. I basically run my truck on Recur all summer and don't have any issues. Regards, Jason

 

[RedFish]

Majority of vacuum servos have 1 supply tube for 1 movement and internal spring return. A very few servos have 2 supplys for 2 movements and no internal spring. Your description suggests one of these 2 tube servos is hooked up backward. Just guessing. Easy enough to test.