Max AC Option on HVAC?

[1975Jimmy]

I've been going nuts trying to figure out why the recirculation door on the passenger side kick panel won't open. I've tried every selection on the AC panel, but nothing. I read that it only opens in Max AC mode, but my 75 doesn't have that option on the HVAC panel. How do you get the door to move? Also, my blower motor seems to work on every setting except for HI - I bought a new blower motor speed switch but haven't installed it yet. Anybody else have this issue with Hi not working?

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Also, can somebody post a picture of what their recirculation door looks like? I had to fabricate a linkage for mine, but am curious what the factory linkage looked like.

 

[BEEBOB]

I had to replace a white plastic tab that connects to the door. got it from the dealer, couple of bucks. I think i bought a extra, i can look and see then shoot you a pic.

 

[blazer74]

Try full cold to the left to activate max mode. My 74 is that way but not sure when the panel changed inside , mine is slightly different. Has a switch at full cold that puts blower on high and opens the recirc. I was thinking 74 75 was the same but not sure after looking at your panel tho.

Maybe the diaphragm is bad at the recirc door also.

There is a single fuse on the pass side firewall off the junction block for the high blower and a relay by the evap box.

 

[1975Jimmy]

Found the issue: there is an inline fuse on the wire in the engine compartment leading to the blower. The fuse was blown. Replaced it and now max ac works

 

[1975Jimmy]

Found the issue: there is an inline fuse on the wire in the engine compartment leading to the blower. The fuse was blown. Replaced it and now max ac works

I noticed something, MAX AC does work, but the air recirculation door doesn't open or close at all. Probably going to need a vacuum diagram to figure it out.

 

[1975Jimmy]

After hours of tearing the dash apart to chase vacuum lines, I finally decided to pull the control unit out of there dash and disconnected it from the control module that has the vacuum lines connected to it. Sprayed some wd40 on the sliders in the module and slid the mode selector slider back and forth to free it up a little bit. Sure enough the mode selector just wasn't sliding far enough to the edge. It would engage the high fan setting (electronic contact) but not send vacuum in MAX AC to actuate the two vacuum actuators (one in the passenger kick panel, other in the cowl). I lubed the vacuum control module with white lithium grease and bent the arms of the AC control panel on the mode selector to make sure it slides the vacuum control module slider even further. Bingo, now I get MAX AC and the recirculation door opens. 40 degrees at the vents on a 100 degree day! I'll take that as a win.

 

[JOES89K5]

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