75 Lemans Automatic Temperature Control (only blows hot air)

[75LemansGT]

Hi everyone my 75 Lemans has an automatic temperature control for the climate. It’s operated by vacuum and all of the vent controls work correctly, opening and closing the different actuators to allow air to flow in the intended directions.

The problem I have is the temperature control slider (cable) doesn’t make any changes to the position of the temp door (blend door). This door bypasses the air flow from blower around the heater core at various levels to achieve the correct climate temp. Mine stays hot all the time. The vacuum actuator that moves the blend door arm gets vacuum all the time causing the door to always flow air through the heater core. Unless I disconnect that white vacuum line.

The black vacuum line goes to the vacuum checking relay and splits into two ports. The service manual calls the device a “programmer”. It has two actuators that have two white vacuum lines from the checking relay. Port one goes to the programmer vac motor located on the bottom of the programmer assembly. Port two goes to the compensator vacuum regulator.

The temp cable is correctly adjusted as per the service manual instructions. It’s just that when it is moved from full hot to full cold and anywhere between, the vacuum actuator that moves the blend door does nothing but hold full vacuum. So hard to find any info on this. I’ll attach pics of the “programmer” from both sides.

 

[melsg5]

Does the manual show vacuum flow in the different positions and does it show a vent to release vacuum?

 

[75LemansGT]

The diagram shows the black vacuum line the feeds the checking relay actually T’s off twice and gets direct vacuum from the engine. Shouldn’t the temp slider be able to adjust the position of the blend door regardless of which setting the climate control vent option is set to?

The programmer has two flexible hoses that connect to the upper left and middle right of my first picture. The upper left goes to a small vent above the glove box on top of the dash. I assume this is used to sample the air temp inside the car to adjust the blend door position and or a/c (which isn’t working right now, compressor is leaking just going to replace the whole system with an original air kit). The other hose goes to the firewall near the blower motor to draw air through the programmer.

Can I post a screenshot of the manual?