HVAC damper operation: SOLVED

GOT IT WORKING OK. I THINK THE CONTROL SWITCH THAT DIRECTS THE VACUUM TO THE ACTUATORS NEEDED A LITTLE EXERCISE.

I am rebuilding the HVAC on my 1972 Ambassador and have run into a problem that has really got me scratching my head. It has to do with damper operation versus selector position. This is a long explanation so if you scroll toward the bottom there is a summary and some questions.

There are three vacuum actuated dampers in the system.

One is in the heater box and controls outside air/blend/recirculation.

The second is in the evaporator box and controls air to the windshield for defog or defrost.

The third is also in the evaporator box and controls air to the floor.

The heater box damper actuator has two hoses connected to it. One has a yellow stripe, the other blue. This allows it to control the damper in two positions. At rest (no vacuum applied) it the damper closes off recirculation air (RA) so the system is at 100% outside air (OA). There is an intermediate position to blend OA with RA, and a third position which closes off OA so the system is 100% RA.

Each evaporator box damper actuator has one hose. The defog/defrost damper has a hose with a red stripe going to it. The damper controlling air to the floor has a green stripe.

At rest, the defog/defrost damper is open to the windshield vents and the damper to the floor is closed.

The air flow control lever has 7 positions: Off, Max AC, Norm AC, Heat, Defog, Defrost. The Technical Service Manual (TSM), pages 12B-4 ,5 explains air flow and damper position for most of the selector positions. It really doesn't explain the “VENT” position.

After rebuilding each box (new heating coil, new evaporator, new insulation, new damper seals, I wanted to check out the operation before re-installing on the car. I hooked a vacuum source to the long black hose, connected the rubber manifold to the selector switch and noted actuator/damper position at each position.

The markings on the control connection are YEL, BLU, BLK, RED, BRN, WHT.

The hoses when connected the way I think they should be are YEL, BLU, BLK, XXX(no hose), RED GRN.

I have double checked damper assembly, and based on the pictures I took before disassembly everything appears to be the way it was originally.

SUMMARY

Long story short (a bit late for that now), the actuator/damper operation is opposite from what the TSM says. I tried reversing the rubber manifold connection, but that cut off the vacuum source and really didn't fit right.

This leads me to believe there was a problem at the factory, and all the years I drove the car from new the dampers never worked correctly, although the system heated and cooled the interior, though not as efficiently as possible.

Now my questions:

Has anyone else run into this problem (1972, 1973 Matadors & Ambassadors)?

Was there a TSB issued on possibly an incorrect selector valve or vacuum connections (the actuators are color coded to match the hoses)? This car was an early build (December 1971) and they changed the HVAC on the 1972 models.

I believe I can play around with the connections at the actuators and get the system to work as per the TSM, but would prefer to fix this correctly – if there is such a thing.

Adolph John Rydzewski, Newark, Delaware