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1969 Mark III AC Control Questions

Hello Bill -

I have a great Lincoln Mark III from 1969 but I have a problem with the AC control.
It will not regulate, I have studied almost everything.

Power servo is working as it should according to the manual also the AC box.

I have found the following:

1) water valve will not close,must be close in OFF state.Valve OK
2) Recirculation does not open in High.Valve OK

But I have found something there is No minus at terminal 14 yellow wire red connector in the AC Box. On the diagram I send you. Can you tell me where I find "ENGINE THERM. SWITCH" as shown in the diagram on on the Car.

I am interested in buying a El diagram of the vehicle.

Yours sincerely

Steen in Denmark


Greetings Steen -

To answer your various questions, we have found that the manual is incorrect regarding the water valve operation. This valve will be normally be open in the OFF position ( no vacuum ). If the engine was turned off however with the ac in the full cooling mode in High position it may receive vacuum and remain closed for a period of time.

The recirc. door vacuum motor will only receive vacuum in the High position and when the system has driven to the FULL cooling mode. When the system begins to modulate from the full cooling mode as the interior becomes cooler, the recirc. door motor will be vented and the door will open to fresh air.

The engine coolant thermal switch on the 1969 Marks is located on a clip that is attached to the rubber water pump bypass hose. That yellow wire will be grounded by that switch only when the coolant temperature is cold as in a cold engine. That circuit is part of the cold engine blower delay feature that operates in the High and Low switch setting and when the system is operating in the heat mode only. On later Marks ( 1970 and later ) this switch is located integral with the engine temperature gauge switch.