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1977 Mark V Hissing Noise

Hi Bill,

For a few months I´m the owner of a 1977 Mark V 400 cui. When I got the car, the temperature control didn´t work because the heater core was not attached to the cooling system. AC doesn´t work anyway. The tan hose to the servo motor (blend door) made a hissing sound and was not attached. So I plugged it with a screw. Since it´s getting colder now, I attached the heater core and the tan hose to the servo motor. Surprisingly the temperature automatic works like it should, though the hissing can still be heard. IMO it comes from the servo motor, but could it then work perfectly? The hissing is rather bugging.

One more question. How can I remove the right hand instrument panel applique for better access to the vacuum motors?

Best regards from Germany



Hello Ewe -

To answer your question can the Climate Control work perfectly when you are hearing a hissing sound. Yes, it can if the Climate Control is still receiving the necessary amount of vacuum that it needs to operate. I suspect however that you have more unnoticed problems than you are describing. Hissing sounds can only be located with a shop manual, patience and a good ear. If you want to diagnose and do the repairs properly in a logical manner to your recently purchased Mark V, having and reading a factory Shop Manual will do wonders for you now and in the future.

If you wish to remove the wood grain panel above the glove box for any reason you only need to look under the instrument panel cove and locate the easily visible phillips screws. Have you looked there for any attaching screws yet? Removing these screws should allow tilting or rotating the panel from the top towards the interior and then removing it. We wish you good luck with your Mark.