mkhargrove

I'm guessing that the hose connected to the block is the hose that should be downstream from the heater control valve (assuming the diaphragm piece that I'm holding is part of what was once a complete heater control valve). So all I need to do to actually have a functional air conditioner (mine is cold when I start the car after it hasn't been driven for a while, but blows air that is not so cold after a few minutes) is disconnect the hose from the block, connect a short piece of 3/4 inch heater hose, and connect a heater control valve between them?

FredR

Rule No1 of posting- tell us what model year you have [and whether it is left or righth hand drive]. Obviously yours is an earlier model with a 16V engine.

The stock heater valve is a plastic, vacuum actuated device controlled from the HVAC system. Assuming the early model valves are the same as the later model items they have an integrated actuator just like the one in your hand on the photo.

The heater valve is positioned on the passenger side [left hand drive models] of the block and connected via a short piece of rubber tube [a specific Porsche part number] and then via a hose back into the system via the heater core. The valve requires "vacuum on" to close the valve and thus the default position has the valve wide open - the position it takes when the engine shuts down and vacuum is off. The vacuum is taken from the vacuum reservoir which is a passive system that derives vacuum via the little check valve located on the nipple of the brake servo.

mkhargrove

This is an '84 928S

From what I have read, it seems that all models use the same valve and have very similar layouts for the hoses and valves from the block to heater core connection.
I've also read enough threads to be convinced that there are a lot of valves with flimsy doors that collapse and allow water to flow through even when they're supposedly in the proper closed position. I intended to check the door of my heater control valve, but when removed the air filter, the above picture is what I found.

My first question is this...shouldn't the hose that I've called out have a heater valve inserted a few inches away from the connection to the engine? And, my second question....the vacuum actuator that I'm holding...is there any other device in that general area that it should be attached too, assuming it's not "half" of the missing heater control valve?

AirtekHVAC