warm air in cabin

[Dave Underwood]

Just curious about your warm air on co-pilot's side. How well does your defroster actually work?

What serial number and year is your P337?

I have some issues with mine that are not that different as it involves the same controls.

On a P, the reason the air is warm is it is off the turbo. Look at Figure 88. The air goes through the sonic venturi restrictor on the top of the engine and then through a valve that either sends the air through the heat exchanger for cooling or to the heater. I would look at that valve first. From the heater air then goes through the firewall and flapper valve.

From there it goes to a control valve below the pilot's right foot, Figure 90 Detail C, which directs air to the defrosters or floor vents, including the vent on the P2 side. I can't seem to get as much flow through the defroster as I would like and it would appear the valve which is controlled from the panel slider is reversed.

With the first control valve after the sonic venturi in the right position actually putting air through the heat exchanger, you should get coolish air out. It is shown as item B in figure 89A in the parts manual. Figure 89A shows the best view of all the parts.

I would suggest you have a look at that first valve and then the second one. If you have a source of clean air say from a vacum to blow through the system at the venturi, you shoud be able to sort everything out.

Hope that helps and please let me know what you find.

Regards - Dave