Heat only works with window open on 1966 SWB

[66DC]

So when I'm at operating temperature and moving, heat won't come out of the floor vents unless I have one of the windows opened slightly. Is this normal? Does it have something to do with lower air pressure sucking the heat out of the exchangers?

Thanks,

DF

[304065]

Is the heat lever pulled all the way to the rear? What is the state of your heater cables and heater boxes?

A common but incorrect "fix" for the SWB cars is to fit heater boxes from a later car. Unfortunately that means the cable is the wrong length and there are all manner of kludges that are deployed to compensate. The heater boxes tend to rust up and freeze in one position or another. I would check that they are all the way closed when the lever is pulled aft, that's a key step in making sure you have adequate volume.

While you are back there, what is the state of the flex hoses between your heat exchangers and the heater boxes? Are they Porsche OE or has somebody tried to fit Imperial- sized orange aircraft hose? Are all the clamps in place?

Next, got any holes in the heat exchangers?

Next, are your paper tubes between the heater ducts next to the fan and the heat exchangers in good shape?

If you're moving at speed with reasonable power setting, there should be plenty of waste heat to warm up the air. The early fan puts out 1390 liters per second. That is about 2880 CFM to you and me. Imagine about a 16" household fan, that's the kind of airflow we're talking about.

Which is not to say it's prodigious airflow-- the stepdown in diameter and nine or ten 90 degree bends really step on the flow. But it should be sufficient to give you the old "blowtorch on the ankle while sitting in a meat locker" kind of feeling.

You aren't thinking of driving your SWB in the SNOW are you? Who would THINK of such a thing. . .

http://forums.pelicanparts.com/porsc...966-911-a.html

[flatsixcrazy]

I remembered reading from somewhere (probably from a Panorama's tech booklet) that by opening your windows, you have effectively creating lower pressure in the cabin. This caused the heat to flow from the exchanger into the cabin more efficiently (like you said).

[PeterM1965]

The airflow is definitely RPM dependent, when I need extra airflow I will shift down a gear and the extra RPMs help. As for reducing the cabin pressure opening one or both of the vent windows definitely helps. It also helps with keeping the windshield clear. I'm still driving my 68 and on cold mornings (low 30s) I get the car warm enough to be comfortable without a jacket, though my ankles are definitely warmer than my nose!