weird #$!* and hot rods

Why does weird stuff happen to hot rods?

I have a hot rod air unit on the 32. I got it all in but the heat does not work and I assume there is something with the vacum switch. I have not removed the dash yet because it is a hassle.

Here is where the weird #$!* comes in, both heater hoses appear to be sweating OIL. Both lines are oily outside in the engine compartment and inside the cab (which eliminates engine oil) and besides the A/C lines are dry.

Any thoughts out there???????

Some vacuum operated flow switches won't operate if installed backwards.