David,

Testing for rear heater leaks and having a blower motor that will not
turn on are unrelated.

The on/off valve, located on the rear heater unit itself, just blocks or
opens one of the heater hoses to restrict or allow flow.  In other
words, when the cooling system is up to operating pressure, the heater
hoses and heat exchanger are pressurized regardless of the valve
position.  Pulling the valve actuator toward the front of the van should
allow flow and will cause the heat exchanger to heat up as the engine
coolant heats up .... assuming the PO didn't bypass the heater ...
external to the cabin.

Bring the Van up to operating temperature then gently wiggle the valve
and hoses.  Sometimes the valves leak .... sometimes the O ring where
the valve sits on the heat exchanger leaks ... and sometimes the core
itself might leak.  Oh, I almost forgot to mention .... sometimes none
of 'em leak ..... heheheheh.

Mike
'84 GL 7 pass
'85 GL Westy

Ok... Took apart the rear seat and took a look at the rear heater, have
some
solidified (white powdery stuff) coolant on the fins and around one of
the
hoses but no sign of liquid anywhere... I tried running the heater to
see if
I smelled any coolant or saw any leakage, but the motor will not turn
on...
What's an easy way to test if I have a bad heater or bad switch?

Thanks,
David / NJ
Former owner of a 76 Westy (sniff, miss ya Wanda)
New owner of an 85 Westy Weekender Wolfsberg