Chassis heat problems

[Don Bradner]

Until a few days ago, my chassis heat was working fine, now it is dead.

The chassis heat on this coach is a lot simpler than has been described for many
others. No summer/winter valves, no always-on Sporlans, no Webasto or Primus.

The water system consists of a single Sporlan valve and a pump, both actuated by
a slide switch in the cockpit (below the backup monitor controls). The valve
should open and the pump turn on whenever the switch is in the Warm position and
the ignition key is on.

When this is done (engine off in order to hear things), there is a discernible
click at the Sporlan, and the pump starts. After a few seconds, a circuit
breaker can be heard to pop, and it goes off. Maybe ten seconds later the
breaker resets and things run for a few seconds more.

Question: Could this be a stuck Sporlan (pump blowing breaker because of back
pressure)? I've looked through the various documents available and don't see a
good way to test a Sporlan valve.

Don Bradner
90 PT40 "Blue Thunder"
Posting today by satellite from Pea Soup Andersen's, Santa Nella, CA