[VAC] furnace

[Jim Dunmyer <jdunmyer@xxxxxxxxxxx>]

 Most of these furnaces have a "sail switch" that proves the actual air
flow before energizing the solenoid valve. If it doesn't work, you'll
get no main flame.

Reasons for non-functioning sail switches include: misadjustment,
binding, low battery voltage (motor runs a bit too slow), or plugged up
air ducts.

Another possibility is the "high temp cutoff" switch. This shuts off the
burner if the box gets too hot from inadaquet air flow, etc. If it gets
cycled too much, it can get weak and fail; I acutally read of one person
finding that their coach's manufacturer (not A/S!) hadn't installed
enough ducts to take the air and heat away quickly enough. Installing
another duct and register cured their problems.

Lastly, the gas solenoid valve could be bad, but they're usually pretty
reliable.

Naturally, you'll have checked all connections to be sure they're secure
and clean.

                                       <<Jim>>