Hydro Flame Heater won't light when wet

[Desert Tortoise]

Hello List,
I have had my 2000 Eagle for about 6 years.
The Hydro Flame OE furnace has always worked except when wet.
If it's raining, and especially if I've been driving in the rain, the fan will start,
but the furnace will not light.
If at home I have put a small space heater pointed into the furnace vents on the inside.
After heating up the space behind the vent for 10 minutes of so, the furnace will light on it's own.
Ideas, solutions, much appreciated!
Thank you!
Fenton

 

[camelracer]

Could be condensation on the igniter. Can you hear the spark when this happens?

 

[Desert Tortoise]

The usual scenario when wet is there is no spark clicking
Occasionally it will light but stays lit for a few seconds only