My gas dryer had been acting up recently. The clothes would almost dry, but
with a front load washer they are not all that wet anyway. Still, it didn't
seem like the heat was staying on very long.
The other 2 symptoms were these:
1 - On the Timed settings, both heated and air fluff, the timers would
advanced normally. However, on the Auto-Sense settings (high heat or low)
the timer would advance to about halfway through the range on the dial and
then stop. The dryer would then run continuously with no heat, even for
hours at a time, until we manually shut it off.
2 - Regardless of what setting we would use, we always had to wait at least
15 minutes after the dryer shut off before the burner would come on. If we
tried to start the dryer right after the last load, the drum would spin,
the normal click would be heard after about 15 seconds, but the "whoosh" of
the burner coming on wouldn't be heard. If we let the dryer sit for about
15 minutes, we'd get the 15 seconds of spinning and then "click-whoosh" as
the burner came on.
A little research seemed to point to the gas valve solenoids as a possible
cause. If the gas turned off too soon, the clothes wouldn't dry completely
so the Auto-Sensing mode might not trigger the dial to advance. However, in
Timed mode, the timer would advance normally since that setting doesn't
care if the clothes are dry or not. That makes sense.
A local parts store had the solenoid pair for $30, so I swapped them in and
the dryer worked perfectly after that.
Everything seems to make sense except for the 15 minute wait time between
cycles. What in the gas valve solenoid circuitry, or in a solenoid itself,
would cause the dryer to need 15 minutes of rest before the gas would come
back on? In either mode, Timed or Auto-Sense, the dryer had more than
enough time to cool down since the gas turned off soon after the cycle
started. So why did the dryer have to be completely off for 15 minutes
before the gas would turn back on?