Hello, I have a Janitrol model A30-08 furnace. On the AC side, when the thermostat calls for cooling, sometimes the blower kicks on, sometimes not. The evaporator coils always cool down (to the point of icing if I don't intervene), so that part is working fine.

When the blower doesn't come on, sometimes if I smack the outside of the blower housing, it kicks on immediately. Sometimes, simply opening the furnace door (really small closet) kicks it on.

I have read through the other posts, and if I can get my hands on a tester, I will check the voltage on the time-delay relay for 24V on the control side, and line voltage to the blower.

Any ideas? Is this indicative of a bad capacitor, or relay? Or is the blower fan just getting stuck--it does seem dusty back in there. THANKS!

Sounds like a classic case of flaky relay. Unfortunately the newer ones are on a circuit board, making diagnose and replacement tough. A whole new board is $$$$$$$$

Actually, the relay is completely separate, and would be easy to switch out. Would a flaky relay 'come on' by whacking the housing?

Thanks
Doug

Yes, but a lighter whack directly on the relay would be a better indicator. Take it off, take it to an electrical supply, and let them match it up. Relays are fairly cheap.