Hello all...

I recently dreamed up a way to add thermal control to a window air
conditioner that I'd picked up off the curb some time back. It worked,
outside of the fact that whenver the thermostat was connected, the fan motor
would eventually grind down to a halt. It made no sense to me, seeing as the
compressor is the only thing switched by the thermostat. So I did the quick
and dirty thing, and I bypassed it so the compressor is running whenever the
unit is on.

My first means of control was a heavy duty timer that could turn the unit on
for a while and then turn it off. This was cumbersome at best, especially as
the timer had no way to "know" when it was too cold for A/C.

So I got a programmable thermostat, a 24 volt AC transformer and a heavy
duty contactor with a 24 volt coil. This setup works great to cycle power to
an outlet placed especially for the air conditioner, and the parts were all
freebies. But I've noticed that the coil on the contactor gets hot, and I'm
wondering if this is normal. I've looked around for wiring diagrams and even
looked inside some furnaces like the one where the the parts came from to
see if I'd need a current limiting resistor or something. But I don't see
anything like that in use. It looks just like the wiring comes from the
transformer, with one end going to the contactor and the other going through
the thermostat.

Am I going to ruin the coil, or do they just run hot when energized?

William