I have an older model Fedders A/C unit in my window. When I turn it on the compressor turns on but no fan. If I give the fan a push the fan starts and stays on for about 30min or so. Then the fan stops blowing. I turn the whole unit off. If I wait a couple of hours then I can turn it back on and it works OK. Execpt I still have to start the fan by hand. What could be wrong? The fan turns freely when I start it (it doesn't feel stiff) so I don't think the motor's bad. Please help!! It's too hot for me!