I had a service call to a building with a pneumatic thermostat system for the heat. The call came in because the fuse protecting the compressor motor had blown on several occasions over the last week. When I arrived the fused disconnect was in the off position and when I turned it on the motor would not turn and sounded as if it were seized. I immediately shut it off before the fuse blew. When I then turned it back on the motor started and everything worked fine. I repeated this several more times and again it worked just fine.

I am no expert on motors but my theory was that perhaps the motor had a bad start capacitor. Since the capacitor was only 10 bucks I decided to change it. So far it is working fine, but I'm wondering if anyone with more experience working with motors has any different opinions as to what might be the problem.

Thanks in advance