Re: replacing push-button motor

Posted by BH On 2011/10/16 10:04:17

Randy had previously mentioned this incident to me, privately. From what I gather, the motor over-travelled, first, and the lock-up resulted in excessive current draw; because the breaker kept resetting, the relay eventually had a meltdown.

I like the idea of a self-resetting breaker for transient events, but if excessive current draw is what cause the meltdown, then perhaps some sort of thermal fuse should be used, in addition to the OE circuit breaker.

GM used a three-terminal thermal limiter on their on AC systems back in the 1970s that would disable the compressor clutch if refrigerant ran low to prevent burning up the compressor. A heat-sensing switch on the back of the compressor switch provided current to a heater inside of the limiter to blow an integral thermal fuse, but it was a one-shot device. This was prior to the advent of pressure-sensing switches.