Had a call on an old Carrier RTU about 2 weeks ago, don't know the model # its about 5 ton, built about 1983. Problem was a welded contactor, no big deal, changed it out all checked out. I installed a 30 amp contactor compressor running around 15 amps RLA. Didn't think much about it, this week I get a call, find the contactor I installed totally trashed, the bar and spring between the points laying in the bottom of the panel and points melted to the point of nothing left. The other pole was fine (2 pole contactor), this time I installed a 40 amp square D, mega ohm compressor, its good, power is clean (least while I was there). Thermostat is a digital Honeywell that has a time delay, so I know noone is jamming it off and on. 24 volts coming back on Y1 and 24v @ coil. It does has A CLO card that works, economizer is bypassed because owner does not want to spend the money to fix it, so we know the economizer has no control over compressor, for what its worth..Suggestions please ?