______________________________________________________________________ I have a Carrier 4 ton condensing unit that tripped my 50A circuit breaker. The unit was working fine for 9 years. After some troubleshooting, I discovered that the contactor in the condensing unit had some charred areas where there was obviously some electrical arcing/shorting was going on. I am going to replace this part tomorrow morning and it will hopefully be the cause of the problem. My question is, how common is a contactor failure and, when a contactor fails, is charring a usual indicator. Could this be a sign of something else?? The capacitor looked fine and I didn’t see anything wrong with the compressor or quick disconnect wiring. Thanks for the replies. Replies: dperk001 “Re(1):Contactor failure question” , posted Mon 11 Jul 09:51 ______________________________________________________________________ It is probably not going to be your problem a pitted contactor normally does not trip a breaker unless it start stops the compressor in a rappid succession. Contactor failure is common normally it fuses the contactor points together causing the unit to contiously run or contact points will not make contact causeing the unit not to run. If your unit runs, check your start up amp draw and run load amps on the condensing unit if it is in range from the Condensing unit data plate, More probable cause to your problem is 1. you could have a motor problem either the Compressor or the Condensing fan motor failing even though the outside wiring looks ok the windings inside can either be overloading and grounding out. 2. circiut breaker may be getting weak and tripping thekubiaks “Re(2):Contactor failure question” , posted Mon 11 Jul 10:25 ______________________________________________________________________ dperk001, Thanks for the reply, I think you hit the nail on the head. My contactor on the condensing unit was fused and the capacitor was bloated. I replaced both of them this morning but no success, the circuit breaker immediately tripped when I tried to re-engage it. I am 100% positive the problem is in the condensing unit, there aren’t any shorted wires. So, it sounds like whatever has failed is not something I can replace myself?? Are you saying that you think it might be the compressor motor itself that has seized?? Thanks again for the help. TechMaster “Re(1):Contactor failure question” , posted Sun 10 Jul 21:00 ______________________________________________________________________ It is a very common part to fail. Contacts get pitted and burnt. As long as the wiring and capacitor look good, you should be good. Just make sure there aren’t any shorts or grounds. Keep Cool! bubbad “Re(2):Contactor failure question” , posted Mon 11 Jul 21:49 ______________________________________________________________________ If the breaker is tripping, you do have a short. Usually it’s the compressor motor itself, the wiring leading to it, or a bad crankcase heater, (if you have one). bubbad thekubiaks “Re(3):Contactor failure question” , posted Wed 13 Jul 03:54 ______________________________________________________________________ bubbad, You were right, it was the compressor itself that failed and took out the capacitor and contactor. Thanks for the help.