tripping fuse

[chickenwing]

I have a multi stage heat pump with auxiliary heat, it’s a Carrier system. There is a low voltage (5amp) fuse in the air handler that blows out instantly when I turn it to either cool or heat but does fine when just the blower on. Of course when the fuse is out I have no power at all to the entire system. Is this related to my compressor? Does it have anything to do with the Freon level? I've checked all the connections in and around the thermostat and air handler but I'm totally confused on what my next step should be... any info would be greatly appreciated.

[bosstriton]

hi chickenwing,when you turn on the fan in air handler it uses a differant circuit from t-stat,seem to me that the problem is in the outdoor unit,because when you turn on heat&cool,its more than likely
uses the yellow wire for both,i have also seen the wires rubbing next to copper lines in units,causing shorts in yellow wire.i would turn power off to outdoor unit and air handler,if it is a carrier look for small wires rubbing next to copper line in outdoor unit[look close at all wires in lower section,or it could be a shorted contactor coil,because thats what closes each time the unit comes on heating or cooling.

hope this helps

[pertmm]

Even though this post is 4 years old.... Bosstriton's advice worked for us! We have a Bryant heat pump, and it kept blowing the 5 amp fuse. We even called an authorized Bryant dealer, who replaced the fuse, reprogrammed the thermostat, and charged us $75. When the fuse blew the next morning, he came out and replaced one of the circuit panels. The fuse was okay for about a week, and then it blew again.

Living in Tampa Florida without AC is punishment in itself. Frustrated with the AC repairman, I found this forum, and Bosstriton's hints. I took the fan off of the outdoor unit and found the culprit- a red wire rubbing against a copper pipe. I figure that the repairman may have moved the wire when he was working on the unit, but within the week, it settled back onto the pipe and started tripping the fuse again.

Thanks again for the tip!

[HayZee518]

the 5 amp fuse is for the control circuit. most remote condenser units use a 24 volt control circuit - relays for the motors included and motor contactors while the line side can be 240 or 480 depending on where they're used [ home, industrial]