[berr3555]

Yesterday I came home and found that my indoor unit burn the transformer. I installed a replacement but the A/C wouldn't work. After a few minutes I noticed a burn smell coming from the unit, I immediately unplug the unit. Today I went ahead and tested the transformer with everything off. It was giving around 26 volts. I went ahead and fused the secondary side with a 1.5 amp fuse. When turning on the fan alone it works fine. When positioning the thermostat in heat or cool, I blew up the fuse right away. I took off the fuse and repeated the process using the door switch so I could get the power off in a hurry, I get a small buzz sound from the transformer and the voltage reading drops to around 8 to 9 volts. At the same time the transformer starts getting hot. I check the outside unit (heat pump) contactor winding and is not open. Any suggestion will be appreciated. I also bougth a new transformer but not using it since the first one tested good without major load on it.

 

[hvactech126]

most likely it is the contactor or chewed through and shorted to ground wire

 

[berr3555]

I went ahead and crawl all over the attic and the wiring is fine. I took to the outside unit and exchange my contactor and it is finally working:thumbup:. hvactech126, thank you for your expert advice.

 

[Ducthunter]

So why did the fuse blow when he was using heat if the short was in the y circuit?

 

[hvactech126]

most likely because it is a HP instead of ac

 

[Ducthunter]

most likely because it is a HP instead of ac

If it's dual fuel I guess the xe 80 is a 80% gas furnace, single stage I think

 

[berr3555]

The contactor

I forgot to update, the problem was the main contactor in the heat pump had a short in the winding side.