Hi all! Looked thru the threads and could not really find an answer to my issue.

Bought a home this winter which has a heat pump. Heat and Aux Heat work fine but now I get no Cooling.
I have a Carrier indoor unit and Payne outdoor unit. Noticed that the 5amp fuse blown in circuit board on indoor unit after switching to cool setting on TSTAT. Replaced it, blown again..

After the second time this fuse blown I noticed the transformer is now Tango Uniform..(Dead!) Replaced this. Now I am back to where I was before.. no cooling.
I isolated the indoor unit from the outdoor and set the TSTAT on Heat for a period of time.. Everything works good.
So I put a DMM to the C, Y, O lines at the outdoor unit.. bingo all three are shorted together.

I am looking at a schematic and here is the routing..
(inputs)
O---------------->Reversing Valve<----------C
Y----->LPS<--->DTS<--->HPS<--->CONT<---C (Comon path)
C-------------------------------------------C
LPS=low pressure switch
DTS=discharge temp switch
HPS=high pressure switch
CONT=contactor

This Payne outdoor unit is a PH10JA030000 and is no more than 3 years old. I was going to troubleshoot this last night but thunderstorm came thru and rained me out..

I am leaning towards a bad or fused contactor.. I would assume that the C and O would be shorted if the reversing valve is closed..
If anyone has some insight or has come across this before it would be greatly appreciated.. Trying to get as much info as possible before going home tonight.

Thanks Again,
Alpine

 

well i found the problem..
one of the wires going to the reversing valve had rubbed the insulation off and grounded the wire to the copper line.
I find it amazing that these units are not dressed correctly when installed. I had to pull, splice and ziptie a bunch of wires away from potential shorting hazards.
Well problem fixed and now I am in the cool.