carrier heat pump

[miller-cold-filtered]

hello everyone,

today i'm stuck on a carrier heat pump and i can not reolve the problem. its a package 5 ton carrier 3 phase unit. running as cool when thermostat set to heat. it seems to stuck on defrost when there is frost ( check def thermostat, close, low voltage present). revers valve has continuity, but the funny thing is that after the disc turned back on the reverse valve has low voltage right away. then about 30 sec, comp kick on, blow kick on, reverse valve not energize.
heat relay ok
circuit relay ok
contactor ok
pc board ok
by-pass ther w/ G + O + R( thermostat ok)

anything that i over look?

[frigetater]

"anything that i over look?"


yes

[jrbenny]

You have the thermostat configured for heat pump. Carrier commercial package heat pumps require a gas/electric thermostat configuration.

Look at the low voltage terminal board. There's no O terminal there.

[thermal bum]

Did ya find the problem yet? Whats the M# and how old is it. I've found that honeywells new touchscreen 8000 stats do not like old carrier heatpumps. Backfeeds like crazy