[zgtal]

works well when cooling
when switched to heat makes a short circuit
opened the switch and disconnected the wire from the switch to the thermostat switch, works but only cooling.

what can be the problem?

[PS Staff - Sheila]

It sounds like the thermostat is bad.

[zgtal]

check the thermostat, no short circuit

[huxley]

Hi,

I think there is some fault in the thermostat that s' why it is not working properly. You try to check it to the expert technician why it works improperly? He would suggest you better way what should be done with the shorcircuit of air conditioner.

[gwr]

more input please? is it a gas furnace or electric ? what switch are you refering to

[SINCE1972]

If it is electric one of the coils is broken and shorted to the case.
Better get a pro to fix it.
since 1972
burke

[Philtac]

1) possible low voltage short between the common wire and the heat wire.
2) possible low voltage short in your heat relay or stack switch.
3) possible low voltage short in the thermostat circuit to heat.
4) possible low voltage short in the heat wire to ground.
5) possible rats chewed through your t-stst wire in the attic.
Shorts are hard to diagnose, without a meter, isolation and process of elimination.