I have a Goodman Heat Pump. The transformer in the air handler burnt out and I replaced it with one protected with a reset button. Now, when I use unit, I can only use in emergency heat. When I use in heat or cool mode it will trip the transformer in 30 seconds. Is this a low voltage problem? Air handler is in basement and is just a short distance from outside unit and easy to replace low voltage wiring to outside. Would this correct problem or should I look for another problem? The low voltage wiring visually looks fine. What else should I be checking? Thanks for any help.

If you have a ohm meter you should check the resistance on the 24 volt contactor coil. If you don't have a meter, pull one wire off the coil and try to start the unit. If the transformer doesn't trip the overload you have a bad coil. Usually a shorted wire will trip the overload instantly. You could also have a defective circuit board or a bad coil on the reversing valve. Some Goodman units also have separate time delay relays that short out.