I'm a jack-of-all-trades. My contactor got stuck in the on position (it was pitted and kind of burned). I replaced it with a new one, but stupidly connected the Low Voltage wire to the same side on the contactor. Some wires smoked at the contactor and I shut off the power.

The neighbor (studied for A/C but not working in the field) showed me my error and correctly hooked the LV wire. Afterwards, the 240/24 volt transformer had no power coming out the 24v side. We replaced the transformer and it burned out again. 240 Volts come to it, but 24v don't come out.

I can't visually find a shorted wire from the 240 side back to the blower motor nor at the blower's capacitor. The blower seems to run fine according to the neighbor. There is no circuit board. Another A/C friend told me, over the phone, that it could be the blower motor having a short.

This forum's previous postings suggests a short along the 24V wiring (through thermostat and/or contactor).

Before I call repair man, should I replace the 24V wiring and contactor? Should I replace the blower motor? Thanks to all suggestions, in advance.

Quote:

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Originally Posted by jsemelgar

I'm a jack-of-all-trades. My contactor got stuck in the on position (it was pitted and kind of burned). I replaced it with a new one, but stupidly connected the Low Voltage wire to the same side on the contactor. Some wires smoked at the contactor and I shut off the power.

The neighbor (studied for A/C but not working in the field) showed me my error and correctly hooked the LV wire. Afterwards, the the 240/24 volt transformer had no power coming out the 24v side. We replaced the transformer and it burned out again. 240 Volts come to it, but 24v don't come out.

I can't visually find a shorted wire from the 240 side back to the blower motor nor at the blower's capacitor. The blower seems to run fine according to the neighbor. There is no circuit board. Another A/C friend told me, over the phone, that it could be the blower motor having a short.

This forum's previous postings suggests a short along the 24V wiring (through thermostat and/or contactor).

Before I call repair man, should I replace the 24V wiring and contactor? Should I replace the blower motor? Thanks to all suggestions, in advance.

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You will need to disconnect all low voltage wires from each circuit and test each cable or bundle for shorts and continunity.

To stop the transformer from burning out after you test all the wires and decide to replace the transformer again I sugges you install a fuse in the low voltage circuit. Attached is a drawing that shower the circuit to fuse. In the drawing it showes a miniature circuit breaker but you will probably never find on and that is why you need to install a fuse holder and fuse where the circuit breaker is. NOTE Ignore all other wiring on drawing except the transformer to the R low voltage circuit.

NOTE make sure you are using a transformer designed for the power supplied to it. In your case 240 volts primary as stated in your post.

My Solution:
The contactor was burned out (perhaps shorted) at the wound coil. This was causing the transformer to burnout. I bought a new transformer with a reset switch and a new contactor.

I want to VERY MUCH thank HVAC1000 for his assistance.

Glad you got it going.