Still working on my a/c issues--

Sat a/c stopped working following a storm.

Opened a/c contact was burned. Replaced contact. Reassembled. No a/c

No power in thermostat lines. Manually push in contact on a/c and it runs fine.

Started looking for the problem in the thermostat lines. Changed batteries in digital honeywell thermostat. No help. Yes it was turned on and the cool was set at 65 outside temp over 80. Turned off then on several times just to be sure.

Looked all through the inside and outside of the furnace for a fuse. No car type fuses. No Fuses in wire lines. No fuses in clips. No fuses on the external furnace shut off switch. Yes it was on.

Switched out thermostats to a mechanical one. No change. Took off the thermostat and twisted the wires together (red/yellow). No change.

Took out and inspected the furnace circuit board- no signs of burned transistors or broken components. Good solders. Clean board.

No power at thermostat wires on board.

Power converter/transformer to 24 volt looked nasty. Replaced it. No change.

Bought a voltage testor.

NO power in the thermostat lines at the A/C. No power in the thermostat lines at the thermostat. No power in the thermostat lines on the furnace circuit board.

110 going into the furnace pcb board. 110 at the connections to the new converter/transformer. Nothing measuring coming out of the old or new converter/transformer.

Could the new unit be bad? If not what next?

Very irritating. Please help

It is possible you got a bad transformer. I would hook the transformer directly to 120 volts and see if it produces 24 volts out. This way you eliminate all the furnace wiring for this test. That will tell you for sure if the transformer is bad.

IF you got a 120/240 volt universal transformer as the replacement make sure you are tapping the correct wires for 120 vbolt use.

The correct wires are?

In side --my choices white/black - pair I used -- 2 not used orange and red
Black is off to one side and the white/red/orange all come out of the same opening.

Out side is blue and yellow

It should be written somewhere, on the box it came in or on the transformer itself which wires to use for 110V or which to use for 220V

Usually white and black are for 120 volt input usage but I would always check the transformer label like wmproop said.

wmproop:

We're trying to educate those in the US that 110/220 V is dead. It's now 240/120. Pass it on.

:) :) :),, OK,I`m from the old school,is hard for an old dog to learn new tricks:) I just have to try harder