My air conditioning recently stopped working. There is no power running to the wall switch but the fuses at the power board to the house are fine. The furnace is in a closed area without access so I haven't been able to check the control board without cutting a hole through the plaster wall. Before I do this, does anyone have any ideas?
I've checked all switch connections with a circuit tester just to make sure that there was no power.
Another question, does the mains power run into the control board on the furnace before running to the switch, hence no power?
Thanks in advance for any replies.

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Originally Posted by bunyip

My air conditioning recently stopped working. There is no power running to the wall switch but the fuses at the power board to the house are fine. The furnace is in a closed area without access so I haven't been able to check the control board without cutting a hole through the plaster wall. Before I do this, does anyone have any ideas?
I've checked all switch connections with a circuit tester just to make sure that there was no power.
Another question, does the mains power run into the control board on the furnace before running to the switch, hence no power?
Thanks in advance for any replies.

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have you check the breaker box?

Breaker box was the first thing I checked and everything was fine. The circuits had not been tripped.

The air handler(fan) is usually fed with 1 15 or 20 amp 120 volt circuit, and the outdoor unit is usually fed with a 30,40, or 50 amp 240 volt circuit. You may have 240 volts to the outdoor unit, but if there is a problem with the thermostat or air handler can cause everytning to shut down, since the control voltage is usually contained in the air handler/furnace.

Or the control transformer that provides the 24 volt for the thermostat and all control relays may be bad.

Describe the "wall switch" what is it connected to?

WHo ever installed your unit without access to the control wiring should loose their license, as this is usually access to the burner.

Without the proper knowledge of control wiring, and a mulitmeter, you may need to call in a tech, as there are several other reasons that may be causing your problem.

I've tested all the components on the control board, rechecked and reseated all the connections. The system is now working fine and I've got a technician coming in later this week to do some further testing of parts like the compressor.
Thanks for your help and direction. It's helped make a cold house warm again.