1 year old A/C condensor not turning on

Hi,

I have a 1 year old Tempstar AC/Heat unit. Heater works fine.

Only when I turn on AC, the fan and compressor outside don't go on.

AC technician stopped by and replaced capacitor and fuses. And said that AC breaker is only reading 94 volt, once I replace it, AC will work.

I replaced the breaker. Now there is 134 volt power to AC unit.

Still same thing, when I turn on AC, the fan and compressor outside doesn't go on.

I already called AC technician to come out again, but it won't be for few days. Any suggestions, I want to have second opinion before AC technician is out here.

Thanks,

Paul

 

You can push the contactor button(use an insulated stick) to see if that turn it on. The contactor is that small black box right next to the capacitor (see the second photo). there is a small button in the middle of it (see through the yellow curved wire location in the photo)

 

I pressed the button down at contactor. Nothing happens with AC fan or compressor.

Thanks,

Paul

 

I just found out the everytime I press the contact button, AC breaker(50amp) trips.

This is why my AC is not coming out.

I have already replaced the breaker.

Is there anything else can caused AC breaker(50amp) to trip.

Thanks,

Paul

 

The two most common causes for your symptoms are a wire has rubbed against a copper pipe in the unit and created a short, or the compressor has shorted to ground internally.

 

It's possible that you have a shorted compressor winding, or the winding is shorted to ground. You would have to turn off the power to the outdoor unit, and disconnect the wires where they connect to the compressor (usually 3 wires). You should wear protective eyewear before removing the compressor wires, as the compressor is under pressure, and there's always a chance that the pressure could release while working on it.

With the wires disconnected from the compressor, measure the resistance between each of the terminals. Assuming 3 terminals (1, 2, 3), you would measure resistance between 1-2, 2-3, 1-3. The resistance is typically something similar to what's shown below.

Pin 1 to Pin 2 – 3 ohms
Pin 2 to Pin 3 – 6 ohms
Pin 1 to Pin 3 – 9 ohms

Also, check resistance from all the compressor terminals to the chassis (ground) on a high ohms scale. You should measure infinite resistance (should measure as an open circuit).

 

If you don't have a meter or don't want to measure the ohms as suggested, you can try to disconnect compressor, then push the button, and connect it back but disconnect the fan then push the button. By doing this simple test, you should be able to find out which one is shorted. (but be careful, 240V down there !)

 

It maybe best not to try the disconnect and repower method of troubleshooting or that contactor may explode.

 

Well, up to him, but I have never had a contactor explode on me.

 

If you feel comfortable working inside the unit,with the power OFF remove the 2 wires from the contractor that go to the compressor,restore the power and with someone inside have them turn the thermostat for a call for cooling and see what happens.

 

The 2 wires on the contactor are Run and Common. There will be a third wire feeding Start. It is the blue wire on the C terminal of the run capacitor.

 

Busy with Mother's day weekend.

Thank you for these information, but I don't have any help so I will leave your suggestions for AC technician which will come out for free the second time.

Thank you again and will update you the result.

Paul