Electrical issues with A/C

[jrbryner]

The other day my A/C unit wouldn't turn on. I ran though some troubleshooting: , checked the breakers, tried turning on the heat (also did not do anything), tried just the fan (nothing), turned the thermostat down to the lowest (45 degrees, still nothing) and lastly tried bypassing the thermostat by directly connecting the wires.

None of that worked, so I assumed wasn't the thermostat. I looked around both the inside and outside unit for a reset switch, didn't find one. Flipped the breakers off and took the panel off the outside unit. Inside was just two main components, the contact switch and the capacitor. The capacitor was replaced last summer. I took a piece of hefty electrical wire and bridged the switch, the unit turned on. So I went out this morning and bought a new switch.

That said, I'm sure not all of that was the "bestest" way of troubleshooting, but my question is:

If the switch was bad, I replace it and the outside unit turns on, does that control the blower inside the house? I was in too much of a rush troubleshooting that when I jumped the switch I didn't check to see if the vents were pushing out air. Does the outside unit also control the inside unit?

[HayZee518]

what does the switch do? is it a safety interlock for the cover? if it is part of the control circuit check to see if it goes to the fan contactor. on the contactor there will be auxillary contacts for other circuits which may include the air handler inside.

[paul52446m]

The other day my A/C unit wouldn't turn on. I ran though some troubleshooting: , checked the breakers, tried turning on the heat (also did not do anything), tried just the fan (nothing), turned the thermostat down to the lowest (45 degrees, still nothing) and lastly tried bypassing the thermostat by directly connecting the wires.

None of that worked, so I assumed wasn't the thermostat. I looked around both the inside and outside unit for a reset switch, didn't find one. Flipped the breakers off and took the panel off the outside unit. Inside was just two main components, the contact switch and the capacitor. The capacitor was replaced last summer. I took a piece of hefty electrical wire and bridged the switch, the unit turned on. So I went out this morning and bought a new switch.

That said, I'm sure not all of that was the "bestest" way of troubleshooting, but my question is:

If the switch was bad, I replace it and the outside unit turns on, does that control the blower inside the house? I was in too much of a rush troubleshooting that when I jumped the switch I didn't check to see if the vents were pushing out air. Does the outside unit also control the inside unit?

On your electronic board of your furnace there will be a low voltage plug in or
snap in fuse, probably about 3 amp., check and see if that fuse is good. Nothing will work if that fuse is bad. Do you have a line volt fused switch at your furnace? Later Paul

[jrbryner]

Well, I went home on my lunch hour and swapped out the contact switch. Still no go.

Guess I answered my own question, but I followed the wire that controls the contact switch back the inside unit. I took off the maintenance panel took a look around and said "this is over my head" and called someone to come take a look.

On your electronic board of your furnace there will be a low voltage plug in or
snap in fuse, probably about 3 amp., check and see if that fuse is good. Nothing will work if that fuse is bad. Do you have a line volt fused switch at your furnace? Later Paul

I did see that 3amp fuse and it looked good. I'm not sure what a line volt fused switch is... there were 4 huge tube fuses. The 2 mains fed into those. There was quite a bit of circuitry and my electrical knowledge is elementary at best. Figured I'd suck it up and get a pro to work on it.

[jrbryner]

Well, proof that stress does no good.

As I said, I went home during my lunch hour to swap out the contact switch. When I did that I turned off the fuses, both inside the house and the one near the outside unit on the outside of the house. When I went to test the system, I was in such a hurry that I only turned the outside fuse back on, didn't even think about the inside ones.

So the HVAC repair guy came over. I showed him the fuses (still didn't occur to me that I hadn't turned them on). He opened up the furnace took a look around, went over and flipped on the fuses and everything started up!

Son of a gun... I thought. In the end it cost me a total $80. $20 for the switch and $60 for the repair visit. He did clean up the outside unit pretty well and checked the freon levels. Of course I did not admit to what I had done, just chalked it up to him being a miracle worker.

[HayZee518]

This just goes to prove a point. When something goes amiss, people think of the worse case scenario about what went wrong. Use a systematic approach to the problem. Do the easiest things first. Check breakers, fuses. Check interlock switches and panel and cover switches. Go to the library and brush up on electrical theory. See what makes it tick. Buy a volt ohm milliameter for troubleshooting. An analog v-o-m is indespensable. Learn what to touch and what not to touch.

[centralairunits]

The other day my A/C unit wouldn't turn on. I ran though some troubleshooting: , checked the breakers, tried turning on the heat (also did not do anything), tried just the fan (nothing), turned the thermostat down to the lowest (45 degrees, still nothing) and lastly tried bypassing the thermostat by directly connecting the wires.

None of that worked, so I assumed wasn't the thermostat. I looked around both the inside and outside unit for a reset switch, didn't find one. Flipped the breakers off and took the panel off the outside unit. Inside was just two main components, the contact switch and the capacitor. The capacitor was replaced last summer. I took a piece of hefty electrical wire and bridged the switch, the unit turned on. So I went out this morning and bought a new switch.

That said, I'm sure not all of that was the "bestest" way of troubleshooting, but my question is:

If the switch was bad, I replace it and the outside unit turns on, does that control the blower inside the house? I was in too much of a rush troubleshooting that when I jumped the switch I didn't check to see if the vents were pushing out air. Does the outside unit also control the inside unit?

I have the similar question keep monitoring........

[HayZee518]

a circuit diagram would be helpful to us to help you troubleshoot your problem. otherwise its mere guessing the problem. ANYWAY - 240 volt used for main motor, compressor, condenser fan and inside air handler. control circuit is probably 24 volt. 240 feeds to a control transformer and its secondary may be fused with a glass fuse or mini circuit breaker. fan contactor, compressor contactor, air handler contactor may have a reset button on them. a/c can cut out on low pressure limit, high pressure limit. if it is a heat pump then you'll have other equipments tied into the control circuit.