Hello!

Im James.

Recently, my AC would not turn on. so i opened the outdoor unit up and noticed the capacitor and the terminals to be very rusty. I tested it with a meter and the capacitor was below the accepted range (28.8 instead of 35 and 3.2 instead of 5). So I changed the capacitor and it did not work. So i pushed in the contactor and the outdoor unit turned on(Is it save to assume at this point the contactor is faulty?).

So i bought a new one but it is not labeled with the L1, L2, T1, T1. how would I know which sides are which? Also the old one had one pole and new one has two, does it make a big difference?

 

While it may not be a bad idea to replace the contactor if it's rusty, it likely is not the problem. You proved that it's working by pushing in on the contactor contacts. What you need to do is to check for 24VAC at the coil terminals (usually on the side of the contactor) when the thermostat is calling for cooling. I'm guessing that you'll find that you don't have 24VAC present (that's what activates the contactor/relay to turn on the outside unit). The 24VAC comes from the house & thermostat. If you don't have 24VAC present at the outside unit, you may have a break in the cable from the house, or you may have blown the 24V fuse. You can check for the 24VAC at the contactor with the 240VAC turned off (should be an electrical disconnect located near the outside unit). Turning off the power to the outside unit makes it safer to be poking around the contactor.

 

The labels really don't mean anything other then ease of wiring. Before connecting the high voltage wires to the contactor, connect the 24 volt wires to the coil terminals. Have the stat call for cooling to pull the contactor in and then measure continuity between the poles. When you read continuity, then will be your L1 and T1 or L2 and T2. (L is line and T is load)

You could also do this manually on the bench but you will need a third hand to push in the contacts.

 

It can make a difference if you have a crank case heater on that compressor.
Some manufactures, like Carrier, often use a single pole contactor to control power to the crank case heater. The heater is wired to opposite sides of the single leg that opens when demand is not present. The crank case heater will only see 240VAC when demand isn't present.



It is far more likely that your contactor is not getting 24 volts AC to the coil.



I would check if 24VAC is present at the 2 field installed wire nuts to the outdoor unit.
Orange wire nuts in this picture...




If you do not have 24 volts outside you might check under the indoor coil for a pan full of water and a tripped float switch.

 

Thank you all for the replies! What I forgot to mention in my first post was that (only) the gas furnace was replaced earlier this year, could it have been installed incorrectly?

I also forgot to mention is when i did press the contactor in, I it remained stuck and kept the outdoor unit on despite turning of the tstat. it only turned on when the i turned off the main.

So anyway, to make thing easier to explain, I have attached a picture of the old contactor and the new one below:


I will try measuring the 24v and will be updating you guys!

Thank you again.

 

It looks like you do not have a crank case heater so your 2 pole contactor is fine.
Remember to turn off the breaker to the outdoor unit and the thermostat.
The 24 volts is provided by the indoor unit.

 

Update: I have tested the contactor and it is receiving the 240V but is not receiving the 24v it needs. the furnace does have 26.6 volts and the tstat also has 26.6 volts. Since the furnace and tstat was replaced last year, I am going to post a picture of the stat and and furnace board below:


Any suggestions and theories would be greatly appreciated!

 

Pressure switch lockout, bad timer outside, or a damaged low voltage wire to the outdoor unit.

If I do not measure 24VAC at the contactor I then check for 24VAC entering the outdoor unit.
If you are lucky it may only be a broken wire connection outside.

I don't see that your unit has a timer and it doesn't even look like you have a pressure switch.


It would be better if you could just press a reset button outside.


While you can usually look down the fan area to see if you have a reset button it is sometimes outside of the cabinet on Rheem ,Ruud and Weatherking units...



If not look for a damaged wire between the furnace and the condenser.

 

Update!

The problem turned out to be what I had suspected in the beginning. The person that changed the furnace last year did not hookup the 24 volt wire to the furnace board that leads to the outside, thus, not turning allowing the contactor to work. On the plus side, he added r22 freon, which is cool, both literally and figuratively, that cost me 250$.

Thank you all for your help!

 

How did someone add refrigerant to a non-working unit? And test the charge?

 

He just attached the wire that was not connected. After it was working, he tested the freon levels and it was not within range. After that, he added freon to the now running unit.