Troubleshooting AC Cooling system


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Old 06-14-17, 05:44 AM
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Troubleshooting AC Cooling system

Hello All,

My upstairs AC unit is not working. It is blowing air but not cold air. How do I troubleshoot?

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Old 06-14-17, 06:00 AM
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That is the model number of the coil, look inside the furnace for model number. Is the outside unit running? Do you have a voltmeter?
 
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Old 06-14-17, 07:22 AM
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Hello sir,

It's a 58MCB.

The outside unit is not running. I power cycled the outside breakers, notta.

I do have a volt meter.
 
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Old 06-14-17, 07:36 AM
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Is the outside unit calling to run? Is there power at the contactor?
 
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Old 06-14-17, 07:47 AM
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What do you mean when you say "calling to run"?

How to I check for power at the contactor and where is that?
 
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Old 06-14-17, 07:52 AM
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The contactor is in the outdoor unit.
Check for 24 VAC at the thermostat wires in the outdoor unit. This will show if the unit is receiving a call to run or not.
This will be live high voltage. Enough to hurt you or even kill you. Use care.
 
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Old 06-14-17, 08:17 AM
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Ok, now I'm scared. How do I locate the contactor?
 
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Old 06-14-17, 08:23 AM
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It's the switching device inside the outdoor unit that the high voltage wires run to. Should have 208-230 VAC. It's also got 24VAC control connections to power the coil.
When you take the control cover off you'll see the high voltage lugs right inside
 
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Old 06-14-17, 08:27 AM
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I failed to mention that I have two outside units. (I assume one for upstairs and one for downstairs). The one outside unit that works is the for the downstairs AC. The one that does not work is for the upstairs.
 
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Old 06-14-17, 08:32 AM
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These units should be totally separate. Shouldn't share anything including high voltage feed.
 
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Old 06-14-17, 08:47 AM
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I'm getting 240 in and out. What should I test next?

EDIT: Picture change.
 
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Old 06-14-17, 08:56 AM
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That's it.
Line voltage on the bottom. Load on top. Coil on the sides.
 
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Old 06-14-17, 08:57 AM
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Yes, I've got 240 in and out.
 
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Old 06-14-17, 09:04 AM
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And nothing is running or making noise?
 
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Old 06-14-17, 09:08 AM
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No buzzing or anything that I can hear. It's quiet. Sounds off.
 
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Old 06-14-17, 09:17 AM
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Should I check the capacitor?
 
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Old 06-14-17, 09:20 AM
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Is anything hot to the touch like the fan motor? If there is in fact 240 VAC at the load side of the contactor and nothings running, the motor protectors are open. Which to verify you'd open the disconnect, pull the motor wires and measure resistance through them, and measure resistance through R-C-S on the compressor. Open means the motor protection is open. Open with a cool motor and compressor means those are shot.
What does the capacitor measure to? Within range?
 
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Old 06-14-17, 09:28 AM
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Nothing seemed hot to the touch.

I apologize about asking the following questions:

What do you mean open the disconnect and pull the motor wires? I assume you are saying I'd measure resistance on the fan wires and on the compressor wires? How do I identify fan/compressor wires?

Can you clarify "means those are shot"? What is this referring to?
 
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Old 06-14-17, 09:35 AM
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Check the capacitor first. To see if it's in range.
 
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Old 06-14-17, 09:53 AM
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It looks like the capacitor is bulging!
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  #21  
Old 06-14-17, 10:03 AM
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I'd say it's time for a new one
 
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Old 06-14-17, 11:28 AM
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I replaced the capacitor and flipped the breaker on and BOOM it kicked right on!!

Now I'm waiting to see if it begins to cool.

Thank you for your guidance!!!!!!!!!!!!!!!!!!!!!
 
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Old 06-14-17, 01:15 PM
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It officially worked. the unit is cooling. All is back to normal.
 
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Old 06-26-17, 11:33 PM
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AC not blowing cool air but fan is working

Hi everyone! I just wanna ask some help regarding my old AC. Its a Carrier Artic Series Window AC 1Hp. I believe its already 10 yrs old. I had it repaired twice but it seemed like the tech was only for the service fee coz my unit is still unusable. First he said it was low on Freon so he fixed it, was able to use it for 2 months then it stopped cooling. SO we called him again, told him what happened then he "fixed" it again. We tried to use it but 30 mins after he left, the unit won't blow cool air again. it seemed like it was getting disconnected from the fan whatever it was. We called him again, got it "fixed", he left immediately after trying it on. It was fine but as soon as he left, when we put it in our room, in just 5 minutes, it was like an electric fan again. Whenever it kept disconnecting, the sound of the AC would make a strong noise. I never had it repaired since then. But the heat of the summer here is just too much, my 0.5Hp AC is not enough. So before I waste my time and money on another technician, I just wanna know your thoughts if my AC is still repairable, if i can i do it myself or just forget about it. Thanks in advance!!

I attached pics of my AC. To me it looks like its ready to crumble anytime but I hope it could still be fixed. TIA!
 
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