AC Compressor and Fans stop immediately

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Old 01-07-13, 06:18 AM
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AC Compressor and Fans stop immediately

Hi Guys,
My knowledge is limited and have no experience with AC so it is a little intimidating but I hope with some guidance from the good folk on this forum I can help troubleshoot my AC problem... who knows, I may learn enough to help others

My AC stopped working when we tried to switch it on this summer for the first time. It blows room temp air through the ceiling vents. I checked the outdoor unit and when turning on the AC the compressor and 2 fans will run for around 5 seconds and then stop and do not restart.

The AC unit is a 8 year old Carrier



I opened up the unit to check the capacitors as I have read this could be the cause. I found two capacitors and visually both look ok... they both seem to be for the fan as highlighted in the wiring diagram.





I am not sure how to check the freon, the low or high pressure switches etc so would greatly appreciate if I could get some guidance as to what I should check next and how.
 
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Old 01-07-13, 07:04 AM
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The capacitors are used for starting the fan and compressor motors. If they came on and ran then it is probably not a capacitor problem.

Is there an LED blinking on the control circuit board? If so, what is it blinking? The flashes are a code that will help tell you the problem.
 
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Old 01-07-13, 02:52 PM
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that looks a lot like a commercial unit..... Might want to leave it to a pro.
 
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Old 01-07-13, 04:01 PM
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Hi Pilot Dane,
There are no blinking lights on the control board. There are two lights near the breaker fuse breakers that stay solid when the unit has power.

 
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Old 01-07-13, 04:03 PM
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yep, 3 phase, that is a commercial unit.
 
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Old 01-07-13, 04:13 PM
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So the consensus is to get a professional in?
 
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Old 01-07-13, 04:19 PM
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Those can be a pain to diagnose in the field let alone to try to guide you through over the internet. Commercial units tend to have a lot more controls.
 
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Old 01-31-13, 02:45 AM
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Got the "Professionals in"

Hi Guys, I did call in a specialist. The first guy said the control board was faulty and that I need a new one. I paid the call out and diagnosis fee and never heard from him again.... maybe a good thing

Contacted another company and tech said the first guy had no idea and nothing appears wrong with the board. He measured the freon and it was empty. He put some R22, did a quick inspection for leaks and did not find any. He came back a week later and filled it saying the freon he originally put was at the same level so does not suspect any leak, if so it would be very minor.

So we started it and again it would cutout after 5 or so minutes. He reset the unit and measured the head pressure and said it was too high and it is causing it to trigger. My unit is in a 4m x 6m shed and said the lack of air flow was causing the safety to trigger. I removed the roof above the unit to eliminate any restriction. Compressor and fans do stay on now but the air is hardly at all cold. There is no condensation and the low pressure pipe is only slightly colder than ambient temp. The high side is quite warm to hot. There is also a buzzing sound coming from my compressor but it is not loud.

Could someone please give me some guidance.... I will call the tech back but would be nice to know what I should look out for before tech tells me Im best replacing the unit all together.
 
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