Lennox THA090 roottop AC compressor not running

Hi one of the 2 Lennox THA090 rooftop compressors is not running even though we set the temperature really low. The office still feels warm. We opened the cover and confirmed that one of them is running and the other is not.
However the 2 PCB control boards all seem to indicate everything is fine, based on the LED blink pattern. Any clue? Thanks a lot!
How do we test if the compressor is really broken?
The unit is about 10 years old.
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On Thursday, September 3, 2015 at 11:58:33 AM UTC-5, snipped-for-privacy@gmail.com wrote:

Simplest way to by-pass everything is to push-in the compressor contactor and see if it kicks-in.
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On 9/3/2015 12:58 PM, snipped-for-privacy@gmail.com wrote:

The usual. Check for power supply, amp draw. Disconnect, and check for open circuit, or short to ground. Check the run cap while you are in. Nothing challenging, here.
- . Christopher A. Young learn more about Jesus . www.lds.org . .
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