AC Cooling Intermittently

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Old 07-06-14, 10:25 PM
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AC Cooling Intermittently

My AC has established a pattern of only blowing cold air from about 3pm til 7. In the last 3 or 4 days, I can't get any cold air during the evening. My AC guy is convinced my problem is the thermostat bc my unit appears to be in good shape. Though, when I switched my downstairs t-stat (problem) with my upstairs t-stat (no problem), I had no change.

What could cause a problem like this? What should I check?

Thanks!
 
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Old 07-06-14, 10:36 PM
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Welcome to the forums.

You have two distinct pieces of equipment. You have the outside compressor unit and the inside air handler or furnace. You need to determine if either or neither is working.
 
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Old 07-06-14, 10:41 PM
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When I'm not getting cold air, neither unit is doing anything. But a few hours later everything works fine.
 
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Old 07-06-14, 11:01 PM
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One thing you can check for is a plugged drain line from the furnace/air handler. If you have a condensate pump it could be malfunctioning. They are usually setup to shut the A/C down if there is an overflow condition.

I doubt it's a thermostat problem. You may need the assistance of a voltmeter to check and find out where the control voltages are getting lost.
 
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Old 07-07-14, 04:23 AM
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When U switched the t-stats - no problem.

The problem T-stat didn't accidently get programmed to raise the temp, or something, during that program cycle?

Check all of the programmable cycle periods.

You could remove the batteries then replace them in a few minutes & entirely reprogram the T-stat so U know it is correct.
 
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Old 07-07-14, 06:06 AM
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The thermostat is not programmable. But I will try resetting with battery removal.
 
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Old 07-07-14, 08:51 AM
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I agree with PJmax. Something may be shutting it down and a plugged drain makes sense, if there is a safety hooked up to either a condensate pump, or an overflow switch.
 
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