Is it the a/c or the thermostat

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Old 03-17-15, 06:04 PM
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Is it the a/c or the thermostat

All of a sudden the thermostat is showing high readings. I have it set at 77 and it usually reads as 78. Now it reads at 81 or 82 before it kicks on. Normally, when it reads hi or lo and I turn it up or down it starts or stops right away. Now it does not do that. The batteries are good and no flashing messages show up. So, what could my problem be?
 
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Old 03-17-15, 08:53 PM
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It sounds like the thermostat is bad. When your system does come on does it cool good? Does it cool down to the 77?
 
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Old 03-17-15, 11:22 PM
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If it is actually starting the A/C running but at the wrong temperature..... that does indicate a thermostat problem.
 
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Old 03-18-15, 04:45 AM
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Thanks for the info. Yes, the a/c cools ok. Maintenance is due in a few months. I just wanted to get a jump start if there was a problem brewing. How difficult is it to replace the thermostat?
 
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Old 03-18-15, 05:23 AM
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It's very easy to replace the thermostat. Make a note of which wires go to which terminals on the old thermostat, and connect them to the same terminals on the new thermostat. Be sure to turn off the power to the furnace/air handler (where the 24VAC transformer is located) before disconnecting any wires.
 
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Old 03-18-15, 01:24 PM
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Thanks a lot. I'll give it try.
 
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Old 03-19-15, 11:08 AM
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Where you are in Fl, do you have a humidity control set up for your system? If so check the setting on it that could be causing your cooling to be locked out. Very common in condos in Fl.
Geo
 
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Old 03-19-15, 11:58 AM
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I am not sure if it has a humidity control, nothing that I can see anyway. Not in a condo. I've had this a/c unit for 7 years and this is the first time with this issue. Although the batteries were good, I changed them anyway and reset the thermostat.
The strange thing now, I set the temp at 75 instead of 77 and, so far, the reading seems to be holding at 76. I tried several times calling the place that makes them but could not get through. So if it holds at 76 I won't worry about it and have it checked when maintenance is done in June.
 
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Old 03-21-15, 07:02 PM
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I'm back! The 76 temp reading didn't last very long. It would go to 81-82 even though it was set on 75. I just went to Home depot and got a new thermostat. It ran for about 20 minutes. Of course the customer service/tech support is closed until Monday.

Any ideas on what to check?
 
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Old 03-22-15, 06:04 AM
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Check the outside unit and see if the fan (usually on top) is running when the A/C is running. If the fan is not running when the A/C is on, that is most likely your problem. The fan pulls cool air through the condenser coils and also helps keep the compressor (inside the outside unit) from overheating. If the fan isn't running, the compressor will overheat and shut itself off. The outside unit may be either on the ground (hopefully), or it may be on your roof, depending upon the type of installation you have.

If the fan isn't running when the A/C is on, take a stick and try to give the fan blade a nudge to get it turning. If the fan then runs, the most likely cause is a bad fan capacitor. If the fan doesn't start up with a nudge, then the fan motor is possibly bad and will need to be replaced. While you're outside, listen to the outside unit. Is the compressor running?
 
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Old 03-22-15, 01:57 PM
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Thanks, will do. Waiting for the a/c to crank on and will check the fan, etc.

The a/c (with the new stat) came on again around 10:30PM and ran for a bit. Temp set at 75 but stat read at 80. I thought about putting the old stat back since they both are doing the same thing.

This morning it was running and holding and reading at 76. Had to go out for a few hours and when I got home it was back on 80. My daughter said it seemed to be running ok.

Anyway, I am going to call tomorrow and set up the maintenance check.
 
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Old 03-22-15, 04:33 PM
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The a/c came on about 10 min ago. I had set it down to 63 around 4:00, so it took over 2 hrs to kick in. The temp reads at 82.

The fan works and the compressor works.
 
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Old 03-23-15, 12:00 PM
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You don't, by any chance, have any kind of "energy management" device (usually installed by the power company or their contractor) on that unit do you?
 
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Old 03-23-15, 12:42 PM
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Yes, I do have the energy device installed but, after having the service guy here this morning, it turned out to be something completely different. The coils were really dirty and the stuff was/is falling down blocking the water flow. I had a condensate pump installed last year because the a/c was always leaking.

I am scheduled for coil cleaning early morning. Of course the cost is not covered by service contract or extended warranty.

I put the old stat back and returned the one I installed on Fri. didn't like the new one at all but it was the only non-programmable they had.

I know all a/c have problems but when this Trane leaves the station I'll go back to Rheem.
 
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Old 03-23-15, 03:29 PM
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Coil cleaning isn't included in your service contract???? What do they do for thier money?
 
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Old 03-23-15, 05:36 PM
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I was going to scan the info but remembered, my printer bit the dust yesterday, waiting on new one.
 
 

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