A/C runs all the time even after temp is reached

Old 07-10-14, 07:38 PM
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A/C runs all the time even after temp is reached

I have a commercial building with 2 a/c units and 2 thermostats. This year we just had both a/c units changed and put 2 new thermostats in (Honeywell RTH2410b1001). The a/c works great but they will not shut off. I set them at 75/auto and both will keep running even when it gets to 70. The fan and A/C system are both running. Any insight appreciated.
Old 07-10-14, 08:26 PM
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It would be the norm in a commercial installation where the blower would run continuously but the compressor would cycle based on set temperature.

Could this be what you have..... are you sure the compressors aren't cycling ?
If the compressors weren't cycling then the temperature would go lower than the thermostat set point.
Old 07-11-14, 04:30 AM
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If they were just installed I would call the installer back and have them check it out,also are you certain that the Stats aren't set on permanent hold?check the setup manual about that.
Old 07-11-14, 05:51 AM
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Please clarify: are these packaged units that provide heat and AC, aka RTU(s)? Are they mounted on the building rooftop? OR do you have a residential furnace/air handlers with A-coils in the plenums and outdoor condensing units? MODEL #s?

Do you have a digital multimeter and are you familiar with how to use one? I would be happy to walk you through some stuff but without a meter and the knowledge of how to use it, you will probably save yourself TIME AND AGRIVATION by calling a service tech to come look at it, and if these are recent installs you certainly should call the installer and have them come look at it. I think your t-stats may need to have some of its parameters changed. If you look at the manual for the stats you will see what I am referring to. We need to know if your stats are constantly calling for cooling, and consequently sending 24v to the compressor contactor. If this sounds like gibberish to you then I would DEFINETLY get a tech out to look at what you have going on.

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