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Honeywell thermostat with EIM won't shut off my AC

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4.3K views 13 replies 6 participants last post by  QiangSuper  
Q
#1 ·
Hello guys,

I have a question for you about my honeywell thermostat with the EIM (equipment integrated module). The current issue is that it won’t shut off the system when the room temperature reaches the setting temperature.

For example, the current temperature outside is 95F and the temperature is set to 78F. After around 40 to 50 mins running, the room temperature will drop to 78F. But the AC won’t shut off, and will keep running. If I lower the temperature to 77F, the room temperature can go down to 77F, but it won’t stop. But if I higher the temperature to 79F. Sometimes it might stop the AC, but sometimes simply not. And a couple minutes later, the room temperature will go up to 79F.

I already replaced it with a new thermostat, but this issue lasts. Do you have any idea what went wrong? Thanks for your help.

The whole system was installed in 2019. The component detail is listed here:

Thermostat: TH8320R1003,

EIM: THM5421R1021,

AC: EL280DF090E48B-01
 
H
#4 ·
That thermostat only uses 24v to power, and then redlinks to the eim.


Poster, i hate to burst your bubble, but thats normal operation.
It doesnt just shut off like a light switch.
There are .1 degree it measure in the back of the thermostat that you cant see.


If it OVERCOOLS, being that it actually cools below the setpoint, then you probably have dehumidification turned on with overcool.
 
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Q
#6 ·
Thanks so much for sharing. My concern is that if the system is operating normally? It won't overcool, as you can see, the system has the ability to cooler the room to 77, but if I set to 78, it will stay on 78 and the AC is running constantly (like 5 hours). I am not sure if this will cause damage to AC and furnace since the machine is running for quite a long time.
 
#8 ·
Most wear happens when the unit starts not while it's running. You should be more concerned if it's shutting off every hour when it's hot out.
 
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