Air handler turns on intermittently even when set temp is reached.


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Old 11-03-17, 07:22 AM
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Air handler turns on intermittently even when set temp is reached.

My HVAC is a heat pump system, the air handler inside is a Goodman aspf183016ea. The whole system/house is about 3 years old, and is all electric. I recently moved into the home and noticed that the air handler blower would continue to run even when the set temp was reached, whether heating or cooling; the condenser unit outside would shut off correctly, but the fan would continue to blow. This even occurs when the thermostat is set to off (fan is set to auto). The fan would occasionally shut off, but it was very rare. I had a technician take a look and he said the issue was probably a bad relay switch. He replaced it, but I noticed the issue was still present and called him back. He said he wasnít sure why it would still be doing this, but replaced it again with a ďheavy dutyĒ one and just ensured me that even if the fan blows, it wouldnít draw much power.

Now, the fan does shut off when the set temp is reached, but it keeps turning on and off in 10-15 minute increments; Iíve timed it, and itís not exact every time. Iíve also noticed when the fan does come on (when the set temp has been reached and shouldnít be on), I hear an audible noise from the blower unit, like a switch activating, before the fan turns on. Iíve since replaced the thermostat (formerly a Honeywell FocusPro 6000) with a Nest Learning Thermostat E. All the connections were made accurately, and the heating/cooling/fan controls work properly, however the fan still switches itself on and off in the same intermittent manner. I know the Nest thermostat has a setting to run the fan every hour for a set amount of time but I havenít activated this.

Is the problem still with the relay switch, and should I have a technician take a look again? What else could the problem be?
 
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Old 11-03-17, 10:23 AM
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Welcome to the forums.

Since you have a heat pump system...... you have electric back up heat. That back up heat is controlled by a sequencer. It's a timer/relay that turns on the heat and the blower at the correct times. The sequencers can go bad and cause that problem.

There should be an additional sticker or number after the model number denoting the heat setup. It may have been written in with pen.
 
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Old 11-04-17, 09:36 AM
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Thermostat setting

Your thermostat is in all likelihood set on circ. If this really bothers you, and you would rather let the heated air stay up on the ceiling and the colder air Seattle on the floor, switch the fan mode switch to auto. That circ mode turns the fan on every once in a short while to help keep the air from stratifying. This prevents excessive fuel consumption and redistributes the already warmed air back down to living areas. Then again, if you donít have this circ option, the problem lays elsewhere. A strip heater not shutting off because of a sequencer hanging up is possible too. Theyíre cheap, and cheaply made, and donít last for beans....
 
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Old 11-06-17, 07:47 AM
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I've checked my thermostat and there is a setting to activate the fan every hour but it is not set. The fan is set to auto, which should mean it will only turn on when there's a demand for heating/cooling. I don't believe there's any other setting thermostat wise that would cause the fan to do this.

If the the blower is supposed to circulate the air like this, then I'm fine with it. As the technician said, it shouldn't draw much power, and my latest bill was not as high as I anticipated so it confirms it. I just want to be sure the blower isn't needlessly running and wasting money. I will try and locate the heat setup.
 
 

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