# Furnace/AC turns on but won't turn off



## gymjunkie (Jun 13, 2017)

I have to manually flip the switch on the furnace that turns it on/off otherwise it will just run forever which is a PITA to run up and down the stairs 4-7 times a day. I have never chatted about this stuff before so I have no idea at all what information you need so you're going to have to ask everything you need to know, sorry about that.


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## nealtw (Jun 13, 2017)

Welcome to the site.

Do you have a programmable thermostat or the one that has the little pointer?


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## gymjunkie (Jun 13, 2017)

nealtw said:


> Welcome to the site.
> 
> Do you have a programmable thermostat or the one that has the little pointer?



Thanks for the welcome! It's digital but not programmable and fresh batteries was the only attempt I made so it's not the batteries lol


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## nealtw (Jun 13, 2017)

gymjunkie said:


> Thanks for the welcome! It's digital but not programmable and fresh batteries was the only attempt I made so it's not the batteries lol



The next step I think would be to disconnect the Tstat to prove it is thew problem or if the furnace keeps going it would be a problem at the furnace.

I am hoping someone with more knowledge would jump in here.


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## gymjunkie (Jun 13, 2017)

nealtw said:


> The next step I think would be to disconnect the Tstat to prove it is thew problem or if the furnace keeps going it would be a problem at the furnace.
> 
> I am hoping someone with more knowledge would jump in here.



Ask me to change the tstat on a car and Ill jump right to it but on the furnace I wouldn't even know where to begin


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## nealtw (Jun 13, 2017)

gymjunkie said:


> Ask me to change the tstat on a car and Ill jump right to it but on the furnace I wouldn't even know where to begin



Open the T stat and take a picture of the wires and remove one at a time and see if the furnace quits.  It is just 24 volts dc, no big deal.


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## Snoonyb (Jun 13, 2017)

What is the age of the system and the mfg. model #?


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## gymjunkie (Jun 13, 2017)

Snoonyb said:


> What is the age of the system and the mfg. model #?



The system was put in just 4 years ago with an energy assistance package from our electric company and it was new when they installed it. It's a Payne (love the irony), model number pg9mab036080acsa


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## kok328 (Jun 13, 2017)

Does the thermostat show that it has reached the setpoint?


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## nealtw (Jun 13, 2017)

kok328 said:


> Does the thermostat show that it has reached the setpoint?



That was to easy.:thbup::thbup:


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## gymjunkie (Jun 14, 2017)

kok328 said:


> Does the thermostat show that it has reached the setpoint?



Yes it does show that it has


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## nealtw (Jun 14, 2017)

gymjunkie said:


> Yes it does show that it has



There are three things it can be.
the Tstat. 
the wire
the furnace.

So disconnect the Tstat.
If you have no change then find the same wires at the furnace and disconnect them.
If no change then it will be looking at the control board or something.

Just take pictures or make good notes before you pull wires.


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## gymjunkie (Jun 15, 2017)

Ok so I havent gotten to pulling out the tstat yet (my stressed brain was thinking you meant something inside the furnace (hence the car tstat reference), boy did I feel like an idiot this morning when it finally hit me lol) but I did get everything quiet in the house and found that the A/C does in fact turn off, it sounds like it's just the fan that won't shut off. 

It's way too hot to test the furnace right now so don't ask lol


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## nealtw (Jun 15, 2017)

gymjunkie said:


> Ok so I havent gotten to pulling out the tstat yet (my stressed brain was thinking you meant something inside the furnace (hence the car tstat reference), boy did I feel like an idiot this morning when it finally hit me lol) but I did get everything quiet in the house and found that the A/C does in fact turn off, it sounds like it's just the fan that won't shut off.
> 
> It's way too hot to test the furnace right now so don't ask lol



Older systems had a switch at the furnace where you could change the fan from automatic to continuously on and I think you might be able to do that at the Tstat. Pulling the wires would show that it at the Tstat or not.

The fan is controlled by heat so when the furnace shuts off the fan will run until the controls read a lower temp.


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## kok328 (Jun 15, 2017)

Change the setting on the thermostat from "Fan = On" to "Fan = Auto" or "Fan = Cool"


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