When you turn it to cool you are closing a switch to tell the unit to operate in cool mode the unit tells the blower and everything inside the unit what to do through a control board fan gets signal from relay in unit or on control board.
Thermostat auto fan doesn t work.
At the end of a heating cycle when the thermostat is satisfied the fan will automatically turn off.
1 remove the thermostat s cover.
Honeywell thermostats are designed to keep your home at a steady temperature by automatically turning on a fan to pump either hot or cold air throughout the house.
If your system has more than one fan wire you ll need to contact a pro to have your nest thermostat installed.
Fan will not come on in the on position or your fan will not come on when you turn the thermostat down in the air conditioning mode.
To adjust the thermostat.
Test to make sure you are getting 24 to 28 volts ac between the g green and c com terminals on you fan center or control board if you aren t getting 24 volts between g and c then you might have a thermostat problem a thermostat.
A furnace requires proper gas flow to the burner assembly as well as electricity to the thermostat to actuate the heater.
Because the fan only runs when your home is in a heating or cooling cycle there are times when the fan is completely off and doesn t consume any energy.
Fan doesn t work when it s auto but works fine at on in my central air furnace.
The thermostat is really just like 3 different switches.
Usually when you set your thermostat to auto or automatic the burner will ignite when the temperature falls below the temperature you set on the thermostat.
From the thermostat there will be white wire to the gas valve yellow to the a c and green to the fan.
For a mechanical thermostat with a mercury switch a small vial filled with mercury first use a small torpedo level to make sure the thermostat is mounted level on the wall.
If it isn t level it won t measure temperatures properly.
The unit is controlled from a single wall mounted panel.
The thermostat is wired to switch the power from the red to the white yellow and green as needed with the blue completing the circuit.
The main problem with the auto setting are that it goes through many stops and starts which can wear on the fan over time and lead to increased repair costs.
Some systems that need to be installed by a pro include systems with g2 g3 gm or gh wires.
