Can a blower fan work only when the thermostat is set to fan on?
Fan will work only when thermostat set to fan on. Thank you for the question, Anon, as it’s a common A/C, or heating fan operating problem that needs to be understood: I put it as “The blower fan runs only in the MAN-ON switch but won’t run on AUTO”.
What does it mean when your thermostat says Cool but not working?
If the “cool on” or the snowflake icon is flashing, the thermostat is in delay mode, which can take up to 5 minutes. This delay is to protect your equipment from short cycling. 3. If the thermostat indicates a call for cool, verify that the furnace door is securely closed and that the power switch on the furnace is set to On. 4.
Can a faulty thermostat cause an air conditioner to fail?
A faulty thermostat may be to blame if the air conditioner short cycles and runs almost nonstop, the living space seems warmer than your desired temperature setting, or you suddenly experience a cooling system failure. Learning how to troubleshoot these issues can help you avoid an unnecessary and costly service call.
Why does my blower fan run only on auto?
I put it as “The blower fan runs only in the MAN-ON switch but won’t run on AUTO”. This problem can happen in both heating and cooling mode. Rule out bad fan motor or no power to fan.
Why is my HVAC blower not turning on?
So when calling for cooling, the thermostat usually energizes both Y for cooling, and G to turn on the blower. Since you say the blower doesn’t come on for cool calls, or when the fan switch is moved to the ON position. That points to a problem with the “fan circuit”.
What happens if the thermostat is not set?
This is in effect exactly the same as what happens when the thermostat calls for heat – it’s acting as a simple on-off switch (in response to room temperature). If the burner starts, the plenum heats, and the blower starts as it should, then you have isolated the problem back to the thermostat or its wiring.
What to do when your HVAC fan won’t work?
Since the blower works for heat, you might try putting the wire that’s on the HEAT terminal on the COOL terminal. If the blower fires up, you know it’s a problem with the motor. WARNING: Don’t run the system this way for long, you’re just checking to see if the blower starts.
What happens when you take the thermostat off a HVAC blower?
Even with the thermostat removed, it randomly turns on. It has gone a day without coming on (thermo off the wall the entire time) then just cycles itself on. Just blower, no heat or AC.
Why does my HVAC blower fan not work?
Measure voltage between C (or the common side of the transformer), and the wire that was connected to Y. You should get about 24 volts AC. If you don’t there’s a problem with the thermostat, or the wire between the thermostat and furnace. If you do, then the problem likely lies within the control board.
What to look for when your thermostat is not working?
We cover how the thermostat works, the color code, what to look for, simple diagnosis of possible condensate float switch problems, voltages, low voltage fuses, 24v safety sensor wires, and anything else stopping the voltages from turning on your furnace or air conditioning unit.
How can I get power to my HVAC blower?
After review of the diagram, there appears NO way power can get to the blower motor except via the 24 volt transformer voltage, which only goes thru my thermostat. There is no other way to get power to the blower. Thus there likely has to be a short in the thermostat wiring between the furnace and my thermostat.
