question for HVAC guys

if its low voltage get a meter -

Like mike said - check and see if the common has 24 volts when you ground it through the meter.

if it does
check the green wire for voltage when it calls for fan

if it does not then jump it out and give it 24 volts to see if the fan will run.


this is all dependant on what type of setup you have - but this is the most common, and low voltage as well.