Compressor not starting
 

My 5 ton geothermal unit compressor does not start unless I hold in the
contactor.

1. What makes the contactor work ? I hear a click when I set the thermostat to call for cool or hot air.

2. By manually engaging the contactor, does this mean the contactor is bad ?

Thanks for any help.

Marvin

the contactor is engaged by a 24VAC or 120VAC coil.
either the coil is bad or your not getting power to the coil on the contactor.
check your transformer if it's a 24VAC coil.
there could be a whole host of other reasons but, it may be premature at this point.
post back your findings.