No Air Conditioning

Is thermostat set to cool?

Check thermostat setting.


Is thermostat calling for AC?

Make a call.


Is blower running?

If not, check -

 - Power and control fuse.

 - Check there is a call Y1 to C

 - Check there is a call G to C

 - Is there 24v. power R to C


If blower running, is outdoor unit running?

If not, is there 24v. at contactor coil?

If yes, is there 230v. power at unit?


If outdoor unit is running, what is Delta T at air handler?

Should be at least 17 degrees.  If not, what are pressures?


Is indoor coil frozen?

If so, it needs to be defrosted 1st.


What is subcooling?

Compare to listed subcooling on OD unit label.

Adjust charge per subcooling.


Is outdoor unit running?

If not:  Is there 230 V power to unit?

If not:  Check breaker.  Will breaker reset?

If not:  OHM compressor.

Is compressor grounded?  If so, condemn.

If yes:  Is contactor pulled in?

If not:  check for open pressure switch.

If yes:  Check capacitor and contactor.


If unit is running:  Check charge.

Check subcooling.

Compare to label on unit and adjust.