Description
The pressure in the liquid line is above the acceptable maximum and the pressure switch has opened the safety circuit. A loss of 24v to the green EcoNet outdoor board will also cause this
Expected Operation
If the event occurs within the same call 3 times, the system will switch from an Alert to an Alarm and lock the unit out for 4 hours.
Cause
High pressure can be caused by overcharge, dirty outdoor coil, or faulty fan motor in cooling mode. In heating mode, check indoor motor, airflow, filter, and coil cleanliness. Loss of 24v to outdoor unit control will also be suspect if HPS circuit is OK
Solution
Check refrigerant charge - compare pressure readings to published values for the unit at the current ambient temp. Adjust refrigerant charge level as necessary.
Verify there is a solid 24vac to terminals R and C this could be missing due to a weak connection where wires go back to air handler or possibly if someone installed some sort of safety such as a float switch in the Red wire leading to outdoors, or an improperly installed utility break relay.