Geo unit has been locking out on high pressure and low air coil temp. The unit was running when I arrived. I checked out the system operation and performance. Found the air coil was dirty. I blew nitrogen through it but it’s still dirty. I recommend we come back with evaporator coil cleaner and spray the coil. Checked the pumps, they were working. Checked temperature rise, had 23 which is good. Loopfield has pressure. Checked water temperature drop. The incoming water is 30 and leaving water is 25. Those temperatures are low. The loopfield might be partially air locked per Jamie. Unit is heating at this time. We recommend coming back to clean the evaporator coil and perform maintenance on the furnace first. If the unit is still locking out after cleaning it we will have to flush out the loopfield.