TEST OR INSPECTION
Remove evaporator air discharge grille and check for evaporator coil icing. If icing is present check hot gas
bypass pressure regulating valve setting (suction pressure).
Do not use steam, open flame, heat gun or any other high-temperature heat source to thaw an iced
Thaw an iced coil with a lamp bulb (75-watt maximum), hair dryer or electric fan, and adjust pressure
Check compressor fan for noisy operation, high suction pressure, or excessively low discharge pressure.
indicating leaky internal valves.
10. SUCTION PRESSURE TOO LOW OR TOO HIGH
1. Check for high return air temperature.
1. Ensure condenser coil is not dirty or
2. Ensure equalizing solenoid valve is open.
2. Check for loose or missing lower front
panel, connector cover plate, circuit breaker
access cover, or filter mounting plate.
3. Check for excessive recirculation of hot
4. Check for expansion valve bulb damage or
4. Check for overcharge of refrigerant.
poor contact with suction line.
5. Test compressor.
5. Check for air in refrigerant system.
6. Test quench valve.
6. Ensure fan motor is operating.
7. Check for defective regulating valve.
7. Ensure condenser fan is not loose on shaft.
8. Test expansion valve.
8. Check for too much oil in refrigerant
9. Check for high suction pressure.
1. Ensure return air filter is clean.
1. Check for low outside air temperature.
2. Check for partially blocked discharge or
2. Check for low refrigerant charge.
return air ducts or openings.
3. Ensure evaporator coil is clean.
4. Check for low return air temperature.
5. Ensure refrigerant is fully charged.
5. Check for defective pressure regulating
6. Ensure liquid solenoid valve is closed.
6. Test compressor.
7. Ensure fan motor is operating.
9. Test expansion valve.