McQuay MWM09J Manual page 70

MWM-J_(ii)
Diagnostic Guidelines
By means of pressure readings:
Data
Circuit
High side
Low side
•
High side
Low side
•
High side
•
Low side
High side
Low side
High side
Low side
Pressure
•
1. Overcharged with refrigerant.
•
2. Non-condensable gases in refrigerant circuit (e.g. air).
3. Obstructed air-intake / discharge.
4. Hot air short circuiting in outdoor unit.
1. Poor compression /no compression (compressor
•
2. Reversing valve leaking.
1. Undercharged with refrigerant.
2. Refrigerant leakage.
3. Air fi lter clogged / dirty (indoor unit).
4. Indoor fan locked / seized.
5. Defective defrost control, outdoor coil freeze up
6. Outdoor fan locked / seized (heating).
•
1. Outdoor fan blocked (cooling).
•
2. Outdoor coil dirty (cooling).
3. Indoor fan locked / seized (heating).
4. Indoor air fi lter clogged / dirty (heating).
5. Non-condensable gases in refrigerant circuit (e.g. air).
•
1. Air intake temperature of indoor unit too high.
•
Probable cause
defective)
(heating).
Troubleshooting
68