Reznor MASA Unit Installation Manual - Manual (Page 35)

Form I-COND, P/N 220746R6, Page 35
SYMPTOM POSSIBLE CAUSE REMEDY
E. Noisy
compressor
1. Refrigerant overcharge. 1. Check subcooling and superheat. (See Paragraph 9.2)
2. Compressor operating in reverse. 2. Switch the 3 phase line voltage wiring connections.
3. Liquid floodback. 3. Check thermostatic expansion valve setting. Check for refrigerant
overcharge. Check subcooling and superheat. (See Paragraph 9.2).
4. Tubing rattle. 4. Dampen tubing vibration by taping or clamping. Carefully bend tubing
away from contact where possible.
F. High suction
pressure
1. Excessive load on evaporator coil. 1. Check for high entering wet bulb temperature. Check for excessive air.
2. Compressor is unloaded. 2. Check head pressure; check thermostatic expansion valve if not
functioning properly; check pressure drop across filter drier.
3. Expansion valve not secured to suction line or
valve defective.
3. Check operation of the thermostatic expansion valve. Ensure bulb is
secure and insulated (See Paragraph 6.1.3.4).
G. High discharge
pressure.
1. Thermostatic expansion valve setting. 1. Check thermostatic expansion valve and superheat.
2. Air inlet to condenser dirty or obstructed. 2. Check for proper clearances and possible air recirculating.
3. Refrigerant charge. 3. Check subcooling and superheat. See Paragraph 9.2.
4. Condenser fan motor defective. 4. Check operation of condenser fan motor(s).
5. Non-condensables in the system 5. Clean the circuit.
H. Suction
pressure is too
low.
1. Refrigerant undercharge. 1. Check pressures and subcooling. See Paragraph 9.2.
2. Blower running backward. 2. Interchange any two wires of 3 phase wiring connections.
3. Loose blower, pulley, or belts. 3. Check air handler drive pulley alignment and belt tension.
4. Defective or improperly adjusted expansion valve. 4. Check superheat (Paragraph 9.2) and thermostatic expansion valve.
5. Dirty filter. 5. Check filter and evaporator coil. Clean or replace as needed.
6. Too little air flow or low entering air temp. 6. Check airflow and entering air wet bulb conditions.
7. Restriction in suction or liquid line. 7. Check refrigerant circuit for restriction.
J. Head pressure
too low.
1. Insufficient refrigerant charge. 1. Check superheat and subcooling (Paragraph 9.2). Check for a leak.
2. Defective / improperly adjusted expansion valve. 2. Check superheat and thermostatic expansion valve.
3. Low suction pressure. 3. See “H. Suction pressure too low” above.
4. Defective compressor. 4. See “F. High suction pressure” above.
K. Compressor
short cycles.
1. Thermostat location or malfunction. 1. Check thermostat/control.
2. Improper refrigerant charge. 2. Check subcooling and superheat (Paragraph 9.2).
3. Defective high or low pressure control. 3. Check high or low pressure switch. Replace as needed.
4. Liquid floodback. 4. Possible tight bearings.
5. Defective expansion valve. 5. Check thermostatic expansion valve and superheat.
6. Poor air distribution. 6. Check ductwork for recirculating.
7. High discharge pressure. 7. See “G. High discharge pressure.” above.
8. Leaking discharge valves in compressor. 8. See “F. High suction pressure” above.
L. Running cycle
is too long or
unit operates
continuously.
1. Refrigeration undercharged. 1. Check subcooling. (Paragraph 9.2)
2. Dirty filter or evaporator coil. 2. Check filter, coil, and airflow.
3. Dirty or clogged condenser coil. 3. Check coil and airflow.
4. Air or other non-condensables in system. 4. Check equalized high side pressure with equivalent outdoor
temperature.
5. Defective compressor. 5. See “F. High suction pressure” above.
6. Restriction in suction and liquid line. 6. Check for restrictions in refrigerant circuit.
7. Control contacts stuck. 7. Check wiring.
M. Supply air
temperature is too
high.
1. Refrigerant undercharge or leak in system. 1. Check subcooling and check for leaks.
2. Evaporator plugged with dirt or ice. 2. Check evaporator, airflow and filter.
3. Improperly adjusted or defective expansion
valve.
3. Check superheat and thermostatic expansion valve. Check
thermostatic expansion valve bulb.
4. Defective compressor. 4. Check compressor for proper operation.
5. High discharge pressure. 5. See “G. High discharge pressure” above.
6. Airflow is too high. 6. Check external static pressure.
N. Supply air
temperature is too
low.
1. Airflow is too low. 1. Check evaporator coil; check filters; check for closed dampers or
grills; check drive for loose parts, belts, or misalignment; check external
static pressure.
2. Return air temperature too low. 2. Check entering air wet bulb conditions.
O. Liquid line is
too hot.
1. Refrigerant undercharge. 1. Check subcooling.
2. Dirty/plugged condenser coil. 2. Clean coil.
3. Non-condensables in the circuit. 3. Clean the circuit.
4. Condenser fan motor defective. 4. Check condenser fan motor(s).
5. High discharge pressure. 5. See "G." above.