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Refrigeration Troubleshooting
Table 18 – Refrigeration Problems, Causes, and Solutions
Problem
Possible Cause
Solutions
Frosted evaporator coil, low
suction pressure
Restricted air flow
Low fan speed
Reversed blower rotation
Low refrigerant charge
Clean, or replace filters
Check fan drives
Correct wiring
Add refrigerant
Unit runs, but supplies warm
air
Loss of refrigerant
Faulty expansion valve element
Plugged filter-drier
Check leaks, add refrigerant
Replace valve element
Replace filter-drier
Compressor starts, but opens
high pressure control
Refrigerant over-charged
Air in condenser coil
Condenser fan faulty
Condenser coil dirty
Remove some refrigerant
Evacuate and recharge refrigerant
Replace fan motor
Clean condenser coil
High suction pressure, but low
superheat
Oversized expansion valve
Poor sensing bulb location
Low superheat adjustment
Replace with correct expansion valve
Relocate sensing bulb, secure to suction line
Adjust expansion valve
Unit operates continuously
Low refrigerant charge
Unit undersized
Check and recharge to nameplate
Decrease load or resize unit
Thermostat set too low, increase temperature setting
Summary of Contents for M2 Series
Page 2: ......
Page 5: ...5 Split System Piping Diagrams 98 M2 Series Startup Form 115 Maintenance Log 121 ...
Page 35: ...35 Table 1 Electric and Gas Heating Capacities ...
Page 38: ...38 Figure 5 M2 Series Unit Four Point Lifting ...
Page 39: ...39 Figure 6 M2 Series Unit Eight Point Lifting ...
Page 58: ...58 Figure 32 Supply Fan Banding ...
Page 95: ...95 Figure 52 Filter Layout Viewed from the Upstream Side of the Cooling Coil ...
Page 98: ...98 Split System Piping Diagrams Figure 53 A C Split System Piping Suction Down ...
Page 99: ...99 Figure 54 A C Split System Piping Suction Up ...
Page 100: ...100 Figure 55 A C with LAC Split System Piping Suction Up ...
Page 101: ...101 Figure 56 A C with Modulating Hot Gas Reheat Split System Piping Suction Down ...
Page 102: ...102 Figure 57 A C with Modulating Hot Gas Reheat Split System Piping Suction Up ...
Page 103: ...103 Figure 58 A C with Hot Gas Bypass Split System Piping Suction Down ...
Page 104: ...104 Figure 59 A C with Hot Gas Bypass Split System Piping Suction Up ...
Page 107: ...107 Figure 62 Heat Pump Split System Piping Suction Down ...
Page 108: ...108 Figure 63 Heat Pump Split System Piping Suction Up ...
Page 109: ...109 Figure 64 Heat Pump with Modulating Hot Gas Reheat Split System Piping Suction Down ...
Page 110: ...110 Figure 65 Heat Pump with Modulating Hot Gas Reheat Split System Piping Suction Up ...
Page 111: ...111 Figure 66 Heat Pump with Hot Gas Bypass Split System Piping Suction Down ...
Page 112: ...112 Figure 67 Heat Pump with Hot Gas Bypass Split System Piping Suction Up ...