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SERVICING
21
COOLING /HEAT PUMP- SERVICE ANALYSIS GUIDE
SERVICING
POSSIBLE CAUSE
DOTS IN ANALYSIS GUIDE
INDICATE SYMPTOM
"POSSIBLE CAUSE"
System will not start
Compressor will not start -fan runs
Comp. and Cond. Fan will not start
Evaporator fan will not start
Condenser fan will not start
Compressor runs - goes off on overload
Compressor cycles on overload
System runs continuously - little cooling/htg
Too cool and then too warm
Not cool enough on warm days
Certain areas too cool, others too warm
Compressor is noisy
System runs -blows cold air in heating
Unit will not terminate defrost
Unit will not defrost
Low suction pressure
Low head pressure
High suction pressure
High head pressure
Pow er Failure
•
Test Voltage
S-1
Blow n Fuse
•
•
Inspect Fuse Size & Type
S-1
Unbalanced Pow er, 3PH
•
• •
Test Voltage
S-1
Loose Connection
•
•
•
Inspect Connection - Tighten
S-2, S-3
Shorted or Broken Wires
• • • • • •
Test Circuits With Ohmmeter
S-2, S-3
Open Fan Overload
• •
Test Continuity of Overload
S-17A
Faulty Thermostat
•
• •
•
Test continuity of Thermostat & Wiring
S-3
Faulty Transformer
•
•
Check control circuit w ith voltmeter
S-4
Shorted or Open Capacitor
•
• • •
Test Capacitor
S-15
Internal Compressor Overload Open
•
♦
Test Continuity of Overload
S-17A
Shorted or Grounded Compressor
•
•
Test Motor Windings
S-17B
Compressor Stuck
•
• •
♦
Use Test Cord
S-17D
Faulty Compressor Contactor
•
• •
Test continuity of Coil & Contacts
S-7, S-8
Compressor High Stage Not Working
• •
♦
Test Voltage to Unloader Plug, Test Plug S-17C
Open Control Circuit
•
Test Control Circuit w ith Voltmeter
S-4, S-11, S-12
Low Voltage
•
• •
Test Voltage
S-1
Faulty Evap. Fan Motor
•
•
♦
Repair or Replace
S-16
Shorted or Grounded Fan Motor
•
•
Test Motor Windings
S-16A,D
Improper Cooling Anticipator
•
•
Check resistance of Anticipator
S-3B
Shortage of Refrigerant
• •
♦
•
•
Test For Leaks, Add Refrigerant
S-101,103
Restricted Liquid Line
• •
•
•
•
Remove Restriction, Replace Restricted Part
S-112
Open Element or Limit on Elec. Heater
♦ ♦
Test Heater Element and Controls
S-26,S-27
Dirty Air Filter
•
• •
•
♦
Inspect Filter-Clean or Replace
Dirty Indoor Coil
•
• •
•
♦
Inspect Coil - Clean
Not enough air across Indoor Coil
•
• •
•
♦
Check Blow er Speed, Duct Static Press, Filter
S-200
Too much air across Indoor Coil
•
♦
•
Reduce Blow er Speed
S-200
Overcharge of Refrigerant
• •
•
♦
•
•
Recover Part of Charge
S-113
Dirty Outdoor Coil
• •
•
♦
•
Inspect Coil - Clean
Noncondensibles
•
•
♦
•
Recover Charge, Evacuate, Recharge
S-114
Recirculation of Condensing Air
•
•
•
Remove Obstruction to Air Flow
Infiltration of Outdoor Air
•
• •
Check Window s, Doors, Vent Fans, Etc.
Improperly Located Thermostat
•
•
Relocate Thermostat
Air Flow Unbalanced
•
•
Readjust Air Volume Dampers
System Undersized
•
•
Refigure Cooling Load
Broken Internal Parts
•
♦
Replace Compressor
S-115
Broken Valves
•
•
•
•
Test Compressor Efficiency
S-104
Inefficient Compressor
•
♦
•
•
Test Compressor Efficiency
S-104
Loose Hold-dow n Bolts
•
Tighten Bolts
Faulty Reversing Valve
•
♦♦♦ ♦♦♦
Replace Valve or Solenoid
S-21, 122
Faulty Defrost Control
•
♦♦♦♦♦ ♦
Test Control
S-24
Faulty Defrost Thermostat
♦♦♦♦♦♦♦
Test Defrost Thermostat
S-25
Flow rator Not Seating Properly
•
•
•
Check Flow rator & Seat or Replace Flow rator
S-111
•
Cooling or Heating Cycle (Heat Pump)
♦
Heating Cycle Only (Heat Pump)
Test Method Remedy
See Service Procedure Ref.
Complaint
No Cooling
Unsatisfactory Cooling/Heating
System Operating
Pressures