SERVICING
33
Complaint No Cooling / Heating Unsatisfactory Clg / Htg
System
Operating
Pressures
POSSIBLE CAUSE
DOTS IN ANALYSIS
GUIDE INDICATE
"POSSIBLE CAUSE"
SYMPTOM
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 clg / htg
Too cool and then too warm
Not cool enough on warm days
Certain areas to cool others to warm
Compressor is noisy
System run blows cold air (Heating)
Unit will not terminate defrost
Unit will not defrost
Low suction pressure
Low head pressure
High suction pressure
High head pressure
Test Method
Remedy
See Service Procedure Ref.
Power Failure
•
Test Voltage S-1
Blown Fuse
•••
Imspect Fuse Size & Type S-4
Loose Connection
•••
Inspect Connection - Tighten S-2
Shorted or Broken Wires
••••••
Test Circuits With Ohmmeter S-3
Open Overload
•••
♦
Test Continuity of Overload S-17A
Faulty Thermostat
•• •
Test continuity of Thermostat & Wiring S-3
Faulty Transformer
••
Check control circuit with voltmeter S-4
Shorted or Open Capacitor
•••
Test Capacitor S-15
Shorted or Grounded Compressor
••
Test Motor Windings S-17B
Compressor Stuck
••
Use Test Cord S-17C
Faulty Compressor Contactor
•• ••
Test continuity of Coil & Contacts S-7, S-8
Faulty Fan Relay
•
Test continuity of Coil And Contacts S-7
Open Control Circuit
•
Test Control Circuit with Voltmeter S-4
Low Voltage
•••
Test Voltage S-1
Faulty Evap. Fan Motor
••
Repair or Replace S-16
Shorted or Grounded Fan Motor
••
Test Motor Windings S-16
Improper Cooling Anticipator
••
Check resistance of Anticipator S-3
Shortage or Refrigerant
•• ••
Test For Leaks, Add Refrigerant S-103
Restricted Liquid Line
•• ••
Replace Restricted Part S-112
Dirty Air Filter
••• •
♦
Inspect Filter-Clean or Replace
Dirty Indoor Coil
••• •
♦
Inspect Coil - Clean
Not enough air across Indoor Coil
••• •
♦
Speed Blower, Check Duct Static Press S-200
Too much air across Indoor Coil
•
Reduce Blower Speed S-200
Overcharge of Refrigerant
•• • ••
Release Part of Charge S-113
Dirty Outdoor Coil
•• •
♦
•
Inspect Coil - Clean
Noncondensibles
•• •
Remove Charge, Evacuate, Recharge S-114
Recirculation of Condensing Air
•• •
Remove Obstruction to Air Flow
Infiltration of Outdoor Air
•••
Check Windows, 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
Inefficient Compressor
•
♦
••
Test Compressor Efficiency S-104
High Pressure Control Open
•
Reset And Test Control S-12
Unbalanced Power, 3PH
•••
Test Voltage
Wrong Type Expansion Valve
•• •
Replace Valve
Expansion Device Restricted
••• • ••
Replace Valve
Expansion Valve Bulb Loose
••
Tighten Bulb Bracket
Inoperative Expansion Valve
•• •
Check Valve Operation S-110
Loose Hold-down Bolts
•
Tighten Bolts
Faulty Reversing Relay
♦♦
Test continuity of Coil And Contacts S-7
Faulty Defrost Relay
♦♦
Test continuity of Coil And Contacts S-7
Faulty Reversing Valve
•
♦♦♦
••
Test Valve Operation S-21
Leaking Check Valve/Orifice
•••
Replace Check Valve
Faulty Defrost Timer
♦♦
Test Timer Operation S-23/24
Faulty 30/60 Control
♦
Test Control S-25
Additional Opt Elect. Heat Req.
♦
Run Load Calculation, Add Heaters
Open fuse or limit in Elect. Htr
♦
Inspect Fuses and Limits S-50
O.D. Thermostat setting to Low
♦
Raise Setting
•
Clg or Htg Cycle
♦
Heat Pump Cycle only
COOLING OR HEAT PUMP - SERVICE ANALYSIS GUIDE
S-1, S-4
Recover part of charge
S-24
S-53
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