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9-18 ELECTRICAL TROUBLESHOOTING CHART — COOLING
Line Voltage
available at fan
speed switch
(on models so
equipped)
NO COOLING
Insure that Fuses
are good and/or that
Circuit Breakers are
On
Compressor and Fan
Motor should now
operate
See Refrigerant Circuit
diagnosis if unit still is
not cooling properly
Fan runs but
Compressor doesn't
Compressor runs but
Fan doesn't
Turn Fan Switch of Room
Thermostat to "On"
position or jump "R" to
"G" at Terminal board
Set thermostat to
"Cool," move the Temp.
lever below the present
Room Temp.
Nothing operates,
entire system
appears dead
Line voltage present
at the Transformer
Primary
24 Volts at
Transformer
Secondary?
24 Volts present at
Cool Relay?
Check Supply Circuit
for loose connections
or broken wiring
Problems indicated with
Control Transformer
Check Supply Circuit
for loose connections or
broken wiring
Problems indicated with
Room Thermostat or
Control Wiring
Does Fan Motor operate
now?
Problem indicated in
Control wiring and/or
Room Thermostat
24Volts at Coil
Terminals of Blower
Relay?
Problem indicated in
Control Wiring and/
or Room Thermostat
Problems indicated
in Blower Relay
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
No
No
No
O.K.
O.K.
O.K.
No
Is Line Voltage present
at Motor Leads?
Check Fan
Speed Switch
(on models so equipped)
or Blower Relay on later
models
Check Capacitor, is
Capacitor Good?
Replace Capacitor
Motor should run
Possible motor
problem indicated.
Check motor
thoroughly
Yes
Yes
No
No
No
Fan Motor operates,
but Compressor
doesn't
Supply Circuit
problems, loose
Connections, or bad
Relays
Replace Capacitor
and/or Start Assist
Device
Allow ample time
for pressures to
equalize
Possible Compressor
problem indicated.
See Compressor
Checks
Is Locked Rotor
Voltage a minimum of
197 Volts?
Are Capacitor and (if
so equipped) Start
Assist good?
Have System
Pressures Equalized?
Compressor should
run
Yes
Yes
Yes
No
No
No
No
Yes
Compressor and fan
motor should now
operate
See Refrigerant
Circuit Diagnosis if
unit still is not cooling
properly
Yes
No
Yes