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NO COOLING OPERATION
Insure that Fuses
are good and/or that
Circuit Breakers are
on and voltage is 208/230
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
Blower/Fan doesn't
Set thermostat to
"Cool," and the Temp.
below the present
Room Temp.
Nothing operates,
entire system
appears dead
Line voltage present
at the Transformer
Primary
24 Volts present at
208/230 Volts present
at #1 relay on board?
Y terminals on
t-stat and board?
Problems indicated with
Room Thermostat or
Control Wiring
Replace board
Problems indicated
in Blower Relay
of board
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
No
O.K.
O.K.
No
Is Line Voltage present
at Motor Leads?
Check Capacitor, is
Capacitor Good?
Replace Capacitor
Motor should run
Possible motor
problem indicated.
Check motor
thoroughly
Yes
Yes
No
No
No
Supply Circuit
problems, loose
Connections, or bad
Relays/Board
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
No
No
No
No
Yes
Compressor and fan
motor should now
operate
See Refrigerant
Circuit Diagnosis if
unit still is not cooling
properly
Yes
Yes
No
Check Supply Circuit’s
jumper at transformer. If
okay, replace board
24 Volts at
“R” Terminal on board
Before continuing
check for Error
Codes, see
electronics control
diagnostics and
test mode, page 15
24V at t-stat and
control wiring?
Defective t-stat
defective control wiring
or transformer
Problems indicated with
Control Transformer
replace board
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