Carrier 40GXC Service Manual page 19

DIAGNOSTIC CHARTS (CONT.)
Is unit running in outdoor Is unit running in outdoor
ambient higher than ambient higher than
110 °F? 110 °F?
No No
Outdoor coil clean? Outdoor coil clean?
Yes Yes
Check outdoor coil Check outdoor coil
temperature thermistor . temperature thermistor .
Chart 4, ok? Chart 4, ok?
Yes Yes
Check motor for open Check motor for open
or short. Ok? or short. Ok?
No No
Check output on outdoor Check output on outdoor
board. Ok? board. Ok?
No No
Replace outdoor board Replace outdoor board
Replace motor Replace motor
No No
Outdoor motor ok? Outdoor motor ok?
Yes Yes
Replace compressor Replace compressor
Yes Yes
Beyond operating range Beyond operating range
No No
Clean coil. Clean coil.
Problem persists? Problem persists?
No No
Replace thermistor . Replace thermistor .
Problem persists Problem persists
Yes Yes
Replace outdoor motor Replace outdoor motor
Fig. 32 – High Condensing Temperature
Is unit running in outdoor Is unit running in outdoor
ambient higher than ambient higher than
110 °F? 110 °F?
No No
Outdoor coil clean? Outdoor coil clean?
Yes Yes
Check connections from Check connections from
OD board. Loose, corroded, OD board. Loose, corroded,
or high resistance? or high resistance?
No No
Yes Yes Check output on Check output on
outdoor board. Ok? outdoor board. Ok?
Connect low side gauge at Connect low side gauge at
suction service valve. suction service valve.
Measure discharge temp.* Measure discharge temp.*
Yes Yes
Check amp draw to
Check amp draw to
No No
compressor? Values within compressor? Values within
range? range?
Yes Yes
Replace outdoor board Replace outdoor board
Fig. 33 – Compressor Overcurrent Protection
No No
Problem solved Problem solved
Yes Yes
No No
Problem solved Problem solved
Yes Yes
Yes Yes
Beyond operating range Beyond operating range
No No
Clean coil. Clean coil.
Problem persists? Problem persists?
Yes Yes
Yes Yes
Clean/repair connection Clean/repair connection
Problem persists? Problem persists?
Yes Yes
No No
Replace outdoor board Replace outdoor board
No No
High head, high suction? High head, high suction?
Yes Yes
Unit is overcharged. Unit is overcharged.
Reclaim charge and weigh Reclaim charge and weigh
in correct charge. in correct charge.
*Measure discharge temperature at the sensor on the discharge *Measure discharge temperature at the sensor on the discharge
tube. See Appendix A5 tube. See Appendix A5
19
No No
Problem solved Problem solved
No No
Problem solved Problem solved
No No
High head, low suction? High head, low suction?
Yes Yes
Restriction in refrigeration Restriction in refrigeration
circuit. circuit.
A09364
A09365