Carrier FLOTRONIC II 30GN040-420 - Manual (Page 51)

Code 21 Reset thermistor failure (applies only to installa-
tions having external temperature reset) (alert)
If temperature measured by this thermistor is outside range
of –40 to 240 F (–40 to 116 C), reset function is disabled and
unit controls to normal set point. If temperature returns to
the acceptable range, reset function is automatically en-
abled. The cause of this fault is usually a bad thermistor,
wiring error, or loose connection.
Code 22
Compressor A1 discharge pressure
transducer failure (alert)
Code 23 Compressor B1 discharge pressure
transducer failure (alert)
Code 24 Compressor A1 suction pressure transducer
failure (alert)
Code 25 Compressor B1 suction pressure transducer
failure (alert)
Code 26 Compressor A1 oil pressure transducer failure (alert)
Code 27 Compressor B1 oil pressure transducer failure (alert)
If output voltage of any of these transducers is greater than
5 v, affected circuit shuts down without going through pum-
pout process (Alerts 24-27). Other circuit continues to run.
Reset is automatic if output voltage returns to the acceptable
range, and circuit start-up follows normal sequence. The cause
of this fault is usually a bad transducer or a wiring error.
Code 28
Low transducer supply voltage (alarm)
If transducer supply voltage is less than 4.5 v or greater
than 5.5 v, unit shuts down without going through pumpout
process. Reset is automatic if supply voltage returns to the
acceptable range, and circuit start-up follows normal se-
quence. The cause of this fault is usually a faulty trans-
former or primary voltage is out of range.
LEGEND
C — Contactor
CB — Circuit Breaker
COM, COMM — Communications Bus
CPCS
— Compressor Protection
Control Module
CR — Compressor Contactor Relay
DGT — Discharge Gas Thermostat (Optional)
DSIO — Relay Module (Low Voltage)
HPS — High-Pressure Switch
LV — Low Voltage
NC — Normally Closed
NO — Normally Open
PL — Plug
PWR — Power
SNB — Snubber
TB — Terminal Block
TRAN — Transformer
U — Unloader
Fig. 11A — 24-V Safety Circuit Wiring (040-070)
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