Carrier 50PD05 Operating And Service Instructions page 32

measured atemperature above 268 F(131 C)orthe thermistor has
short circuited (jumpered out).
The DSC willde-energize the compressor contactor and unloader
solenoid, and thealarm relay c ontacts will close c ausing aT051
alert o ntheComfortLink Control. Thecompressor will be
allowed torestart after 3 0minute delay a nd after t he DTTreads
below 250 F(120 C). T he flash code a nd alarm relay c ontacts will
bereset after t he compressor has runfor60minutes without any
other A LERTs. I f five discharge temperature ALERTs have
occurred within four h ours, the DSC willlock out t he compressor.
The lockout can only bereset bycycling the 24VAC p ower offand
on.
Flash Code 3 -- Compressor Protector Trip
This occurs when the demand signal from the system controller is
greater than 1.44VDC and there is no compressor current detected.
This could be due to the compressor's internal overload protector
being open, fuse or breaker open, power disconnected to
compressor contactor, compressor power wiring not run through
DSC current transformer port or a compressor contactor failure.
The DSC will de-energize the compressor contactor and unloader
solenoid and the alarm relay contacts will close causing a T051
alert on the ComfortLink Control. The DSC will wait for the two
minute anti-short cycle timer to time out and if the system
controller demand signal is still greater than 1.44VDC, energize the
compressor contactor again. If compressor current is detected on
the restart, the ALERT code and alarm relay output will reset. The
DSC will attempt to restart compressor as long as the system
controller demand is above 1.44VDC. There is no lockout feature
for this ALERT.
Flash Code 4 -- Locked Rotor
A locked rotor condition in the compressor is sensed by the DSC
on four consecutive start ups. The DSC will de-energize the
compressor contactor and unloader solenoid and the alarm relay
contacts will close causing a T051 alert on the ComfortLink
Control. This code results in a lockout and can only be reset by
cycling the 24VAC power off and on.
Flash Code 5 -- Demand Signal Loss
This occurs when the demand signal input has dropped below
0.5VDC. The demand input signal wire may be disconnected or
the system controller providing the signal may not be powered.
The DSC will de-energize the compressor contactor and unloader
solenoid and the alarm relay contacts will close causing a T051
alert on the ComfortLink Control. Once the system controller
demand signal input has risen above 0.5VDC, the ALERT code
and alarm relay output will reset. If the demand signal is above
1.44VDC and the anti-short cycle timer has timed out, the
compressor will restart.
Flash Code 6 -- Discharge Thermistor Fault
This occurs when the DSC is not receiving a signal from the
discharge temperature thermistor (DTT). The thermistor may be
missing, disconnected or a wire broken. The alarm relay contacts
will close and the DSC will not increase the capacity of the
compressor beyond 50% loading. This ALERT code and alarm
relay output are reset by reconnecting the DTT.
Flash Code 7 --Reserved for future use
Flash Code 8 -- Compressor Contactor Fault
This occurs when the compressor current is detected when the
system controller demand signal is below 1.44VDC. The
compressor contactor may have welded contacts or the contacts
may be mechanically jammed. The compressor will continue to run
in this condition since the DSC cannot open the compressor
contactor. The DSC will energize the compressor contactor and the
alarm relay contacts will close causing a T051 alert on the
ComfortLink Control. The unloader solenoid will remain
energized causing the compressor to run unloaded as long as the
system controller demand signal is less than 1.44VDC. If the
system controller demand is greater than 1.44VDC, the unloader
solenoid will de-energize causing the compressor to run loaded.
The ALERT code and alarm relay output are reset when current is
no longer detected while system controller demand signal is below
1.44VDC.
Flash Code 9 -- Low 24VAC Supply
This occurs when the supply voltage to the DSC has dropped
below 18.5VDC. The DSC will de-energize the compressor
contactor and unloader solenoid. The alarm relay contacts may
close if the voltage is high enough for the alarm relay to pull in.
The ALERT code and alarm relay output are reset when the supply
voltage to the DSC rises above 19.5VAC.
Table 10 -- DSC Red LED Flash Codes
LED Flash Description Action Taken Reset Probable Cause
Code by Control Method
1 Reserved for Future Use N/A N/A N/A
Flash
2 High Discharge Temperature Compressor Automatic Compressor discharge temperature is greater then 268
Flash shutdown degrees F or the DTT is shorted.
3 Compressor Protector Trip Compressor Automatic Compressor's internal overload protector being open,
Flash shutdown fuse or breaker open, power disconnected to compres-
sor contactor, compressor power wiring not run through
DSC current transformer port or a compressor contactor
failure.
4 Locked Rotor Compressor Manual Four consecutive start ups with locked rotor.
Flash lockout
5 Demand Signal Loss Compressor Automatic Signal wire may be disconnected or the system control-
Flash shutdown ler providing the signal may not be powered
6 Discharge Thermistor Fault Capacity Limited Automatic DTT may be missing, disconnected or a wire broken
Flash
7 Reserved for Future Use N/A N/A N/A
Flash
8 Compressor Contactor Fault Keep capacity Automatic Compressor contactor may have welded contacts or the
Flash at 15% contacts may be mechanically jammed
9 Low 24VAC Supply Compressor Automatic Bad connection or transformer.
Flash shutdown
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