Carrier 48/50PD05 manual Flash Code 4 ⎯ Locked Rotor, DSC Red LED Flash Codes

48/50PD

measured a temperature above 268 F (131 C) or the thermistor has short circuited (jumpered out).

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 compressor will be allowed to restart after 30 minute delay and after the DTT reads below 250 F (120 C). The flash code and alarm relay contacts will be reset after the compressor has run for 60 minutes without any other ALERTs. If five discharge temperature ALERTs have occurred within four hours, the DSC will lock out the compressor. The lockout can only be reset by cycling the 24VAC power off and 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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