Carrier Understanding Diagnostic LEDs and Troubleshooting for 50EK and 50EJ Air Conditioners

Diagnostic LEDs (Light-Emitting Diodes) Ð There are 3 LEDs (red, yellow, and green) on the lower right hand side of the control board. The red light is used to check unit operation and alarms. A constant pulse is normal unit operation. A series of quick blinks indicates an alarm. Refer

to Table 20 below for a description of alarms. The yellow LED blinks during transmission with the CCN (Carrier Com- fort Network). The green LED blinks during transmission with the expansion board.

Table 20 Ð Control Board LED Alarms

	LED	ERROR	DESCRIPTION	TROUBLESHOOTING
	BLINKS	CODE		COMMENTS
	1		Normal Operation	The expansion board and control board ¯ash the red LED in one-
				second intervals when the board is operating properly.
	2	HF-13	Compressor 1 Safety	The high or low pressure safety switch for compressor no. 1 has
				opened for 3 seconds. The error will be cleared and compressor
				no. 1 will be allowed to turn on in 15 minutes. If the safeties have
				been tripped 3 times in 90 minutes, compressor no. 1 will be
				locked out until the control board has been manually reset.
	3	HF-14	Compressor 2 Safety	The high or low pressure safety switch for compressor no. 2 has
				opened for 3 seconds. The error will be cleared and compressor
				no. 2 will be allowed to turn on in 15 minutes. If the safeties have
				been tripped 3 times in 90 minutes, compressor no. 2 will be
				locked out until the control board has been manually reset.
	4	HF-15	Thermostat Failure	The thermostat is calling for both heating and cooling at the
				same time. The unit will operate on a ®rst call basis and will auto-
				matically reset.
	5	HF-05	SAT Thermistor Failure	The supply-air temperature (SAT) sensor has failed. First check for
				wiring errors, then replace sensor.
	6	HF-06	OAT Thermistor Failure	The outside-air temperature (OAT) sensor has failed. First check
				for wiring errors, then replace sensor.
	7	HF-03	Space Temp. Sen. Failure	The space temperature sensor has failed. First check for wiring
				errors, then replace sensor.
	8	HF-12	RAT Thermistor Failure	The return-air temperature (RAT) sensor has failed. Ensure that
				the unit is a VAV unit. If NOT a VAV unit set DIP switch position 1
				to the closed position and reset power. Then check for wiring
				errors. Finally, replace sensor.
	9	SE-05	Loss of Communications	Communications between the expansion board and the control
			with Expansion board	board have been interrupted. Ensure that an expansion board
				is installed and wired using the wire harness supplied with the
				expansion module. If an expansion board is not used ensure that
				DIP switch position 3 is in the closed position, and reset power.
	10	HF-16	Control Board Failure	Generated when hardware has failed on control board. Replace
				the control board.
	11	HF-17	Expansion Board Failure	Generated when hardware has failed on the expansion board.
				Replace the expansion board.
	LEGEND
DIP	Ð Dual In-Line Package
LED Ð Light-Emitting Diode
VAV	Ð Variable Air Volume

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