Mitsubishi Electronics PCA-A24GA service manual SELF-DIAGNOSIS Action Table

10-2. SELF-DIAGNOSIS ACTION TABLE

Note: Refer to the manual of outdoor unit for the details of display such as F, U, and other E.

Error Code	Abnormal point and detection method	Cause	Countermeasure
	Room temperature thermistor (TH1)	1 Defective thermistor	1–3Check resistance value of thermistor.
	1 The unit is in 3-minute resume preven-	characteristics	0: (32˚F)• • • • • • • • • • • 15.0k"
	tion mode if short/open of thermistor is	2 Contact failure of connector	10:(50˚F)• • • • • • • • • • • • • 9.6k"
	detected. Abnormal if the unit does not	(CN20) on the indoor controller	20:(68˚F)• • • • • • • • • • • • • 6.3k"
	reset normally after 3 minutes. (The	board (Insert failure)	30:(86˚F)• • • • • • • • • • • • • 4.3k"
	unit returns to normal operation, if it	3 Breaking of wire or contact	40:(104˚F)• • • • • • • • • • • •3.0k"
	has been reset normally.)	failure of thermistor wiring	If you put force on (draw or bend) the lead wire
	2 Constantly detected during cooling,	4 Defective indoor controller	with measuring resistance value of thermistor
	drying, and heating operation.	board	breaking of wire or contact failure can be detected.
P1	Short: 90:(194˚F) or more		2 Check contact failure of connector (CN20) on
	Open: -40:(-40˚F) or less		the indoor controller board. Refer to 10-6.
			Turn the power on again and check restart
			after inserting connector again.
			4 Check room temperature display on remote
			controller.
			Replace indoor controller board if there is abnor-
			mal difference with actual room temperature.
			Turn the power off, and on again to operate
			after check.
	Pipe temperature thermistor/Liquid	1 Defective thermistor	1–3Check resistance value of thermistor.
	(TH2)	characteristics	For characteristics, refer to (P1) above.
	1 The unit is in 3-minute resume	2 Contact failure of connector	2 Check contact failure of connector (CN21) on
	prevention mode if short/open of	(CN21) on the indoor controller	the indoor controller board. Refer to 10-6.
	thermistor is detected. Abnormal if the	board (Insert failure)	Turn the power on and check restart after
	unit does not reset normally after 3 min-	3 Breaking of wire or contact	inserting connector again.
	utes. (The unit returns to normal opera-	failure of thermistor wiring	4 Check pipe <liquid> temperature with remote
	tion, if it has been reset normally.)	4 Defective refrigerant circuit is	controller in test run mode. If pipe <liquid>
P2	2 Constantly detected during cooling,	causing thermistor temperature	temperature is extremely low (in cooling
	drying, and heating (except defrosting)	of 90:(194˚F) or more or	mode) or high (in heating mode), refrigerant
	operation.	-40:(-40˚F) or less.	circuit may have defect.
	Short: 90:(194˚F) or more	5 Defective indoor controller board	5 Check pipe <liquid> temperature with remote
	Open: -40:(-40˚F) or less		controller in test run mode. If there is extreme
			difference with actual pipe <liquid> temperature,
			replace indoor controller board.
			Turn the power off, and on again to operate
			after check.
	Drain sensor (DS)	1 Defective thermistor	1–3Check resistance value of thermistor.
	1 Suspensive abnormality, if short/open of	characteristics	0: (32˚F)• • • • • • • • • • • • 6.0k"
	thermistor is detected for 30 seconds	2 Contact failure of connector	10:(50˚F)• • • • • • • • • • • • 3.9k"
	continuously.	(CN31) on the indoor controller	20:(68˚F)• • • • • • • • • • • • 2.6k"
	Turn off compressor and indoor fan.	board (Insert failure)	30:(86˚F)• • • • • • • • • • • • 1.8k"
	2 Short/open is detected for 30 seconds con-
		3 Breaking of wire or contact	40:(104˚F)• • • • • • • • • • 1.3k"
	tinuously during suspensive abnormality.	failure of drain sensor wiring	2 Check contact failure of connector (CN31) on
	(The unit returns to normal operation, if
		4 Defective indoor controller board	the indoor controller board. Refer to 10-6.
P4	it has been reset normally.)		Turn the power on again and check restart
	3 Detect the following condition.
			after inserting connector again.
	• During cooling and drying operation
			4 Replace indoor controller board if drain
	• In case that pipe <liquid> temperature
	- room temperature <-10deg		pump operates with the line of drain sensor
	(Except defrosting)		connector CN31-1and 2 is short-circuited,
	• When pipe <liquid> temperature or		and abnormality reappears.
	room temperature is short/open tem-		Turn the power off, and on again to operate
	perature.
			after check.
	• During drain pump operation
	Malfunction of drain pump (DP)	1 Malfunction of drain pump	1 Check if drain pump works.
	1 Suspensive abnormality, if thermistor	2 Defective drain	2 Check drain function.
	of drain sensor heats itself and	Clogged drain pump	3 Check the setting of lead wire of drain sensor
	temperature rises slightly. Turn off	Clogged drain pipe	and check clogs of the filter.
	compressor and indoor fan.	3 Attached drop of water at the	4 Replace indoor controller board if drain
P5	2 Drain pump is abnormal if the condition	drain sensor	pump operates with the line of drain sensor
			connector CN31-1and 2 is short-circuited
	above is detected during suspensive	• Drops of drain trickles from
			and abnormality reappears.
	abnormality.	lead wire.
			Refer to 10-6.
	3 Constantly detected during drain pump	• Clogged filter is causing
	operation.	wave of drain.	Turn the power off, and on again to operate
		4 Defective indoor controller board
			after check.

15