Pioneer service manual A Check of outdoor unit, MUH-GA20VB- E1, MUH-GA25VB- E1, MUH-GA35VB- E1

10-3.Trouble criterion of main parts

MUH-GA20VB - E1

MUH-GA25VB - E1

MUH-GA35VB - E1

Part name Check method and criterion Figure

Measure the resistance with a tester. (Part temperature –10°C ~ 40°C)

Defrost		Normal		Abnormal
thermistor
(RT63)		5kΩ ~ 60kΩ		Open or short-circuit
Compressor	Measure the resistance between the terminals with a tester.
(MC)	(Coil wiring temperature –10°C ~ 40°C)						WHT C
INNER
PROTECTOR			Normal				P
MUH-GA20/GA25VB					Abnormal	AUX. MAIN
150i 5°C OPEN		MUH-GA20VB MUH-GA25VB		MUH-GA35VB
						S	RBLK
90i10°C CLOSE
MUH-GA35VB	C-R	3.41~4.18Ω	2.99~3.67Ω	2.46~3.01Ω			RED
					Open or short-circuit
155i 5°C OPEN	C-S	5.41~6.63Ω	4.02~4.92Ω	2.96~3.63Ω
90i10°C CLOSE

Outdoor fan	Measure the resistance between the terminals with a tester.
	(Coil wiring temperature –10°C ~ 40°C)
motor
					MAIN
(MF)
	Color of	Normal		Abnormal	AUX.
	lead wire	MUH-GA20VB MUH-GA25/GA35VB
INNER FUSE					FUSE
145i 2°C	WHT-BLK	323 ~ 396 Ω	189 ~ 233 Ω	Open or short-circuit
CUT OFF	BLK-RED	241 ~ 296 Ω	270 ~ 332 Ω
					BLK RED WHT

10-4. Troubleshooting flow

Compressor and/or outdoor fan motor doesn’t operate.

P INNER PROTECTOR

A Check of outdoor unit

Start
Is the switch SW2- on the		No
			Change the switch SW-2-
indoor electronic control			on the indoor electronic control
P.C. board set to MUH type?			P.C. board to MUH type.
	Yes

Operate the unit in COOL or HEAT mode by pressing the EMERGENCY OPERATION switch. 3-minute time delay works.

Test run operation operates for 30 minutes.

Compressor doesn't operate.

Is there 5V DC between J205 + –J101–

on

No

Is there 230V AC between 4 on the

compressor contactor (52C) and

the deicer P.C. board?

TAB20 on the deicer P.C. board?

Yes

Yes

Is there 230V AC between 3 on the

No

Replace the

Replace the

compressor contactor (52C) and

deicer P.C.

deicer P.C. board.

on the outdoor terminal block (TB1)?

board.

Yes

Check the compressor and compressor

capacitor, and rectify the connecting wire.

Outdoor fan motor

doesn't operate.

No

Is there 230V AC between 4 on the

Is there 5V DC between J205 + –J101– on

compressor contactor (52C) and

the deicer P.C. board?

TAB 20 on the deicer P.C. board?

Yes

Yes

Check the outdoor fan motor

Replace the

and rectify the connecting

deicer P.C. board.

wire.

No

No

Rectify the indoor and outdoor connecting wire.

No

Is there 230V AC between –

on the outdoor terminal block (TB1)?

Yes

Rectify the connecting wire.

Rectify the indoor and outdoor connecting wire.

No

Is there 230V AC between – on the outdoor terminal block (TB1)?

Yes

Rectify the connecting wire.

24