Samsung MC26AC2-07, Service Manual

Page: 39 / 66

Troubleshooting
Samsung Electronics 5-14
Turn off the outdoor power, and then
turn on the power in 5 seconds.
Are the SVA and SVB operate turned off after
operating for about 2 minutes when all
of the indoor units (B & C) are turned off?
• Check and replace the IC02,
and IC03.
• Check and replace the C901.
(1) Does the No14 pin output of the IC04
maintain "High"?
(2) Does the No1 pin output of the IC04
maintain "High"?
Are the Q906 and Q908 in "turn-on" condition?
Are the Q907 and Q909 in "turn-off" condition?
Is the No8 pin output of
the IC04 in "High" condition?
Is the No8 pin output of the
IC04 changed from "High" to "Low"?
The output is changed from "High" to "Low" when the charging to the C904 is completed.
Are the SV-B and SV-C relays (RY73, 74)
turned off when the Q703 and Q704 are
turned off.
Replace the SV-B and SV-C solenoids.
Normal
• Check and replace the IC04.
• Check and replace the resistance
(R902, R904, R905 R906).
(1) Is the No12 pin voltage
of the IC04 DC7V?
(2) Is the No3 pin voltage
of the IC04 DC5V?
Check and replace each transistor.
Is the voltage at both
ends of the C901 0V?
Is the No10 pin voltage
of the IC04 DC7V?
The "High" condition should be maintained for about 2 minutes until a voltage
of above DC7V is charged to the C904.
Is the voltage charged to
the C904 above DC7V?
• Check and replace the D903, D905, D906 and Q703 Q704.
• Check and replace the SVA and SVB solenoid.
• Check and replace the R920 and R921.
• Check and replace the C904.
IC04 Check and replace
• Check and replace the Q703, and Q704.
• Check and replace the relay when necessary.
(Resistance at both ends of the relay: About 400
Ω
)
Do the SVA and SVB operated
when the Q703, and Q704 are turned on?
• Check and replace the IC04.
• Check and replace the R922,
and R924.
5-2-12 When the SV-B and SV-C are malfunctioning with all of the indoor units
(B & C) turned off
1) Checklist :
(1) Are the SVA and SVB under normal operating condition?
(2) Is the voltage of the power normal? (the rating voltage ±10% range)
(3) Are the SV-B (CN75) and SV-C (CN74) connectors in good contact?
(4) Is the resistance at both ends of the solenoid about 1.4k
Ω
?
2) Checking procedures
YES
NO
YES
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
NO NO
YES
YES
YES
YES
NO
DB98_11868A(1)_1 3/3/03 11:17 AM Page 5-4