3-3-8 When the 4 way valve (A,B) is not operating
1)Inspection items
(1)Are the 4 way valve A and B under the operating conditions?
(When the COMP A (4 way valve A ) and COMP B (4 way valve B) are on during the heating operating)
(2)Is the power voltage normal?
(3)Is the connecting of 4 way valve A (CN 75) and B (CN 76) good?
2) Inspection sequence
Put off the outdoor unit power and put it on again after 5 seconds.
Select the heating operation of A(B) room by the remote controller.
Has 3 minutes passed after selection of A(B) room heating?
YES
Is the 4 way valve A(B) on?
NO
Is the voltage shown across the 4 way valve A(B) connector
(CN 75, CN 76) ?
NO
Is the pin no 47(46) of IC 04 ( MICOM) at high (DC 5V) ?
NO
Is the 4 way valve A (B) under operating conditions?
NO
Normal
NO
YES
YES
YES
YES
Keep 4 way valve off.
Normal
Defect of RY 76 (RY 77) contact and coil
→Replace the Relay
Defect of IC 06 (IC 07 ) output → Replace
Defect of IC 04(MICOM) - replace the IC 04
or PCB ass’y
*4 way valve operating conditions
(1)During the defrost control, put the 4 way valve A(B) off.
(2)During the heating operation put the 4 way valve A(B) on.
(3)The changeover of heating to cooling : put the 4 way valve off immediately (in case of B and C room).
(4)The changeover of cooling to heating : it is on after 170 seconds delay.
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