Samsung MH026FPEA Training Manual page 102

8-3-8 When the 4-Way valve is not operating
1. Checklist :
1) Are the 4-Way valve under the operating conditions?
When the Comp. is on during the heating operating.
2) Is the power voltage normal?
3) Is the connecting of 4-Way valve good?
2. Troubleshooting procedure
Put off the outdoor unit power and put it on again after 5 seconds.
Select the heating operation of room by the remote control.
Has 3 minutes passed after selection of room heating?
Is the voltage shown across the 4-Way valve connector
Is the pin #47(46) of IC04 (MICOM) at high (DC 5V) ?
Is the 4-Way valve under operating conditions?
✳ 4-Way valve operating conditions
(1) During the defrost control, put the 4-Way valve off.
(2) During the heating operation put the 4-Way valve 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.
Samsung Electronics
Yes
Is the 4-Way valve on?
No
(CN75, CN76) ?
No
No
No
Normal
No
Keep 4-Way valve off.
Yes
Normal
Yes
Defect of RY76 (RY77) contact and coil
→ Replace the Relay
Yes
Defect of IC06 (IC07) output
→ Replace
Yes
Defect of IC04(MICOM) -
replace the IC04 or PCB ass'y
Troubleshooting
101