Mitsubishi Electric PUHY-HP120TNU-A, Service Handbook

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[8-12 Parts Replacement Instructions ]
HWE18240_GB chapter 8 -
55
8 Troubleshooting Based on Observed Symptoms
(7) Remove the solenoid valve and the LEV assembly at the front of the four-way valve at the brazed sections to ensure good
visibility of the four-way valve.
Either remove or protect the solenoid valve coil, TH and LEV wirings, pipe cover, and plastic components to keep them
from being damaged by the torch flame. (Remove the components by removing the braze from the six areas shown in
Figure 7.)
Replacement procedure for four-way valve (21S4a)
(8A) Remove the pipe covers adjacent to four-way valve (21S4a). (See Figure 8.)
(9A) Remove the sheet metal screwed to the base below four-way valve (21S4a) by unscrewing the two screws.
(See Figure 9.)
Figure 7
Remove the pipe cover adjacent to four-way valve coil A.
*Save the pipe cover for later use.
Figure 8
Figure 9
Solenoid valve/LEV assembly
Remove the braze from the six areas circled in the figure to remove
the pipes.
*Save the removed pipes for later use.
(6) Remove the plastic cover and the coil holding the four-way valve. (See Figure 6.)
Figure 6
Four-way valve coil A
Four-way valve coil B
*Notes on replacing refrigerant circuit components (check valve, four-way valve, solenoid valve, and LEV)
Be sure to perform non-oxidized brazing.
Before heating the pipes, wrap the refrigerant circuit components with a wet towel to keep the temperature of the
components from rising above 120°C.
After brazing is done, check that the brazing is done properly and check for leaks before vacuum-drying the pipes.
Direct the brazing torch flame away from the wiring and sheet metals inside the unit not to damage them.
Wet felt sheets listed below (or its equivalent), and place them around the areas to be brazed to protect the heat
exchanger, pipes, and pipe covers from being damaged from the brazing torch flame.
Recommended felt sheets: Spatter felt 50CF-11 (5t x 1 m x 1 m) by TRUSCO Nakayama
Felt sheets that meet the JIS standard (JIS A 1323 type A "Flame retardant testing method for spark droplets of
welding and gas cutting on fabric sheets in construction works")