Mitsubishi Electric HP120TNU-A Service Handbook page 308

[8-13 Parts Replacement Instructions ]
8-13-3 Four-way Valve Replacement Procedure (Applicable to four-way valves 21S4a
and 21S4b)
Explained below is the procedure for replacing four-way valve (21S4a) (on the left when seen from the front of the unit) and
four-way valve (21S4b) (on the right when seen from the front of the unit).
Secure sufficient work space before starting maintenance work. (See 8-13-1 Ensuring Maintenance Space (Preparation for the
Maintenance of Refrigerant Circuit Parts).)
(1) Remove the top compressor cover by unscrewing the three screws. (See Figure 1.)
Remove the compressor cover by unhooking the hooks on the back.
(2) Remove the front compressor cover by unscrewing the four screws. (See Figure 2.)
(3) Cut the two cable ties holding TH4 and TH15, and remove the wiring from the rubber bush on the left compressor cover.
(See Figure 3.)
(4) Remove the left compressor cover by unscrewing the two screws. (See Figure 4.)
Compressor cover (top)
Figure 1
Figure 4
(5) Remove the coils, coil covers, pipe covers, and adjacent wiring of the four-way valve and LEV. (See Figures 5-1 through
5-3.)
Four-way valve coil (21S4a)
Figure 5-1
(6) Cut the band on the pipe cover and the rubber spacer on the heat-exchanger side to remove them. (See Figure 6.)
Figure 6
HWE18220_GB
Compressor cover (front)
Figure 2
Four-way valve coil (21S4b)
LEV coil (LEV2d)
Figure 5-2
Remove the pipe cover adjacent to the brazed section of the
heat exchanger.
*Save the pipe cover for later use.
Rubber spacer band
TH4
Rubber bush
TH15
Compressor cover (left)
Figure 3
Figure 5-3
Remove the five pipe covers adjacent to the four-way valves.
*Save the pipe covers for later use.
Cable tie
67
chapter 8 -