c. Repair. Repair of the heating elements consists of replacement.
d. Installation. Install heating elements as follows:
(1) Position heating elements in the heating element holddown brackets and install all mounting hardware.
(2) Tighten all heating element holddown clamps.
(3) Reinstall complete heating assembly and secure with attaching hardware.
(4) Connect all wires to their proper location and remove tags.
(5) Connect interconnecting refrigerant lines.
(6) Secure protective cover for piping to the shelter wall with self-tapping screws.
Support air conditioner sections while installing bolts.
(7) Position inner sections on the inside front wall and secure with mounting bolts.
(8) Install interconnecting liquid lines between interior and exterior sections of the air conditioner.
(9) Install all covers to air conditioner sections.
(10) Install the hose duct which connects the air intake grill to the evaporator section.
(11) Install the humidifier as described in paragraph 4-31.
(12) Install the three MS electrical connectors on the right side of the air conditioner evaporator section and turn on
electrical power to the air conditioner.
(13) Attach charging line to suction service valve port.
(14) Backseat the discharge service valve and remove the cap from the port.
(15) Open the suction service valve so both port and compressor are open.
(16) Open the valve on the refrigerant drum and build 30 pounds pressure in system.
(17) Test for leaks using halide detector torch.
(18) Release pressure in system and replace cap on discharge service valve port.
(19) Using an evacuator, pull a 20 to 25 inch vacuum on the refrigerant system, attaching the vacuum line to suction
service valve port. Purge with gas from freon drum and again pull vacuum.
(20) When 20 to 25 inch vacuum is reached, backseat the suction service valve.
(21) Remove the evacuator vacuum line.
The R-12 drum for recharging should be equipped with a large capacity drier.
(22) Attach a charging line to the R-12 drum (see fig. 12-1).
(23) Weigh the drum so that 13 pounds can be measured into the system.
(24) Attach charging line to unit. Do not tighten.
(a) If charging line is attached to suction service valve, be sure drum is upright so only gas will be drawn off.
(b) If charging line is attached to charging valve in condenser fan section, close valve at condenser outlet, and
invert drum so only liquid will be drawn off.
(25) Open R-12 drum valve slightly and then close, to purge air from charging line. Tighten charging line on service
(26) Open valve on R-12 drum about 2 turns.
(27) Open the system charging valve about 2 turns and allow pressure to equalize.
(28) Start unit and run until 13 pounds of R-12 are added.
(29) Backseat suction service valve (or close charging valve).
(30) Remove charging line from valve.
(31) Replace cap on valve.
12-2. Terminal Relay Box
The terminal relay box (see fig. 12-5), located in the evaporator section of the air conditioner, contains two power
relays and one magnetic contactor which are used in the heating control circuit.