TEST - TM-9-4120-425-14-P0162

TM 9-4120-425-14&P

JUNCTION BOX ASSEMBLY UNIT MAINTENANCE - Continued

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TEST Continued

Compressor Motor and Condenser Motors Relay (K1), Heaters Relay (K2), Evaporator Fan Motor

Relay (K3)

Tag and disconnect wire leads.

Use a multimeter. Set on the lowest ohm to check continuity between terminals L1 to T1, L2 to T2 and L3 to T3. All

contacts should be open. If there is continuity, replace the relay. See WP 0122-00.

Check continuity between terminals A and B. If there is no continuity, the coil is open. Replace the relay.

Apply 24 V ac across terminals A and B and repeat continuity checks between terminals L1 to T1, L2 to T2 and L3

to T3. All three contacts should be closed. If there is no continuity, replace the relay.

Thermostat (13)

Remove and tag thermostat (13) wire from terminal board TB3-8.

Apply a 24 5 V ac power source to the thermostat wire removed from TB3-8 and to terminal board TB3-2.

With temperature selector switch (S2) in "COOLER" position (full counterclock) and mode selector switch (S1) in

"COOL" position, warm the thermostat probe (4) by holding in hand.

Check voltage (24 V ac) between terminal board TB3-2 and TB3-7.

Replace if NO voltage.

With temperature selector switch (S2) in "WARMER" position (full clockwise) and mode selector switch (S1) in

"HEAT" position cool the thermostat probe (4) in ice bath.

Check voltage (24 V ac) between terminal board TB3-2 and TB3-3.

Replace if NO voltage.

REPAIR

Junction Box

Repair or straighten sheet metal parts.

REPLACEMENT

NOTE

Ensure wire leads are tagged before disconnecting.

Compressor Motor and Condenser Motors Relay (K1)(20), Heaters Relay (K2)(20), Evaporator and

Condenser Motor Relay (K3)(20)

Remove the relays (K1-K3) (20) from the junction box by removing four screws (19) from each relay.

Install replacement relays (K1-K3) on the junction box chassis (36).

Secure each relay (20) to junction box chassis (36) with four screws (19).

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