TABLE 4-2. TROUBLESHOOTING - continued

TM5-4120-347-14

TABLE 4-2. TROUBLESHOOTING (cont.)

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

CONDENSER FAN FAILS TO OPERATE.

Disconnet input power before performing internal electrical troubleshooting. Voltages

used can be lethal.

Step 1.

Check operation of condenser fan motor.

Test motor. Contact direct support maintenance if motor is defective,

Step 2.

Check electrical connections and wiring.

Tighten or replace connectors, or repair or replace damaged wires.

Step 3.

Check fan for binding.

Relieve binding or replace fan.

Step 4.

Check for bad high/low condenser speed fan thermostatic switch, (Refer to paragraph 4-39.)

Replace bad thermostatic switch.

Step 5.

Disconnect condenser fan relay. Actuate primary with 24 volt d-c source, then check continuity

of contacts that should be closed.

Replace bad relay. (Refer to paragraph 4-35.)

INSUFFICIENT COOLING.

Step 1.

Check to see that mode selector switch is properly positioned.

Set switch to COOL.

Step 2.

Check sight-glass liquid level indicator to see that refrigerant is colorless and clear. Yellow,

milky or bubbly refrigerant indicates low level or excessive moisture.

Report condition to direct support maintenance.

Step 3.

Inspect condenser coil for dirt.

Clean coil with 25-30 psi compressed air.

Step 4.

Inspect evaporator return air filter for dirt.

Clean filter. (Refer to paragraph 4-19.)

Step 5.

See whether temperature selector switch is set incorrectly or is no good.

Adjust setting or replace switch, or other corrective action (Refer to paragraph 4-28.)

Step 6.

Check supply air outlet louver to see whether it is bent or stuck in the closed position.

Repair or replace louver. (Refer to paragraph 4-20.)

Step 7.

Observe evaporator fan motor to see whether it is worn or no good.

Report fault to direct support maintenance or replace motor. (Refer to paragraph 4-40.)

Step 8.

Check to see whether evaporator fan is loose or no good,

Tighten setscrew or replace fan. (Refer to paragraph 4-40.)

COMPRESSOR WILL NOT START.

Step 1.

Make sure that compressor or control circuit breakers or selector switch is properly set.

Reset controls properly.

Step 2.

See whether contacts of high-or-low pressure cut-out switch are open.

Reset pressure switches. Report fault to direct support maintenance if condition continued.

Step 3.

Check for loose electrical connections or faulty wiring.

Tighten loose connections. Fix wiring if necessary.

Step 4.

Make continuity check of control circuit to determine whether open circuit exists.

Fix open circuit or replace wire.

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