Table 4-1. TROUBLESHOOTING (cont.)

TM 5-4120-359-14

Table 4-1. TROUBLESHOOTING (cont.)

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

WARNING

The following test must be conducted with the power on.

Exercise extreme

caution.

(b)

Apply power.

(c)

Measure voltage between J4 connector contacts A and H.

(d)

If 25 to 31 Vdc is not indicated check rectifier CR1.

(e)

Remove electrical module assembly (evaporator) top cover.

(f)

Measure rectifier voltage output across pos (+) to neg (-) terminals.

(g)

If 25 to 31 Vdc is not indicated, check ac input to rectifier.

(h)

If 27 to 33 Vac is indicated.

Replace rectifier CR1.

(i) If 27 to 33 Vac is not indicated, turn power off and check individual wire leads.

Replace or repair as indicated.

Step 13.

Check remote control assembly.

(a) Measure resistance between connector J14 pins in accordance with table in paragraph 4-103.b.

(b) If resistances are not as indicated on table, use electrical schematic (figure 4-4) or wiring diagram

(figure 4-3) to locate defect.

Repair or replace as indicated.

INSUFFICIENT COOLING

Step 1.

Check to see that MODE SELECTOR SWITCH is properly positioned.

Set switch to COOL.

Step 2.

Check to see that TEMPERATURE CONTROL is set to COOLER position.

Set TEMPERATURE CONTROL to COOLER position.

Step 3.

Inspect fresh and return air filters, for dirt or blockage.

Clean filter/remove blockage.

Step 4.

Check that condenser air is not blocked.

Fabric condenser cover must be rolled up and tied. Remove any obstruction from condenser

inlet or discharge.

Step 5.

Check that high pressure cutout, reset is not tripped.

Press in to reset.

Step 6.

Check fresh air inlet for heat source.

Move all heat sources, over 50 F (10 C) above outside ambient, at least 10 feet from fresh

air inlet.

Step 7.

After 15 minutes of operation in COOL mode with TEMPERATURE CONTROL set to COOLER

position, check sight glass. Refrigerant should be clear and center indicator should be green.

If refrigerant is milky or many bubbles are seen, leak test, repair and recharge as indicated.

(See paragraph 4-8.)

If center indicator is yellow evacuate and recharge.

(See

paragraph 4-9.)

Step 8.

Check refrigerant system.

(a) Measure ambient outside temperature.

(b) Apply power.

15 minutes.

4-7