REFRIGERATION UNIT TEST

TM 10-4110-262-13&P

0028 00

DIRECT SUPPORT MAINTENANCE

ADVANCED DESIGN REFRIGERATOR, 300 CUBIC FOOT (ADR-300)

4110-01-465-4158 / 4110-01-465-4564

REFRIGERATION UNIT

TEST

INITIAL SETUP

References

Tools and special tools

None

Tool Kit, Refrigeration Service

(WP 0051 00, Table 2, Item 5)

Equipment Conditions

Multimeter (WP 0051 00, Table 2, Item 2)

ADR-300 set up and connected to a power

source (See WP 0005 00 for set-up procedures).

Materials and Parts

None

Personnel Required

HVAC Technician (MOS 52C, AFSC 3E1x1) (1)

Potential Operating Problems

Use the following information to troubleshoot your unit. If the desired container temperature cannot be

obtained, any of the following may be indicated:

1. Excessive Heat Load - An excessive heat load on the system will be caused by too many, or

excessively long door openings. Excessive heat loads will also be caused by a loose door, loose

body panels, warm loads, and poor insulation.

2. Dirt On Coils - Dirt on the condenser or evaporator coils acts as an insulator, reducing the capacity

of the unit.

3. Shortage of Refrigerant - Shortage of refrigerant reduces the capacity of the unit. Find and remedy

the cause of the shortage and recharge the system. DO NOT operate the unit if there is an indication

of low charge. DO NOT operate below 30 F (-1 C) box temperature if the refrigerant level is low as

indicated in the liquid line sight glass.

4. Faulty Expansion Valve Adjustment - High superheat settings will starve the evaporator causing

low suction pressure. Low superheat settings will flood the coil causing high suction pressure. The

superheat setting should be adjusted ONLY by a trained refrigeration service technician. The

superheat setting is 6 F (4.4 C) at 0 F (-18 C) box temperature.

5. Excessive Oil - Too much compressor oil in the system may result in lower than normal suction

pressure as well as lowered capacity.

6. Moisture in the System - Symptom: Expansion valve freeze-up will not allow refrigerant circulation.

Usually this can be checked by warming the expansion valve with either a hand or hot towels to see if

the valve opens. Evacuate the system. Install a new dehydrator.

7. Expansion Valve Loses its Charge - If the expansion valve loses its charge, the valve will close

causing the system to go into a vacuum. Replace the valve.

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