TM-9-2320-280-34 HMMWV Direct Support & General Support Maintenance Manual Download
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TM 9-2320-280-34 Table 2-3. Air Conditioning Troubleshooting (Cont’d) MALFUNCTION TEST OR INSPECTION f. Check for High Side Restriction Step 1. Perform malfunction 1a, steps 1 through 4. Step 2. Check low side of manifold gauge for low reading and high side for normal to high reading (table 2-2). If discharge (evaporator) air is cool and high side refrigerant lines are cold, wet, or frosted, remove liquid line (para. 14-17), flush line (para. 14-17), and replace dryer bottle (para. 14-19). NOTE If blockage then occurs in liquid lines, condenser, receiver-drier, or expansion valve, frost may build up just beyond point of restriction. g. Check Condenser Step 1. Perform malfunction 1a, steps 1 through 4. Step 2. Check low side of manifold gauge for normal or high reading and high side for high reading (tabl e 2-2). If discharge (evaporator) air is warm, liquid line is hot, air flow through condenser is restricted, bubbles are seen in sight glass, then clean condenser exterior, if dirty. If condenser fans are inoperative, refer to electrical system troubleshooting (TM 9-2320-280-20) Flush condenser (para. 14-17) or replace condenser (para. 14-24), if damaged. h. Check for Overcharged System Step 1. Perform malfunction 1a, steps 1 through 4. Step 2. Check low side of manifold gauge for normal to high readin g and high side for high reading (table 2-2). If system runs continuously, compressor is noisy on start-up, discharge (evaporator) air is warm, a partial system discharge is required, continue to step 3. Step 3. Insert center hose of manifold gauge set in a catch bottle or can. NOTE Do not allow refrigerant, R-12, to escape too quickly. Refrigerant oil will escape. Step 4. Turn low pressure gauge valve and high pressure gauge valve counterclockwise slightly to permit refrigerant to slowly escape through center hose until correct pressure and high side pressure are obtained. END OF TESTING! 2. INTERMITTENT COOLING Check air-conditioner output for temperature variation. If air is intermittently warm and cold, perform the following: Step 1. Check for air or moisture in system by performing malfunction lb. Step 2. Ensure temperature sensing probe is inserted properly in the evaporator fins near the outlet (para. 14-14). Step 3. Perform mechanical troubleshooting malfunction 9. Step 4. Check sight glass reading for oil streaks, indicating too much oil in system. Step 5. If oil is found in system, flush system (para. 14-17), replace dryer bottle (para. 14-19), and change oil (para. 14-17). END OF TESTING! 2-23