RAM 1500 Van V8-5.2L VIN Y (1999)
Expansion Valve: Testing and Inspection
Front A/C (Only)
FRONT A/C (only)
These tests must be made at an ambient temperature of 21 to 29° C (70 to 85° F).
Testing
1. Attach a manifold gauge set. Close the vehicle doors and windows, start the engine, and hold the engine speed at 1000 rpm. Set the heater-A/C
mode control switch knob in the recirculation mode (Max A/C) position, the temperature control knob in the full hot position, and the blower
motor switch in the highest speed position. Disconnect and plug the vacuum harness connector at the water valve in the engine compartment.
Unplug the fin sensing cycling clutch switch wire harness connector.
2. Operate the air conditioning system for at least five minutes to stabilize the system, and to provide sufficient reheat to load the evaporator. The
discharge pressure (high side) at the service port should reach 966 to 1656 kPa (140 to 240 psi). If this discharge pressure cannot be obtained,
check the refrigerant system charge. See Refrigerant System Charging.
See: Service and Repair/Refrigerant System Charge
WARNING: EXTREME CARE MUST BE USED WHEN HANDLING LIQUID CARBON DIOXIDE (CO2), AS SKIN INJURY CAN
OCCUR. PROTECTIVE GLOVES SHOULD BE WORN.
3. Apply liquid carbon dioxide (CO2) to the expansion valve control head (completely cover the head) for a minimum of thirty seconds. Observe the
manifold gauge set. The suction pressure (low side) must drop to below 50 kPa (7.25 psi). If this reading is not obtained, the expansion valve is
faulty and must be replaced.
4. Remove the liquid carbon dioxide (CO2) from the control head. Observe the manifold gauge set. The suction pressure (low side) must increase to
a minimum of 262 kPa (38 psi), and then stabilize to a pressure of 172 to 240 kPa (25 to 35 psi). If these readings are not obtained, the expansion
valve is faulty and must be replaced.
5. Set the engine idle speed at 1000 rpm and the blower motor switch in the highest speed position. The suction pressure (low side) should be 138 to
207 kPa (20 to 30 psi). If the discharge pressure (high side) is higher than 1656 kPa (240 psi), check for a restricted discharge line. Also check
the engine cooling system for overheating, air trapped in the system, or a faulty fan drive. If the discharge pressure (high side) is less than 966 kPa
(140 psi), check for a faulty compressor.
