W/ Fixed Displacement Compressor

Review General Information Safety Precautions Before proceeding with this operation. This test requires the use of a Charging Station or Manifold Gauge Set.

Test must be made at ambient temperature of 21° to 27°C (70° to 85°F).

After performing all previously mentioned test, conduct the H-valve test as follows:
1. Close the windows and operate the engine at 1000 rpm. Set air conditioning controls on PANEL or A/C, High blower, temperature control in full heat position. Locate and remove both vacuum lines at the recirculating air door actuator and install the light green line where the dark green line had been. Electrically by-pass the clutch cycling switch using a jumper wire across the terminals.
2. Operate the system for at least (5) minutes in order to obtain partial stabilization and sufficient heat to load the system. Pressure at the discharge service port should reach 965 to 1655kPag (140-240 psig). If head pressure to 965 to 1655kPag (140-240 psig) cannot be obtained, check system charge level.

Expansion Valve:

3. Put crushed dry ice on control head of H-valve assembly (completely cover head) for a minimum of 30 seconds.

WARNING: ALWAYS WEAR PROTECTIVE GLOVES WHEN HANDLING DRY ICE TO PROTECT HANDS FROM INJURY.

Compressor suction pressure must drop to below -50kPag (15" of vacuum). If the condition is not met, the H-valve is stuck open and should be replaced. Remove dry ice and watch compressor suction pressure; it should stabilize at 140-240kPag (20-35 psig) after rising to a higher pressure temporarily. Any H-valve which does not produce this response is stuck closed and should be replaced.
4. Set engine speed at 1000 rpm and also on high blower. The evaporator suction pressure should be in the range of 138 to 207kPag (20-30 psig). If compressor discharge is higher than 1655kPag (240 psig) check for restricted discharge line, radiator overheating, air in refrigerant system or for electric fan not operating.
5. Connect the electrical wires, water valve, vacuum hose.