Diplomat V8-318 5.2L VIN K 2-bbl (1982)
H-Valve: Testing and Inspection
Fig. 28 Disconnecting in-car sensor
Test should be performed at ambient temperature of 70 - 85 °F.
1. Close vehicle windows and run engine at 1000 RPM. Turn A/C controls to A/C Max, blower to High, and temperature control lever to full reheat.
Bypass clutch cycling and low pressure cutoff switches. On vehicles equipped with semi-automatic temperature control, lock blend door in full
reheat position by disconnecting in-car sensor from harness connector and switch on system.
2. Disconnect and plug water valve vacuum hose in engine compartment.
3. Run system for at least 5 minutes to obtain partial stabilization and sufficient reheat to load system. Pressure at discharge service port should reach
115-240 PSIG on car models, 140-240 PSIG on trucks and vans. If this pressure cannot be obtained, check system charge level.
4. Spray H-valve control head with liquid Freon for 10 to 15 seconds. Evaporator suction pressure must reduce below 15 inches Hg of vacuum. If
not, H-valve is stuck open and must be replaced. Stop spraying Freon and observe evaporator suction pressure which should increase (to at least
38 PSIG on trucks and vans) and then stabilize at 20-35 PSIG on cars, 25-35 PSIG on trucks and vans. An H-valve that does not respond in this
manner is stuck closed and should be replaced.