Manual Air Conditioning

Test must be performed at ambient temperature of 70 - 85 °F.

1. Install manifold gauge set.
2. Close windows and run engine at 1000 RPM. Set controls for Max A/C, blower on High, and temperature control lever in full heat position.
3. By-pass low pressure cut-out switch and clutch cycling switch. Disconnect and plug vacuum hose to water valve.
4. Run system for at least 5 minutes to obtain partial stabilization and sufficient heat load.
5. Pressure at discharge service port should reach 140-240 psig. If pressure cannot be attained, check system charge level.
6. Spray H-valve control head with liquid Freon for 10 seconds. Compressor suction pressure should drop to below 15 inches Hg of vacuum. If condition is not met, H-valve is stuck open and must be replaced. Discontinue spraying Freon and observe compressor suction pressure which should stabilize at 20-35 psig after temporarily rising to a higher pressure. If H-valve does not respond in this manner, it is stuck closed and must be replaced.
7. Adjust engine speed to 1000 RPM and set blower to High. Evaporator suction pressure should be about 20-30 psig. If compressor discharge pressure is higher than 240 psig, check for the following: restricted discharge line, air in cooling system, overheating radiator, or inoperative electric cooling fan.
8. Reconnect wires, water valve vacuum hose and set temperature control to Cool.