Scamp L4-135 2.2L (1983)
Low Pressure Sensor / Switch: Testing and Inspection
The Low Pressure Cut-Off Switch, located on the H-valve, is wired in series with the compressor magnetic clutch. It cuts off the electrical power supply
to the clutch when refrigerant pressure drops below the control point of the switch.
Whenever the system is inactivated by the low pressure cut-off switch due to refrigerant loss, the refrigerant oil may have been lost. Therefore, to prevent
damage to the compressor due to operation without sufficient lubrication, the leak must be repaired and the compressor oil level checked before final
charge of the system.
The switch is a sealed, factory calibrated unit. No attempt shall be made to adjust or otherwise repair it. If it is found to be defective it must be replaced.
To Test the Switch (Engine Off)
1. Remove protective rubber boot from low pressure cut-out switch and jump leads together.
2. Press the A/C button.
3. Momentarily turn the ignition switch on (do not crank the en9ine), listen for the compressor clutch engaging.
4. If the clutch does not engage, the cycling clutch switch, wiring or fuse may be defective. Check the clutch circuit and clutch.
5. If clutch engages, connect the manifold gauge set and read evaporator suction pressure. At any pressure of 125kPag (18 PSIG) and above, switch
must actuate clutch.
If the evaporator suction pressure is below 172kPag (25 PSIG), refrigerant system is low on charge or empty due to a leak. For corrective action
refer to refrigerant leak repair procedure.
6. Reconnect boot on switch and perform step number 3.
If the clutch does not engage, discharge the system, replace the switch, and recharge the system.
