Refrigerant Pressure Sensor / Switch: Testing and Inspection

A/C System Servicing

A/C Pressure Switch -F129-, checking






- Switch can be removed without discharging refrigerant circuit.
- Ensure O-ring 10.8 mm x 1.8 mm fits properly in groove.

Switch, checking

- Briefly bridge connections from terminal 1 and 2 with engine running.
- If A/C clutch -N25- switches on, refrigerant circuit is empty.

Pressure switch component between red/black wiring switches coolant fan -V7- to 2nd speed when refrigerant pressure rises.

Evaluating switch operation

To assess if the A/C refrigerant system is working correctly, evaluate A/C pressure switch -F129- operation in conjunction with the following conditions:

- Confirm refrigerant system is fully charged. Insufficient refrigerant pressure (due to refrigerant leak, for example) will switch system off.
- Confirm coolant fan operation. A normal Increase in refrigerant system pressure (due to high ambient temperatures, for example) will result in coolant fan -V7- switching to the next (higher) speed.
- Confirm A/C system shut-off conditions. Excessive refrigerant system pressure (due to a blocked radiator or dirty condenser, for example) will switch system off.