A/C Pressure Switch, Checking

A/C Pressure Switch, Checking

Visual check: Ensure that O-ring (color: red) 10.8mm x 1.8mm is seated in groove.

Switch function between contacts -T4a/1- and -T4a/2- (at connector housing) switches A/C Clutch (N25) off whenever:

• excessive refrigerant circuit pressure is present (e.g.: insufficient air flow over condenser or if system is overcharged)

• insufficient refrigerant circuit pressure is present (e.g.: when refrigerant has leaked out).

Switch function between contacts -T4a/3- and -T4a/4- (at connector housing) switches Coolant Fan (V7) to 2nd speed when refrigerant pressure rises.

Switching conditions





• Contacts - 1 - and - 2 - open below 1.2 bar (17.4 psi) and closed above 2.4 bar (34.8 psi) switching threshold

• Contacts- 1 - and - 2 - open above 32 bar (464 psi) and closed below 24 bar (348 psi) switching threshold

• Contacts - 3 - and - 4 - closed above 16 bar (232 psi) and open below 12.5 bar (181.2 psi) switching threshold

Switch function, checking





- Bridge contacts - 1 - and - 2 - with engine running. If A/C Clutch (N25) switches on, refrigerant system may be empty => [ A/C Refrigerant System, Testing with Pressure Gauges ] A/C Refrigerant System, Testing With Pressure Gauges.