P1540

Circuit Description
This diagnostic detects an over pressure condition in the Air Conditioning (A/C) system. The DTC is set if the A/C high pressure switch, opens at 430 psi, disables the A/C clutch at least 10 time with high side temperature below a threshold. This is designed to detect blockages in the A/C system. When the DTC is set, the A/C clutch will be disabled for the ignition cycle.

Conditions for Running the DTC
A/C is ON.

Conditions for Setting the DTC
A/C clutch disabled 10 time by the A/C high pressure switch with the A/C high side temperature less than 87°C (109°F).

Action Taken When the DTC Sets
Disengage the A/C compressor for the ignition cycle.
^ The Malfunction Indicator Lamp (MIL) will not illuminate.
^ No message will be displayed.

Conditions for Clearing the DTC
^ A History DTC will clear after forty consecutive warm-up cycles with no failures of any non-emission related diagnostic test.
^ A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail.
^ Use a scan tool to clear DTCs.
^ Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended.

Diagnostic Aids
Use the Failure Rec. on the scan tool and note the conditions under which the DTC set. If A/C High Side Temp. was close to 87°C (189°F) then a high pressure condition probably occurred, if A/C High Side Temp. was low than an intermittent open circuit or switch probably set this DTC.

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
2. Checking if fault is present.
3. Checking if fault is pressure or switch I/circuit problem.