Circuit Description
This diagnostic detects an over temperature/over pressure condition
in the A/C system. The DTC will be set if the high pressure switch disables
the A/C clutch and the high side temperature is above a threshold. Under
extremely hot ambient conditions a rapid cycling situation could occur
as this DTC is set and cleared. To protect the A/C system, if this DTC
continues to set and clear, a lower high side temperature will be used
to clear the DTC. If after this occurs a rapid cycling condition is still
detected a third, lower temperature is used to clear the malfunction DTC
and re-enable the A/C clutch.
Conditions for Running the DTC
DTC P1535 not set.
Conditions for Setting the DTC
| • | DTC P1542 is not current. |
| • | A/C disabled by high pressure switch. |
| • | High side temperature 87°C (189°F) or higher. |
| • | A/C disabled by high pressure switch |
| • | If State 0 -high side temperature is 82°C (180°F)
or higher, |
| • | If State 1 -high side temperature is 79°C (174°F)
or higher. |
| • | If State 2 -high side temperature is 76°C (169°F)
or higher. |
| - | State 1 occurs when state 0 is active and DTC P1542 has set 10
times or more in 30 seconds. |
| - | State 2 occurs when the state 1 is active and DTC P1542 has set
more than 15 times in 30 seconds. The DTC P1542 counter and timer will be
reset to 0 on any state transition. |
| - | After each power up, state 0 is the initial active state. If,
during the ignition cycle, the state should progress to state 2, it is to
remain in state 2 for the duration of the ignition cycle. |
Action Taken When the DTC Sets
Disengage the A/C compressor.
| • | The Malfunction Indicator Lamp (MIL) will not illuminate. |
| • | The PCM will command a message to be displayed. |
| • | The PCM may record operating conditions at the time the diagnostic
fails. This information will be stored in the Failure Records. |
Conditions for Clearing the Message/DTC
| • | The PCM will turn the message OFF after one run and pass of the
diagnostic test. |
| • | 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. |
Diagnostic Aids
This DTC is used for system protection during a high temperature /
pressure condition. This condition could occur normally if sufficient cooling
of the A/C system cannot occur due to high ambient temperature.
Test Description
The numbers below refer to the step numbers on the Diagnostic Table.
-
If the outside temperature was not excessive when the DTC set, than
the A/C system experienced an overheating / high pressure condition and should
be diagnosed in the HVAC section.
