Note. For circuit reference, see DTC P1533 schematic.
Circuit Description
This diagnostic test indicates very low refrigerant pressure or an open low pressure switch/circuit by comparing the A/C request discrete line, which contains the low pressure switch, to the A/C-heater serial data A/C request status. If the A/C request line is low (no voltage present), while the A/C-heater serial data is requesting A/C operation, DTC will set.