Powertrain, generic · Hybrid propulsion

P0D77 A/C Compressor Control Module Output Driver Temperature Sensor Circuit High

Check engine lightOn
EmissionsNot relevant
Drive cycleRequired
Limp modeNo

P0D77 is the high-signal circuit code of the output driver (IGBT) temperature sensor in the electric A/C compressor. As with an NTC sensor, the high signal shows up as an impossibly cold temperature: GM sets it when the IGBT reading is at or below −40 °C, in all Volt and ELR tables from 2011 to 2019. The first-generation Volt needs 30 of 60 samples at 50 ms and evaluates only with outside air above −7 °C; the 2016 Volt counts 40 of 50 samples at 100 ms, the 2019 Volt 4 of 5 s, with the compressor reporting the fault over GMLAN. Type B, MIL after two trips. Without a valid power-stage temperature the compressor cannot protect itself and is normally switched off. Likely an open sensor path on the inverter board; hot-side code P0D78.

Likely causes

Open circuit in the IGBT temperature sensor path
Cracked solder joint on the inverter board
Faulty value transmission to the host controller

Symptoms

  • Check engine light after two trips
  • Air conditioning switched off

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–2,500
Time1–5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

ac compressor cm output driver temp sensorac compressor module

Related codes

P0D78P0D76P0D75P0D79P0D72

References: gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com.