Cooldown Test Too Cold To Start
NOTE:
Evaporator temperature must be greater than 55°F (12.7°C) and the work area ambient temperature must be more than 70°F (21.1°C) to test A/C system performance.
NOTE:
After making any repairs, perform BODY VERIFICATION TEST under VERIFICATION TESTS.
- Start engine. Ensure A/C button on HVAC control panel is off. Place blower speed selector to highest position. Allow blower to run for 5 minutes to ensure evaporator temperature is greater than 55°F (12.7°C). Using scan tool, activate A/C cool down test. See A/C COOL DOWN TEST under SYSTEM TESTS in MANUAL A/C-HEATER SYSTEMS article in HVAC. If scan tool displays COOL DOWN TEST TOO COLD TO START, go to next step. If DTC/fault message is not displayed, perform additional testing as necessary.
- If scan tool displays any additional DTCs, return to DTC/fault code list. Perform appropriate test procedure for DTC(s) displayed. See DIAGNOSTIC TROUBLE CODE IDENTIFICATION table. After repair is complete, use scan tool to erase DTCs. Cycle ignition switch off, then on again. Using scan tool, perform A/C cool down test. See A/C COOL DOWN TEST under SYSTEM TESTS in MANUAL A/C-HEATER SYSTEMS article in HVAC.
- Turn ignition switch to ON position. Using scan tool, check for any Powertrain Control Module (PCM) DTCs present. If any PCM DTCs are present, go to appropriate test procedure. See SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. If no PCM DTCs exist, perform A/C system cool down test or diagnose concern with A/C system performance. See A/C COOL DOWN TEST under SYSTEM TESTS in MANUAL A/C-HEATER SYSTEMS article in HVAC. If PCM DTCs are not present, go to next step.
- Turn ignition switch to OFF position. Disconnect evaporator temperature sensor. See Fig 1. Turn ignition switch to ON position. Using scan tool, select SENSOR DISPLAY, then EVAPORATOR TEMPERATURE SENSOR. If reading is 4.9 volts or greater, go to next step. If reading is less than 4.9 volts, go to step 6.
- Turn ignition switch to OFF position. Connect a jumper wire between evaporator temperature sensor signal terminal (Dark Blue/Light Green wire) and sensor ground terminal (Dark Blue/Dark Green wire) of wiring harness connector. Turn ignition switch to ON position. Using scan tool, select SENSOR DISPLAY, then EVAPORATOR TEMPERATURE SENSOR. If reading is zero volt, replace evaporator temperature sensor. If reading is not zero volt, go to next step.
- Restore any previously disconnected components and connectors. Using DVOM, backprobe sensor ground circuit between evaporator temperature sensor harness connector and HVAC control module C1 connector terminal No. 2 (Dark Blue/Dark Green wire). See Figure. Turn ignition switch to ON position. If reading is less than .10 volt, go to next step. If reading is .10 volt or more, repair high resistance in sensor ground circuit (Dark Blue/Dark Green wire) as necessary.
- Using DVOM, backprobe evaporator temperature sensor signal circuit between evaporator temperature sensor harness connector and HVAC control module C1 connector terminal No. 15 (Dark Blue/Light Green wire). Turn ignition switch to ON position. If reading is less than .10 volt, replace HVAC control module. If reading is .10 volt or more, repair high resistance in evaporator temperature sensor signal circuit (Dark Blue/Dark Green wire) as necessary.
NOTE:
In step 6), ensure there is good terminal contact between DVOM test lead and wire terminal in harness connector. Ensure DVOM is connected for positive polarity.