Heating & Air Conditioning - Non-Dtc Diagnostics: Diagnosis RAM Pickup 2500

HVAC SYSTEM TEST

For a complete wiring diagram, refer to appropriate SYSTEM WIRING DIAGRAMS article .

Diagnostic Test

1. HVAC SYSTEM TEST NOTE: Diagnose and repair all active DTCs before diagnosing and repairing stored DTCs. If active DTCs are present and perform the appropriate diagnostic procedure. Refer to appropriate HVAC Electrical Diagnostics Information . Make a selection based on the symptom, condition, or DTC that you want to diagnose. Scan Tool Indicates HVAC Not Active On Bus and perform the No Response from HVAC diagnostic procedure. Refer to appropriate Diagnostics / Communication - Diagnosis and Testing Information . Blower Motor Inoperative for Blower Motor diagnostic procedures. Refer to «Diagnosis and Testing»(ref-457873-S33196097792012030200000) . Actuator Calibration Test Go To 4 . A/C System Performance Test Go To 2 .
2. A/C COOLDOWN TEST The following are prerequisites of the A/C Cooldown Test. Verify that the: Refrigerant system has an adequate charge. Check and repair as necessary before proceeding in accordance with the Service Information. Refer to «Diagnosis and Testing»(ref-457787-S09173920312012030200000) . Blower motor operates correctly in all speeds. Diagnose and repair all blower related faults before proceeding. Work area ambient temperature is above 16° C (60° F) before proceeding. Move the vehicle to a warmer work area if necessary. Evaporator temperature is above 13° C (55° F) before proceeding. A/C compressor is not running. If the compressor is running, turn the A/C off and allow the evaporator to warm up before proceeding. NOTE: Running the AC Cooldown test will cause the A/C status indicator to flash. One or more status messages will display on the scan tool after running the Cooldown Test. These messages will clear after paging back out of this test function. Therefore, it is important to note all messages before doing so. Start the engine. Turn the Blower control to the high speed position. With the scan tool in HVAC, select System Tests and then select Cooldown test. Allow the test to run to completion. Does the scan tool display a status message that indicates a fault has occurred? Yes and perform the appropriate diagnostic procedure. Refer to appropriate HVAC Electrical Diagnostics Information . No Go To 3 .
3. MODE SWITCH AND DOOR ACTUATOR CIRCUIT TEST NOTE: If at anytime a DTC becomes active during this test, proceed to the conclusion question. If multiple DTCs are active, diagnose those that relate to a short circuit first. Start the engine and turn the Blower control to the low speed position. Set the Blend control (single-zone) or Driver and Passenger Blend control (dual-zone) to the full cold position. Monitor the scan tool for active HVAC DTCs while performing the following test steps. If equipped, press the A/C mode switch on, wait 30 seconds, and then press it off. On Dual-Zone systems, press the Recirculation mode switch on, wait 30 seconds, and then press it off. If equipped, press the EBL mode switch on, wait 30 seconds, and then press it off. Move the Blend control (single-zone) or Driver Blend control (dual-zone) from full cold to full hot, wait 30 seconds, and then move it back to full cold. If equipped, move the Passenger Blend control from full cold to full hot, wait 30 seconds, and then moved it back to full cold. Turn the Mode select control to the defrost position, wait 30 seconds, and then turn it to the panel position (dual-zone) or panel / recirculation position (single-zone). Wait 30 seconds before proceeding. Does the scan tool display any active DTCs? Yes and perform the appropriate diagnostic procedure. Refer to appropriate HVAC Electrical Diagnostics Information . No Go To 4 .
4. ACTUATOR CALIBRATION TEST Ignition on, engine not running. With the scan tool, select Actuator Calibration Test. When the test is complete, read HVAC DTCs. Does the scan tool display any DTCs? Yes and perform the appropriate diagnostic procedure. Refer to appropriate HVAC Electrical Diagnostics Information . No Test Complete.

Scheme 1

For a complete wiring diagram, refer to appropriate SYSTEM WIRING DIAGRAMS article .

Scheme 2

Scheme 3

Scheme 4

Scheme 5

Scheme 6

1. CHECK FOR DTCs IN THE TIPM Turn the ignition on. Using the scan tool, read TIPM DTCs. Does the scan tool display any DTCs? Yes Diagnose and repair the DTCs. Refer to appropriate Diagnostic and Testing Information No Go To 2 .
2. CHECK OUTPUT FROM THE TIPM ON THE (F942) FUSED IGNITION SWITCH OUTPUT (RUN-START) CIRCUIT Turn the ignition off. Disconnect the Blower Motor harness connector. Turn the ignition on. With a scan tool in TIPM, select Actuators, and actuate the Blower Motor. Using the 12-volt test light connected to ground, probe the (F942) Fused Ignition Switch Output (Run-Start) circuit in the Blower Motor harness connector. Does the test light illuminate brightly? Yes Go To 3 . No Go To 4 .
3. CHECK (C70) BLOWER MOTOR HIGH DRIVER CIRCUIT AND (Z134) GROUND CIRCUIT FUNCTION Turn the ignition off. Turn the blower control on. NOTE: The test light should be illuminated and bright. Compared the brightness to that of a direct connection to the battery. Using a 12-volt test light connected to 12 Volts, probe the (C70) Blower Motor High Driver circuit in the Blower Motor harness connector. Does the test light illuminate brightly? Yes Replace the Blower Motor in accordance with the Service Information. Perform the BODY VERIFICATION TEST. Refer to «BODY VERIFICATION TEST»(ref-457926-S40044966262012030200000) for 1500, 2500 & 3500, or «BODY VERIFICATION TEST»(ref-457927-S20352278932012030200000) for 3500 CAB & CHASSIS, 4500 & 5500 . No Go To 5 .
4. CHECK THE (F942) FUSED IGNITION SWITCH OUTPUT (RUN-START) CIRCUIT FOR AN OPEN Turn the ignition off. Disconnect the TIPM C3 harness connector. Measure the resistance of the (F942) Fused Ignition Switch Output (Run-Start) circuit between the TIPM C3 harness connector and the Blower Motor harness connector. Is the resistance below 5.0 Ohms? Yes Replace the TIPM in accordance with the Service Information. Perform the BODY VERIFICATION TEST. Refer to «BODY VERIFICATION TEST»(ref-457926-S40044966262012030200000) for 1500, 2500 & 3500, or «BODY VERIFICATION TEST»(ref-457927-S20352278932012030200000) for 3500 CAB & CHASSIS, 4500 & 5500 . No Repair the (F942) Fused Ignition Switch Output (Run-Start) circuit for an open. Perform the BODY VERIFICATION TEST. Refer to «BODY VERIFICATION TEST»(ref-457926-S40044966262012030200000) for 1500, 2500 & 3500, or «BODY VERIFICATION TEST»(ref-457927-S20352278932012030200000) for 3500 CAB & CHASSIS, 4500 & 5500 .
5. CHECK THE (C70) BLOWER MOTOR HIGH DRIVER CIRCUIT FOR AN OPEN Disconnect the A/C Heater Control C2 harness connector. Measure the resistance of the (C70) Blower Motor High Driver circuit between the A/C Heater Control C2 harness connector and the Blower Motor harness connector. Is the resistance below 5.0 Ohms? Yes Go To 6 . No Repair the (C70) Blower Motor High Driver circuit for an open. Perform the BODY VERIFICATION TEST. Refer to «BODY VERIFICATION TEST»(ref-457926-S40044966262012030200000) for 1500, 2500 & 3500, or «BODY VERIFICATION TEST»(ref-457927-S20352278932012030200000) for 3500 CAB & CHASSIS, 4500 & 5500 .
6. CHECK THE (Z134) GROUND CIRCUIT FOR AN OPEN Measure the resistance of the (Z134) Ground circuit between ground and the A/C Heater Control C2 harness connector. Is the resistance below 5.0 Ohms? Yes Replace the A/C Heater Control in accordance with the Service Information. No Repair the (Z134) Ground circuit for an open. Perform the BODY VERIFICATION TEST. Refer to «BODY VERIFICATION TEST»(ref-457926-S40044966262012030200000) for 1500, 2500 & 3500, or «BODY VERIFICATION TEST»(ref-457927-S20352278932012030200000) for 3500 CAB & CHASSIS, 4500 & 5500 .