Air Conditioning (A/C) Condenser Fan System Check 1998
Circuit Description
The A/C condenser fan is controlled by the HTCM. The HTCM sends a speed command to the A/C condenser fan buffer which controls the A/C condenser fan speed by pulse width modulating (% duty cycle) the power to the fan. The A/C condenser fan should operate any time the compressor is running or whenever the coolant temperature exceeds the calibration.
Failure Modes
The A/C condenser fan will not operate if:
| • | The fan motor fails |
| • | The A/C condenser fan buffer fails |
| • | The HTCM fails |
| • | Power or ground is lost to the buffer |
| • | One or more of the wires between the components opens or shorts to ground. |
Failure Action
If the A/C condenser fan fails, charging as well as propulsion may be disabled if the temperature of the PIM, the Drive Motor, the coolant, or the Charge Receptacle goes to high. Also, if the compressor is running, high side pressure will continue to build until the compressor is commanded off either due to excessive current draw or excessive high side pressure. Anytime evidence suggests that the compressor has been disabled due to an inoperative A/C condenser fan, you must evacuate the refrigerant and inspect the orifice tube. Excessive high side pressure can cause the orifice tube to be blown out of it's seat and pushed up the refrigerant lines. Failure to replace the orifice tube will lead to improper A/C and Heat Pump operation.
Related DTC's
| • | HTCM 010 |
| • | HTCM 029 |
| • | HTCM 030 |
| • | HTCM 033 |
| • | HTCM 053 |
Telltale illuminated
None
Other Controller Interfaces
| • | BPCM |
| • | DMCM |
Diagnostic Aids
Check the tightness of the female terminal grip with a spare male terminal.
If the problem is intermittent, wiggle the wire harness while viewing watching the A/C Condenser Cooling Fan and see if the fan cuts out.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the HVAC System Check? | -- | Go to Step 2 | Go to HVAC System Check |
2 |
Is the ambient temperature above the specified valve? | 18°C (64.4°F) | Go to Step 4 | Go to Step 3 |
3 |
Does the A/C condensor cooling fan turn on? | -- | No problem found. Go to HVAC System Check | Go to Step 5 |
4 |
Does the A/C condensor cooling fan turn on? | -- | No problem found. Go to HVAC System Check | Go to Step 5 |
5 | Use a scan tool to display A/C request. Does the scan tool display the specified value? | Yes | Go to Step 10 | Go to Step 6 |
6 |
Is the voltage greater than the specified valve? | 10 V | Go to Step 7 | Go to Step 25 |
7 | Backprobe CKT 203 (LT BLU) wire cavity A at the HVAC - C1 connector with a DMM to ground. Is the voltage greater than the specified valve? | 10 V | Go to Step 9 | Go to Step 8 |
8 | Replace HVAC Mode Select Switch. Is the repair complete? | -- | Go to Step 26 | -- |
9 |
Is the repair complete? | -- | Go to Step 26 | -- |
10 |
Is the voltage greater than the specified value? | 0.3 V | Go to Step 11 | Go to Step 12 |
11 | Check for a poor ground CKT 250 (BLK) wire between A/C condensor cooling fan buffer pin D and ground. Is the repair complete? | -- | Go to Step 26 | -- |
12 | Check for voltage at pin A or the A/C condensor cooling fan buffer. Is the voltage greater than the specified value? | 10 V | Go to Step 14 | Go to Step 13 |
13 | Locate and repair the loss of voltage on CKT 1640 (ORN) wire between the A/C condensor cooling fan buffer and the fuse block. Is the repair complete? | -- | Go to Step 26 | -- |
14 | Check for voltage at pin C of the A/C condensor cooling fan buffer. Is the voltage greater than specified? | 10 V | Go to Step 16 | Go to Step 15 |
15 | Locate and repair the loss of voltage on CKT 5620 (ORN) wire between power distribution and A/C condensor cooling fan buffer. Did you complete the repair? | -- | Go to Step 26 | -- |
16 | Backprobe A/C condensor cooling fan buffer. Is the voltage greater than specified? | 1.0 V | Go to Step 20 | Go to Step 17 |
17 | Backprobe pin C13 of the HTCM. Is the voltage greater than specified? | 1.0 V | Go to Step 18 | Go to Step 19 |
18 | Locate and repair the open in CKT 335 (DK GRN) wire between the HTCM and the A/C condensor cooling fan buffer. Is the repair complete? | -- | Go to Step 26 | -- |
19 |
Is the repair complete? | -- | Go to Step 26 | -- |
20 |
Does either cavity indicate voltage above the specified value? | 10 V | Go to Step 22 | Go to Step 21 |
21 | Replace the A/C condensor cooling fan buffer. Is the repair complete? | -- | Go to Step 26 | -- |
22 | Connect a DMM between both cavities at the A/C condensor cooling fan connector. Is the voltage above the specified value? | 10 V | Go to Step 23 | Go to Step 24 |
23 | Replace the A/C condensor cooling fan. Is the repair complete? | -- | Go to Step 26 | -- |
24 | Replace the A/C condensor cooling fan buffer. Is the repair complete? | -- | Go to Step 26 | -- |
25 | Replace HTCM. Is the repair complete? | -- | Go to Step 26 | -- |
26 |
Is the action complete? | -- | Go to HVAC System Check | -- |
