A/C - Climate Control Operation Information
87 09 08Oct. 15, 2009
2018511 Supersedes T.B. Group 87 number 08-05 dated Aug. 11, 2008 to update warranty detail.
Vehicle Information
Condition
Climatic Controls Operation
Customer perceives selected temperature is not blowing the same temperature as selected.
Technical Background
Climatic controls the air temperature so that selected temperatures are reached as soon as possible, and then remain constant.
Temperature requests are relayed to the control module by a potentiometer in the rotary switch.
The information in this Technical Bulletin is to verify the controls are operating to specifications.
Production Solution
Not applicable.
Service
^ Connect VAS 5051B, 5052/A.
Tip:
Engine must be running with minimum coolant operating temperature of 87� Celsius (190° F). (see measuring value block 4/4).
^ Open all doors and windows to equalize cabin temperature and ambient air temperature.
Tip:
Do not use instrument cluster display to verify ambient or coolant temperature. (use measuring value blocks 4 group 4, and confirm ambient temperature with an external source i.e. thermometer, thermocouple).
^ Select air distribution selection to center vents.
^ Close all side vents but keep center vents open.
^ Turn blower speed to 1 and press A/C button to turn system ON.
^ Turn off the air recirculation.
^ Insert a thermometer or thermocouple into center vent to obtain measurements.
Tip:
Allow approximately 2 minutes for temperature to reach and maintain the stated temperature as shown on table.
Temperature measurements on the table below are for reference only, Actual values may vary.
1. Validate the temperature at the minimum temperature (position 1).
2. Validate the temperature at the mid temperature (position 5).
3. Validate the temperature at the maximum temperature (position 9).
4. Validate the temperature variation at a position between (position 1) and (position 5)
5. Validate the temperature variation at a position between (position 5) and (position 9).
If temperature measurements are within a negligible range of table readings, system is operating to specifications and no further diagnosis is necessary.
Advise customer the system is operating as designed, and refer customer to owner's manual for description of system operation.
If the temperature did not adjust within minimum and maximum positions:
^ Replace Heating and A/C control, see Repair Manual Group 87, Air Conditioning, in ElsaWeb.
Warranty
Required Parts and Tools
No Special Parts Required.
Additional Information
All part and service references provided in this Technical Bulletin are subject to change and/or removal.
Always check with your Parts Dept. and Repair Manuals for the latest information.