Originally Posted by justinp95
Is there a write up around here for it? I dont see how a hole in a vacuum line can make chatter/Chopping sound and not a whistle?
2005/06 A/C or Ventilation Control Problems:
Trucks built between 9-15-04 to 6-8-05 may blow air out of the defrost vents with the mode selector in other positions. The vacuum pump may also run excessivly. Lower the glove box and inspect the vacuum lines to see if they are wraped around the panel/floor door actuator rod. If the hoses are wraped around the rod, inspect for damage to the hoses. If the hoses cannot be repaired, replace them with part number 5C3Z-19D699-AA for automatic temp control or 5C3Z-19D699-BA for manual climate control.
Vacuum Pump Inop or Ventilation System Deverts to, or Only Blows Through, Defrost Vents:
If the vents devert to the defrost mode, this is usually due to a leak in the vacuum system. Typically if the problem is in the automatic hub system, this will only occur when 4X4 is selected. If it occurs on in a specifc ventilation mode, the vacuum servos associated with that selection would be suspect. If the ventilation system stays on defrost at all times, a leak in the system at the vacuum pump, or the vacuum pump itself may be at fault. For vacuum pumps that are inoperative or continuously running, replace with P/N 4C3Z-2A451-AB. Broadcast Message 1244, 1575, 3278; TSB #04-16-08