Lincoln Aviator, Ford Explorer, Exp Sport, Exp Sport-Trac, Mercury Mountaineer 2000-2005

Air Conditioning System Diagnosis


Inspection & Verification

  1. Verify the customer concern by operating the climate control system to duplicate the condition.
  3. Visually inspect for obvious signs of mechanical or electrical damage, including the following:


Loose, missing or damaged A/C compressor drive belt
A/C compressor inoperative
Loose, misrouted or damaged vacuum lines
Broken or leaking vacuum control motor
Discharged A/C system
Broken or leaking refrigerant lines


Smart junction box (SJB) fuses
Battery junction box (BJB) fuses
Blower motor
Loose or disconnected A/C clutch connector
Circuitry open/shorted
Disconnected, loose fitting or incorrectly installed electrical connectors and pins

A leak in the vacuum control circuit may occur during acceleration (slow leak), may exist at all times (large leak), and may exist only when specific functions are selected (indicating a leak in that portion of the circuit). The vacuum hoses used in the passenger compartment control circuit are constructed from PVC plastic material. The vacuum hoses used in the engine compartment are constructed of Hytrel®. Because of the materials used, never pinch the vacuum hoses off during diagnosis to locate a leak. A golf tee can be used as a plug when it is necessary to plug one end of the vacuum hose for leak test purposes.

  1. As tests and measurements are being carried out, be sure to inspect for any disconnected, loose-fitting or incorrectly installed component, module and in-line electrical connectors and pins.
  3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding with any further tests or repairs.