1982 Mercury LN7 Automatic TransFACTORY OEM SERVICE PROCEDURE

Preparation For Testing

  1. Attach Low and High Side gauges to system.
  2. Start engine and warm to operating temperature.
  3. Set system to Cool and blower to High.
  4. Open car doors and hood.
  5. Run at fast idle for 2-3 minutes before check.
Air Conditioning System Performance Check

PERFORM TESTS; SHOULD BE IF:
Temperature Check    Temperature Check is: 
  • Switch to Low Blower.
    
  • Close Doors.
    
  • Check Outlet Air Temperature.
 35-45°F Too warm, check function of control levers, heater water valve, cooling system and gauge readings.
Visual Check    Visual Check Shows: 
  • Compressor
 No excess noise; no leaks Noisy, check belts, oil level, seals, gaskets, bearing, reed valves.
  • Condenser
 Free of obstructions Blocked, clean off debris, Plugged, flush with R-12 or replace.
  • Receiver-Drier
 Dry; warm to touch Frosty, check for restriction or moisture saturation. Replace desiccant.
  • Sight Glass
 Clear or few bubbles Bubbly, foamy or streaky, check reference manual and gauge readings.
  • High Side Lines
 Dry; warm to touch; no leaks Frosty or very hot, check for restriction condenser malfunction or R-12 overcharge.
  • Expansion Valve
 Dry Frosty, check for moisture or restriction. Check sensing bulb.
  • Evaporator
 Dry; cold to touch Freezing or warm, check for expansion valve, thermostatic switch or STV malfunction.
  • STV
 Dry; cool to touch Frosty or warm, check for valve malfunction. Check gauge readings.
  • Low Side Lines
 Dry; cool to touch; no leaks Frosty or warm, check for restriction, low R-12 charge, or valve malfunction.
Gauge Readings    Gauge Readings are: 
  • High Side Gauge
 See Pressure Chart.  Above or below normal, refer to "Air Conditioning Diagnosis " chart.
  • Low Side Gauge
 See Pressure Chart.  Above or below normal, refer to "Air Conditioning Diagnosis " chart.
NOTE: For diagnosis with gauges, refer to chart  on following page.
Fig 1: AMBIENT TEMPERATURE/PRESSURE
G09361628Courtesy of NOT AVAILABLE
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.