1975 Ford ThunderbirdFACTORY OEM SERVICE PROCEDURE

System Functional Test

  1. Measure and record height of rear fender opening. Discharge system completely at compressor bleed valve. Place 400 lb. load in trunk or on tailgate. Again measure and record height of rear fender opening. Start and idle engine. Feel compressor to determine if it is operating; if not, check rubber vacuum line for blockage or improper connections. If compressor is still inoperative, replace it. If unit is operating, let it run for 10-15 minutes until compressor stops.
  2. Measure and record height of rear fender opening. Difference between this measurement and measurement after placing weight on vehicle should be 3/4" minimum. If less than 3/4", accelerate-decelerate engine to determine if measurement changes. Remove load from vehicle. After two minutes, measure and record height of rear fender opening. Difference between this measurement and original measurement must not be greater than 1/4".
Factory Service Tools

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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.

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