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HOMESERVICE MANUALSFORD1987THUNDERBIRD BASE, 3.8 3REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1 (HEATER SYSTEM TROUBLE SHOOTING)HEATER SYSTEM TROUBLE SHOOTING
1987 Ford Thunderbird Base, 3.8 3

Heater System Trouble Shooting

1987 Ford Thunderbird Base, 3.8 3SECTION Heater System Trouble Shooting
WARNING: This page does not describe the selected car, but rather 161 other vehicles, including the 1990 Ford Tempo, 1990 Ford Taurus, 1990 Ford Ranger, 1990 Ford RV Cutaway, and 1990 Ford Probe. However, it is still accessible from the selected car via links, so may be relevant.
CONDITION AND POSSIBLE CAUSE

Symptom Possible Cause
Insufficient, Erratic, or No Heat or Defrost
  • Low radiator coolant.
  • Engine overheating.
  • Loose fan belt.
  • Faulty thermostat.
  • Heater core plugged.
  • Loose or misaligned cables.
  • Vacuum hoses collapsed, kinked or crossed.
  • Air flow control doors sticking or binding.
  • Vacuum motor or hose leaks.
  • Defective or kinked water hoses.
  • Blocked air inlet.
  • Vent open.
Too Much Heat
  • Loose or misadjusted cables.
  • Temperature control door stuck fully open.
  • ATC servo improperly adjusted.
Air Flow Changes Direction When Vehicle is Accelerated
  • Vacuum system leak.Cowl Vent System Leaks Air.
  • Vent door not fully closed.
  • Vent door seal damaged.
Cowl Vent System Leaks Air
  • Vent door not fully closed.
  • Vent door seal damaged.
Blower Does Not Operate Properly
  • Blower motor defective.
  • Blower resistor defective.
  • Blower wire harness defective.
  • Blower switch defective.
  • Selector valve switch defective.
Blower Motor Inoperative
  • Blown fuse.
  • Open circuit.
  • Overheated thermal limiter.
  • Defective blower motor.
  • Defective blower switch.
Air Comes Out Of Defroster Outlet In Any Mode Selector Lever Position
  • Vacuum system leak.
RENDER: 1.0x

NO RELATED

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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.