A/C blows warm when idling

Tiny
RIDEORDIE0719
  • MEMBER
  • 1992 LINCOLN TOWN CAR
  • 0.5L
  • V8
  • 2WD
  • AUTOMATIC
  • 96,000 MILES
A/C blows cold while vehicle is in motion. If I come to a stop at a traffic light or while sitting in a drive-thru, A/C blows warm. Basically whenever the vehicle is stopped, the A/C blows warm air only. Happens seconds after coming to a stop. What I’ve tried with no improvement: Adding Freon.
Wednesday, July 8th, 2020 AT 7:09 AM

1 Reply

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning,

This happens from the lack of airflow through the radiator or the cooling fan not working on high speed.

When it is at idle, does the cooling fan work at high speed?

I would clean the fins of the radiator and condenser as the lack of airflow will cause the A/C to be warm at idle.

Roy

To prevent silicone fluid from draining into fan drive bearing, do not store or place drive unit on bench with rear of shaft pointing downward. The removal procedure for either type of fan clutch assembly is generally the same for all cars. Merely unfasten the unit from the water pump and remove the assembly from the car.
The variable speed fan with flat bi-metal thermostatic spring may be partially disassembled for inspection and cleaning. Remove screws holding the assembly together and separate the fan from the drive clutch. Next remove the metal strip on the front by pushing one end of it toward the fan clutch body so it clears the retaining bracket. Then push the strip to the side so that its opposite end will spring out of place. Now remove the small control piston underneath it.
Check the piston for free movement of the coupling device. If the piston sticks, clean it with emery cloth. If the bi-metal strip is damaged, replace the entire unit. These strips are not interchangeable.
When reassembling, install the control piston so that the projection on the end of it will contact the metal strip. Then install the metal strip. After reassembly, clean the clutch drive with a cloth soaked in solvent. Avoid dipping the clutch assembly in any type of liquid. Install the assembly in the reverse order of removal.
The coil spring type of fan clutch cannot be disassembled, serviced or repaired. If it does not function properly it must be replaced with a new unit.

Testing

Do not operate the engine until the fan has been first checked for possible cracks and separations.
Run engine at a fast idle speed (1000 RPM) until normal operating temperature is reached. This process can be done more quickly by blocking off the front of the radiator with cardboard. Regardless of temperatures, unit must be operated for at least five minutes immediately before being tested.
Stop engine and using a glove or a cloth to protect the hand, immediately check the effort required to turn the fan. If considerable effort is required, it can be assumed that coupling is operating satisfactorily. If very little effort is required to turn the fan, it is an indication that the coupling is not operating properly and should be replaced.

Bi-Metallic Coiled Spring Removal
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The clutch fan may be tested while vehicle is being driven. To check, disconnect the bimetal spring, Fig. 2, and rotate 90° counterclockwise. This disables the temperature-controlled, free-wheeling feature and the clutch performs like a conventional fan. If this cures the overheating condition, replace the clutch fan.
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Saturday, July 11th, 2020 AT 4:25 AM

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