Questions and Answers

Ford Taurus A/C Works For A While Q. Thanks for taking my question. I have a 1996 Ford Taurus SHO with approximately 126,000 miles. I have replaced the transmission to the tune of $2,799.00 two years ago. Car has been running fine until now. The A/C will work fine in 80° or cooler outside. When it gets above 80°, the A/C will blow super cold air for about 20 to 25 minutes, then go hot.

If I am in stop and go driving, it will start blowing hot air sooner. The "weird" thing about this, is when the A/C is running nice and cool, my RPM's will bounce all around, when the A/C starts going hot, the RPM's are smooth as can be with no jumping around at all.

A friend of mine put his gauges on the unit and boosted it with some freon but that did nothing. He said a bunch of things I totally didn't understand about the high side and low side and how he didn't think it was the compressor.

I really don't want to spend a lot more money on this car and am hoping and praying it'll be something I can afford. Furthermore, my windshield wipers seem to have a mind of their own, when I have them on they will hesitate and go fast, then real slow, then normal. Besides trading in the car, is there any hope for my SHO???

Thanks for your help!

A. The first thing I would check is that the system has the proper amount of refrigerant in it. Too much or too little can cause this problem to occur. Also check the system pressures. That will tell you if there is a blockage in the system.

If you leave the system in RECIRC, the evaporator core could be freezing up, especially on humid days. Putting the system in FRESH air mode will help keep the evaporator fore from freezing.

Next thing to check is proper cooling fan(s) operation. Proper operation is:

1. Cooling fan motors will run at low speed if:
   1. The engine temperature is higher than normal. Cooling fan motors start running at 216°F and stops running at 212°F.
   2. The A/C is on and the vehicle speed does not provide enough natural airflow. The cooling fan motors will stop running at speeds over 38 mph if coolant temperature is below 212°F and A/C head pressure is below 250 psi. NOTE: The cooling fan motors will not cycle with the A/C clutch. The cooling fan motors will come on when the A/C switch is turned ON.

2. The cooling fan motors will run at high speed if:
   1. The engine temperature is higher than desirable and cooling fan motors have been operating at low speed. The cooling fan motors start running at high speed when the coolant temperature exceeds 228°F and return to low speed when coolant temperature drops to 222°F.
   2. A Wide-Open Throttle (WOT) A/C cutout is used during hard acceleration. A signal is sent to the powertrain control module which then signals the CCRM to cut off power to the A/C clutch field coil. This keeps the engine from being overloaded.

The Powertrain Control Module (PCM) controls cooling fan operation so a bad PCM, while not likely, is a possibility. A bad coolant Temperature sensor can also cause the fans not to come on.