My lincoln mk8 AC started cooling some times and not cooling at other times. The outside temperature is always way off from what it should be when the AC stops cooling. My car has about 60,000 miles on it. I had one before this one and it had a AC problem and they had to take out part of the dash to get into the unit to replace some little part. Is this a problem that is ongoing in the 1998 models?

The ambient outside temperature sensor is normally located in the front grille area (outside the cabin) and is only there to display the outside temperature inside in the display.

What you call the 'Solar Sensor' on the top dashboard fascia is an ambient cabin temperature sensor, which does relay cabin temperatures to the BCM

https://www.ebay.com/itm/153020798034

This contradicts and looks nothing like it

https://shop.advanceautoparts.com/find/2004-jaguar-x-type-cabin-air-temperature-sensor.c36050472

There also a sensor in the rear of the mirror to sense the ambient light and turn the headlights on when it is dark and you are in 'Auto Mode'. That one is nothing to do with the AC. On my car that is on the upper dash.

When the car is in sun, the bodywork is heated by the sun and your AC is struggling, when it is in the shade, it isn't and is cool.

Take it back. There is either a leak from when they replaced the parts, or there is a new issue. A pro grade scan tool computer will diagnose the issue based on data from the ECM and BCM.

..

Take it back to your Audi dealer pronto for a quick and thorough assessment.

Air Temperature Control Blend Door Failure No Heat or no AC (dependes on where door sticks)

In all modern cars there is a tiny DC electric motor driven gear drive that moves a plastic door that blends heated and cooled air from the AC and the heater core, this is called (interestedly enough) the air temperature control blend door actuator. The motor that moves this door fails because the door starts sticking from warping, most common complaint is no heat but it can be no AC as well. To replace these parts (blend door and blend door actuator) you must remove the entire dash from the car. Always have this problem confirmed by a dealer or qualified repair shop as it is a very expensive repair.

Other causes of no heat in the cabin are engine thermostats that are stuck open (engine runs cold) or air bubbles in the cooling system.

Hi. Try to check first your refrigerant. One cause of this problem is refrigerant is running low. Did this happened from the time you turn on the AC? or at first AC is cold then after driving for a certain period of time the AC will get warm?

Blowing hot air when set to A/C is almost always a stuck blend door, dead blend door actuator, or a cracked or disconnected blend door actuator vacuum line. The blend door is inside the a/c ducting under the dash, but the actuator will be accessible outside the ducting.

There is a very good chance the Dual Coolant Control Valve has failed. This is located at the botton right side of the engine fan shroud and has 3 heater hoses connected to it. This valve controls heater or AC temperature inside the car.

The cooling fan is required to operate when the engine temperature rises above the maximum operating temperature threshold.
After the car is started, it will usually take some time for this temperature to be reached.
Ensure fan runs when fan control temperature sensor switch demands.

Sounds like the thermostat is trying to stick,and is causing the engine to over heat,therefore condenser is not cooling the freon down enough to cool.Have the thermostat changed and the cooling system bled out,this is most likely the cause.

assuming fuse and relay are good..no fan should be running when the engine is cool/cold, the only time the fan should be running when it reach over operation temperature which then the fan kick on to bring the temperature back down to it operation temperature. both fan work in sync with one another, addition cooling is needed when the ac is running. when the last time have you replace thermostat and Thermos sensor/switch. I would replace both unit if you have not done so. The thermos/switch will turn the fan on when it reach certain temperature and cut off when it sense the temperature drop in the engine.

hi charles,

i don't think the catalyst has something to do with the ac. you mentioned you are in africa and i am assuming it is positive 50 degrees celcius and not negative 50 degrees celcius as stated in your post. i could see a dash before the number 50.

anyway, there is a pressure switch that would de-activate your compressor once the high pressure reaches an abnormal level. and this level could easily be reached at 50 degrees celcius ambient temperature. so it seems there is nothing you can do about it.

i could suggest that you put an adittional fan if you still don't have, to cool the condenser further.
or just try to cool the condenser, while parked, turn the ac on, and doze the condenser with water and observe if the ac would still cut off. if it does not, then the problem is your ambient temperature.

tnx 4 using fixya,

drcool