1998 F-150 4x4 AC always on?

The compressor on my '02 F350 runs in most settings, regardless of the temp setting.. Lazy engineering if you ask me.

I doubt SERIOUSLY that there is a problem. Most auto manufacturers lately have set the compressor to run on most settings. Why? To remove humidity from the cabin. It makes sense that if you need to defog the interior of your windshield, that you have excess humidity. Most of the time, the compressor is off on the vent setting and the floor only setting. Any blend between floor and defrost will get the compressor. I can see the logic of keeping the compressor on when in the floor setting though. Usually floor is used for heat in the winter, one of the hardest times of the year to keep moisture from collecting inside the car (because of snow tracked inside)

CJB

The ac in my 99 ranger runs regardless of temp setting in all positions except 'floor' or 'panel'. Anything else and ford claims its dehumidifying.

It is just lazy.

This would be FAQ, if we had one. It's been asked 100 times. It's made that way, and that's about all you have to say.

Well if that's how its made I'm not impressed. What I am going to do is install a switch and turn it off when I want it off and see if my gas mileage improves.

Thanks to everyone that replied.

That would be exactly how it is supposed to work. The reason is humidity reduction to help prevent window fogging and help keep the cab dried out for those of us who are in and out in the rain or snow. Below about 40 deg ambient temp, the compressor is not used anyway. It is good for the compressor to operate some to keep the oil circulating inside the system. Lastly, you will not save much on gas on these nice days by driving with the windows open instead of the a/c. I have kept detailed mileage logs for years. All of the Fords I have had - at least on the highway - have gotten better fuel mileage with the a/c running instead of the windows open. Modern compressor just do not require the fuel the old compressors did.

BTW, on some vehicles, disconnecting the compressor electrically will set a fault code in the ECM. The ECM uses this bit of info to control idle speed. It also cuts out the compressor at near full throttle to prevent overspeed damage to the compressor and allow full engine power to the wheels.

Good luck Lugnut

I believe you can control that by turning your temperature control setting down just a bit. We own Fords exclusively, and in both my '99 F350 and my wifes '03 SportTrack and '04 Explorer, there is a mark on the temp faceplate where the compressor goes off.

Maybe not on yours, but maybe that'll help.

Spdloader

And.....you will defeat the functionality of the system. It doesn't matter if you are heating or cooling. The output is a blend of both the heating system and the cooling system. The only thing the temperature control does, is control the register that determines how much hot air is mixed with the cold.

I decided to just leave the AC system alone and not install a switch.

Thanks to everyone for all the great input.

Most japanese vehicles seem to have a button to turn the compressor on and off. I guess the american manufacturers don't trust us to use this properly. What a total waste of fuel! I like being able to run hot air on my windsheild without the compressor running.

You are proof that they are correct.

What a total waste of fuel! I like being able to run hot air

Defrost or demist is the one time when it makes sense to have the compressor running because it dehimidifies the air. Do you have any idea what happens when you blow warm moist air against cold glass?

Hmm, lets see, the moisture will condense and thus killing my visibility. I actually have never had this happen. If it does, I just push the button.

what bugs me about it, is the settings make no sense. Dehumidify the windscreen and the floor, I can understand that. But the ranger dosnt run the dehumidifyer on the floor. Not unless you switch to floor/panel combined. And why then?!

You get what you pay for.

Because the evidence of excessive humidity is the fogging of the window. If you don't have excessive humidity, then you don't need to dehumidify. Seems pretty simple to me.

CJB