Anyone out there experience an Air Conditioner that continues to blow cold air even when a mode other than A/C or Max A/C is selected? I've tried multiple combinations of selections and unless the heat dial is turned to red, its blowing COLD air. Fan, and everything else works fine.
Suggestions appreciated! :-) If the compressor is running all the time, its going to make my already poor mileage even worse.

1999 F250 SD 7.3litre

 

This comes from my experience with my 2000 SD, and I asked my dealer the same thing when it was new.

The air conditioning will be on in every position selected except, Floor and Vent (first click left from off), other than that it's on.

Also, the compressor will occasionally engage at various times during normal operation, even without any air conditioning on. I was told that this is part of the 7.3 intercooler operation. Made sense to me.

 

Slight correction, it will run in all positions except vent and floor. It runs it in defrost to dehumidify the air and defog the windows.

However, if you are having trouble with selecting warmer air, you could have a problem with the blend door motor. It's a common failure point of the hvac system.

 

Thanks Chris...

 

Yep. Blend door actuator. It's a common enough problem on Fords in general, not just the SDs, it seems.

 

Thanks for the responses. I'm not sure i understand tho. Are you saying that there is no way to turn on the fan and just blow outside air in the 'mix' mode (vent and floor) without it being cooled? What if it's February outside, and both my toes and my nose is cold? Even if thats the case, it's blowing cold air in the Floor and Vent mode too.
So if the problem is the Blend Door actuator, can you suggest how I might check/replace it? How deep is it burried??
Thanks again.

 

The blend door actuator blends the air temp - hot & cold. Other actuators control where the air goes, and are independant of the blend door. The blend door actuator is on the heater core/evaporator housing box under the dash. I haven't looked for it in this truck yet (no need) but it will probably be tough to get at. Look up the shpp manuals in the tech folder at the top of this forum and you should be able to find diagrams.

If you don't fix it, you will be blowing full cold in Feb, from the looks of it. Now if you put the control on FLOOR or VENT, then the AC will not turn on, you will just blow fresh air.

-Dave

 

Thanks Dave. I'm searching the top of this page and can't find a Tech Folder or Shop Manuals anywhere. I'd love to see a diagram of whats happening in the bowels of these ducts.
To clarify ... no matter what mode i select, unit blows COLD air conditioned air. Only way to not have icy air blowing at my head or feet or both or even defrost is to crank up the heat dial, which i suspect is just adding hot air to cold conditioned air.

 

True... unless in vent or floor only mode.

 

Weird thing happened to me a few years back - blend door stuck and wouldn't move. While everything was on and running, I unplugged the connector to the blend door servo and plugged it back in. It's worked every since.

 

well, if you are getting cold air and have confirmed the a/c unit is running in vent and floor mode something is wrong, however, I doubt that is the case. There really isn't a way for that to happen. I have to set my truck on midway or better, even in vent mode. The a/c won't run below a certain temperature, just by the nature of a refrigeration system.

On a 7.3L you won't see a difference in mileage with a/c on or off. It's just too big to make a difference.

 

Thank you guys.
Consensus seems to be that I've lost my mind and it is not physically possible to blow conditioned air while in FLOOR or VENT. I'm having trouble believing this. Temperature sensors in my hands have worked reliably for many years.
So my questions remain tho... where is this Blend Door (and servo) located, so I can give it a little smack. Is it accessable in less than a month of truck dash disassembly?Also, I still can't find this Tech Folder or Shop Manual that you refer to Dave.
Dan

 

That was never clarified, and no one said it wasn't possible. But some, (including me) thought initially that the SD A/C should only come on in A/C mode. We were just telling you that isn't the case. Good Luck!

 

I'm not Dave but I'll butt in and answer it for ya. Go to the "Super Duty and Heavy Duty" forum's page and the Tech folder thread will be the first one in the line up.

Good luck!

 

Here's the link. See post 39, and pick your year:
https://www.ford-trucks.com/forums/7...manuals-3.html