Okay I have been on forums before but am a noob here. I have done some searching on this topic but most threads talk about vacuum control of the heating system. I know that vacuum is used to control vent selection for the heater and know vacuum leaks are a problem.

About 6 months ago I bought a 2003 F350 King Ranch to tow my toy hauler. Very happy so far. The one complaint I have is this...

The design of the heater / AC control module for this year of truck does not have a separate AC switch. There is not a separate button to turn the AC on and off and with a separate switch to choose which vent to blow the air through. For this year, I think 99-04, the vent selector switch must be turned all the way to the left and there are two AC Options... AC and Max AC. For both of these options the AC only blows through the dash vents.

Is there anyway to upgrade the in-dash unit to allow you to turn on and off the AC compressor while independently selecting, floor, foor / vent, floor / defrost, vent / defrost, etc... for the vents that the AC blows through?

I live in CA and it can get HOT... I would really like to blow the AC through the floor vents and / or the floor vents and the dash at the same time to provide more even cooling throughout the truck. Also, blowing through the floor vents would provide better cooling to the back seats.

I really appreciate your input... Otherwise very happy with the truck.

 

You sure that you don't have separate buttons to direct the air flow? My 2006 and 2011 F350s both have buttons to select the air flow to defrost, defrost/floor, dash, dash/floor.

I've had a 1993 F150, 1995 full Bronco, and a 1999 Exp. I can't recall the specific hvac buttons, but I don't recall any issues in directing the air flow, so I'm guessing they had similar buttons.

 

If you want a separate A/C switch, you'd have to install it yourself.

Generally, the A/C compressor operates in all positions except VENT (panel), Heat (floor only) and, of course, OFF.

Therefore, you can use the floor/panel setting or floor/defrost and still have A/C operation.

 

Here is a picture of the dash controls I have. Based on the temperature of the air coming out the vents the AC only works when the selector switch is on AC or MAX AC. There is not a separate button, like in later models (Used to have an 06 F150) where there is a push button for to Toggle AC compressror and a dial to select the vents it blow out of...

 

Your ac should work in the dash/floor setting as well as defrost/floor and defrost.

 

Please forgive me but can you explain how to run the compressor with the air coming through the floor? Here is the instruction from the manual... To me this says that the Ac only works through the vents

 

The 99-07 Super Duty trucks (as well as hundreds of other FoMoCo models) all use the same switch (Motorcraft YH1450) if they have factory manual A/C. My 01 behaves exactly as I described and the 01's owner's manual is unequivocal.

I believe that some intern at Ford screwed up your manual (and others) since the instructions are contradictory (see page 37, middle of page for an example). I think someone cut and pasted text from an EATC-equipped vehicle's manual into yours, replacing the correct information for the manual system. The factory service EVTM is also incorrect, it shows the compressor operating in ALL positions except off. The factory workshop manual agrees with my observations and assessment. Mistakes in manuals definitely happen, I've seen a good number of them.

You might want to pop the hood and watch the compressor clutch hub as the various modes are selected. I did... If yours doesn't behave properly, replace the mode selector switch.

 

Thanks to all for your posts. I will check operation of the AC compressor tonight.... and reply back.