Guys,

I need some help. I have a 2003 ford excurison with a 7.3. when I have my vent on and temp set low but no AC on the vents are blowing hot air when the air temp outside is not hot 60-70. I was thinking I had a bad air blend actuator or broken blend door. I put the truck in the ford dealership to get the fuel filter changed and asked if they could diagnose the problem. The AC seemed to be working fine when it was set to AC and blowing cold but as soon as the truck was heated up and AC turned off the vents blow hot air. The dealer diagnosed it and said the freon was low and said the compressor kicks in regardless of whether the AC or defrost is on and said that was the problem. They didn't have time to further diagnose the system due to it being Saturday. He said the mechanic didn't have time to check the air blend actuator or door but feels confident if the freon is charged it will fix the problem. The question I have is the AC compressor supposed to come on when you don't have the AC or defroster turned on? I was never aware of this and left feeling like I was given bad information but then again I am not a mechanic so was hoping one of you guys that may no could let me know.

 

Compressor should only be on when in A/C or defrost. If the outside temps are in the 60's and you're moving the vent air should be cool, I could understand it warming up if you were sitting/stopped with the engine running.

Sounds like a blend door to me.

 

My recollection is that the air conditioner runs in all switch positions other than floor, vent, or off. The vented air will pick up some of the engine heat because the engine circulates hot water to the heat exchanger (radiator) of the cooling/heating system. You could put a valve in the line going to the heat exchanger and you would have air at ambient temperature and your air conditioner will be colder. Many of us have put a valve in the line.

 

Deleted, nevermind.

 

Neal said it right. Look up air conditioning mods and Robin years back along with others posted go mods for this fix. Its common in are trucks.

 

I haven't pulled the HVAC box apart myself, but rumor has it there's a foam seal on the blend door that gets eroded and leaks between the hot and cold sides over time. Maybe someone who has opened one up will see this and confirm or deny it. I put a 1/4 turn ball valve in the line to my heater core years ago, and it immediately lowered the temps at the dash by a good amount.

Of course yesterday I turned the air on for the first time this year, and the compressor didn't run, so now I have to diagnose that. If it ain't one thing, it's another, I tells ya

 

Here you go...

 

Guys,

I have bought two replacement dorman blend door actuators. Both of them had the arm about 90 degrees set different than the stock one I pulled out. I had heard that it is not good to power them up without installing them in the blend door hole as they could spin past a normal positioning point and then not work. Needless to say, the second I connected power to them they moved about 90 degress in the exact positon of the one that stopped moving to begin with. I have been doing a lot of reading about what the possible causes of the blend door actuator not working and wondered if I have a bad inside air temperature sensor. I know where the exterior temperature sensor is in front of the grill on the drivers side but for the life of me I can't find any reference to the inside air temperature sensor in my haynes manual or anywhere on the internet. Does anyone know if a 2003 ford excursion 7.3 has an inside air temperature sensor and if so where it may be located or any picture of one? I would greatly appreciate it.

 

Can you see those four small horizontal slots cut into the lower dashboard just to the right of the steering wheel, directly above the driver's right knee?

Behind those four little slots lies an inside climate control sensor on 2002 and up Excursions and Super Duties.