I have an 03 SCrew Lariat, 2WD with 140k miles. Over the summer the AC started working intermittently. It would always blow cold but very faintly, when the engine was under a load. What it wasn't then the AC would kick on normal power. I just lived with it because I don't drive much and it was still ok for me.

Now that the weather is colder I started using the heat a few times. The heat blows very lightly all the time and never kicks on full power. Seems like it might be related to the fans?? I put a new fan clutch on a couple months ago so that should be good.

Any ideas?

 

Do you have automatic climate control or manual? If manual are you saying the fan only blows one or two speeds? If so it could be the blower motor resistor.

 

It's automatic climate control. I never really understood what that means. I use the automatic button when using the AC but for heat I use the vent button. Maybe I'm doing that wrong?

When I increase the fan speed it sounds like the air is coming out of the front defroster vent for both AC and heat. With the AC, when it kicks on normally, that sound and feel shifts to the vents like normal.

 

Automatic will automatically adjust temp, fan speed, and where the air is directed based on a few different things. If you take it out of automatic mode then it should do as you tell it with the buttons. If you put it on the dash vents and it sounds (feels?) like its coming out of the defroster you may have a selector motor problem. Like I said I never had to work on my HVAC in my 02 so I can't be much help. Just trying to point you in some possible directions.

 

Maybe im doing it wrong - i have the automatic climate control on my 03 s-crew- i set the direction (colder weather: defrost/floor) then set the temp. and fan speed- when cabin temp. is met, the fan slows and you can hear the damper move. If i change the temp. the fan speeds up and the damper moves again. Then if i turn the temp below the outside temp it slows almost to nothing and the damper closes.(all this and the direction never changes it stays where i set it)

 

Try taking it off of automatic. When it first starts cold it will do specific things until it warms up then when it reaches the set temp it will do something else. I can't tell you what specifically but it makes changes based on at least those criteria. When in automatic.