Just got back from a good 6 hr roadtrip, and I now have a couple problems with my 99 5.4 with a litle over 170,000 miles.

Number one, my AC. I can only have AC when my controls are on the high level. On the low - mid - high ****. It doesnt matter if it is on AC or Max AC, but it only works when the level is set to high. Very little or no cold air when it is on any of the other levels. My AC is charged. Fuse? Switch? What do you think?

Number 2, knocking noise. This one really pissed me off. The last turn of the day. When I turn right, and only right, there is a knocking/clud like sound comming from the front (drivers side..I think) wheel area. I looked around, and everything seemes to be in order, but I'm not that good at these things. What do you think?

-Alex

 

i dont know about the ac but jack the side of the truck up and see if you can pick the tire strait up and down and move it around it sounds like it may be a hub gone bad i have had that happen a few times

 

Hub or ball joint going bad in the front end. Either way no fun. Sounds like you have a bad control unit for the fan, check fuses and then have the switches checked.

 

Confused, are you talking fan speed or temperature of the incoming air? Blend door if its a temperature thing, and blower resistor if its speed thing.

 

speed of the incoming air. Everything runs great when it is on high, but the other speeds produce little or no air. What is involved in fixing this?

I will jack it up today and see what happenes...thanks

 

Blower resister is no good, it drops the voltage to the fan for slower speeds, high speed is wired direct. The resistor is bolted to the heater/AC plenium chamber somewhere next to the fan motor itself.