Hey Guys, this one has me 100% stumped! On my 2004 Lariat Screw my ac just stopped 2 days ago. The screen (I have the numbers on my center console) keeps changing back to 75 every time I get out of my vehicle, almost as if the ac controls don’t remember where they were set.

Now, I have NOTHING! No heat, no ac, zip! I have checked every fuse, relay and ground. Everything is fine. The oddest thing is that there is NO power at the blower motor relay, at the blower motor, at the blower motor resistor.

That lead me to believe the actual ac/heat head unit is bad and isn’t sending the signal to the relay to turn the fan on. Problem is, Ford and everyone else tells me that this part is discontinued!

I have NO idea what to try next. All fuses good, all relays good, No power to the blower motor relay, blower motor resistor, or obviously the blower motor.

Please help!! Oh, ya the AC is cycling...I can feel very cold air coming through the vents but the fan motor isn’t being told to turn on!

The other thing that must be connected somehow is how the lights in my AC controls are acting up. They will turn on with my headlight switch but as soon as my fog lights turn on the lights go out! It makes no sense, and leads me to believe this is a ground issue but my truck has zero rust(Florida truck) and hasn’t been modified in any way.

Im told the Ford part number for the AC control panel is 4L3Z1998OBD but that it’s no longer made. I have NO clue what to try next! Thank you.

Well this is BAD news! I took my truck to the dealer since I wasn’t getting power past the relay in the fuse box. I just received a call telling me that one of the ”mini computers” on the back of the fuse box is bad. The entire fuse box needs to be replaced, keys reprogrammed, etc. This truck has given me 15 years of relatively trouble free use but now it’s going to cost at least $900 to fix it. I feel helpless. Having a brother that works for Ford in Dearborn I have always had the knowledge I needed to fix anything. Not this time.