well just as i get my whipple ready for some dyno tuning my a/c goes out. it has been around 100 degrees all this week and it sucks. took my truck into the dealership to get it serviced. i was thinking it might be low on fluid since i had not used it in almost three months. the service manager comes up to me and says you are ready but not ready. your truck needs a new ecm. the tech comes out and tells me everything in the a/c equipment is working but the computer is not letting the a/c work. then they tell me that the computer is under a 8 year/80k mile warranty. so i am getting a new ecm next week.

 

I don't think the ECM can stop the AC from working.

What is "not working" on it?

 

it is just not blowing cold air. i thought it was strange that it was ecm but they said everything else was okay.

 

If it blowing only hot air, its the blend door or the blend door motor. Very common problems.

Search here for what to do and check.
https://www.f150online.com/forums/hvac-69/

I thought my blend door was bad, but it turned out to be the blend door motor.

PS I would get the truck away from that dealer if they still try to tell you its the ECM.

 

Actually the dealer could be correct. I'm looking at my Ford Service Manual Right now and the PCM gets inputs from the AC Cycling switch, AC Evaporator Temperature Sensor, AC Pressure Sensor, and AC High Pressure Switch. If you'd like more information on what each of these switches and sensors do just let me know and I'll cut and paste from the manaul.
Good Luck

 

it turned out to be the tune. the a/c was turned off in the new tune. thanks for the help guys.