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Ask A. Penland Your Own Question
A. Penland
A. Penland, Ford Senior Master Technician, ASE
Category: Ford
Satisfied Customers: 6667
Experience:  ASE Master Certified, ASE Advanced Gasoline Engine Performance
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My ac is not working.i can clear the pcm and it will work

Customer Question

My ac is not working.i can clear the pcm and it will work until I drive the truck I can also remove the ground cable from battery and it will work until I drive or shut truck off and restart has to be electrical but I at a loss 2004 f150 lariat
JA: What kind of computer do you have?
Customer: I pad
JA: Have you installed any updates recently?
Customer: No
JA: Anything else you want the computer expert to know before I connect you?
Customer: No
Submitted: 3 months ago.
Category: Ford
Expert:  A. Penland replied 3 months ago.

Are you getting any trouble codes in the PCM?
You can get them even if the check engine light is not on.

Customer: replied 3 months ago.
No I am not
Customer: replied 3 months ago.
Hello
Expert:  A. Penland replied 3 months ago.

Is your 2004 F150 the Heritage body style or the new body style?

Customer: replied 3 months ago.
Not for 26.00
Expert:  A. Penland replied 3 months ago.

Is your 2004 F150 the Heritage body style or the new body style?

Ford had 2 different F150s in 2004.

Customer: replied 3 months ago.
Lariat same as 2005
Expert:  A. Penland replied 3 months ago.

Ok.

The PCM controls the AC clutch relays which supplies power to the AC compressor clutch. If the PCM sensors an engine concern electrically mike a miss fire or a bad sensor, it will turn the AC compressor off. Then when you disconnect the battery, you are clearing the memory in the PCM and that is why the AC starts to work till you turn the engine off and restart the engine.

See below.

Customer: replied 3 months ago.
I understand that but with no codes I'm not sure where to look truck runs fine no miss just no air
Expert:  A. Penland replied 3 months ago.

Do you have the digital or manual AC controls?

Customer: replied 3 months ago.
Didgital
Customer: replied 3 months ago.
Digital
Expert:  A. Penland replied 3 months ago.

Do you have the ability to check the AC module and the instrument cluster for trouble codes?

Customer: replied 3 months ago.
No
Expert:  A. Penland replied 3 months ago.

You could have another module telling the PCM to turn the AC system off also.

Below are just the trouble codes and symptom chart for the AC system.

Customer: replied 3 months ago.
How many modules are that can tell the pcm this
Expert:  A. Penland replied 3 months ago.

The EATC(AC), instrument cluster, SJB(Dash Fuse Box) and the PCM itself.

Customer: replied 3 months ago.
Has ford had problems with any of theses
Expert:  A. Penland replied 3 months ago.

Not really, to my knowledge.

Below is the pin point test I would follow at my dealership for this problem.