A/C tested working but it is not

HENRY CALDWELL

MEMBER
2010 FORD MUSTANG
4.6L
V8
2WD
MANUAL
96,000 MILES

The A/C does not blow cold air. We took it to Firestone and they said it was fine. We mentioned that we thought the A/C control unit connected to the head unit might be the issue. We got home and updated the HU software. Still not working. We plugged back in the old A/C control unit plug and disconnected the digital one. Still not cold air. The A/C turns on and blows. The compressor belt engages and spins the compressor. The A/C seemed to quit after we changed out the battery, but could be coincidence. What worried me was the ac control unit was turning on by itself and even blowing hot air early on. Lit the heater wanted to run. We are taking it back to Firestone as a double check. Is there a was to test the cold air bypassing the AC/heat unit? Like unplug it. Or test the computer? Thanks Henry

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

Hi Henry,

They may have checked the AC system but there are two systems at work here. First is the AC compressor and other components in the AC system. The other is the air distribution system which is the blower motor and air doors.

If they checked the pressures and they are ok then more than likely the issue is the bled door. This is controlled by the HVAC unit so if the door is operational then most likely you are correct that it is the control unit. They can test the door operation by using a scan tool and moving the door. If it is commanded to full cold and it goes there and the AC blows cold then you know the controller is the issue. IF they command it with the scan tool and it doesn't move then the actuator is most likely the issue.

Let me know what they find and I will be happy to let you know if it sounds feasible or not. Thanks

https://www.2carpros.com/articles/replace-blend-door-motor