Intermittent A/C light issue

WHODEY00

MEMBER
2005 MAZDA 3
2.3L
4 CYL
2WD
AUTOMATIC
150,000 MILES

The A/C green light only seems to want to work when the temperature is colder outside. For example, right now it’s 63 outside and it works fine. Another weird thing is that in the summer I found to get the A/C to blow cold air sometimes if you move the air control knob between 3 and 4 sometimes the air blows cold air but usually then the green A/C light flickers and stops working.

1 Reply

STEVE W.

MECHANIC
13,002 POSTS

Is it just the indicator or does the A/C also not work? If it's only the indicator but the A/C still works fine, it likely is a failing LED in the control head. If, however, the A/C also doesn't work unless it's colder out it could be a couple items. One being that the switch for the A/C has a bad solder connection on the board and it only works until the warmer temperatures cause the board to shift and the connection fails. Repair for that would be to remove the HVAC control and reflow the solder. The other could be a bad wiring connector that is acting in a similar fashion. As you have an issue with the control knob as well, I would lean more toward the bad solder joint.
A low refrigerant charge would work the opposite with the higher temperature letting the system to operate as the pressures would be higher in the warmer weather.
There are places that repair the control hears that have an online presence.
This is a decent video on its removal as it is not really that easy to explain. Watch the plastic trim, 15-year-old plastic can be very brittle.
https://www.youtube.com/watch?v=kdcZ1hy1m1c