I’ve recently encountered an odd AC issue with my 2007 Mazda3 that I cannot find any other message boards addressing. For a variety of reasons, I had occasion to drive 17 hours straight from the SF Bay Area to Albuquerque NM on one day and then 10 hours to Oklahoma the next day at the end of July. The first 6-7 hours were fine with the AC blowing as normal, on a 100+ degree day. The problems began to occur deep into the drive where the speed of the blower decreased substantially, regardless of the speed setting. The air coming out was cold, but at very low volume.
I suffered through the next 6 hours or so until about 7pm, when I pulled in for another tank of gas and bite to eat. Starting up the car the fan starting blowing normally , temp was still around 100+, and ran fine through the evening until I hit Albuquerque 7 or 8 hours late. Thinking I made it through the blast oven, I started the next day in fine shape with the AC working normally, until another 6 hours into the drive to Oklahoma, the fan again slowed dramatically. No improvement on the fan speed until later that after arriving in OK and checking into the hotel I went back to the car to get a bite to eat and the AC fan was working normally again. Might I add, no problems have resurfaced in the ensuing months, although I also haven’t had to drive it more than 1-2 hours at a time in the last 3 months.
Anyone have any ideas? Could lines freeze up after hours of usage and block the airflow? I have no idea.