Your car’s air conditioner is working but it’s just not blowing air as it’s supposed to. Maybe it only works with the fan in the highest setting or maybe it doesn’t work at all? Maybe the air will come out through the defroster vents or the floor vents but not through the dash? OK, no sweat. Here’s what to look for.
So, you can hear the fan coming on and changing speeds but you’re not getting much air through the vents. Check your cabin air filter. Most cars have a filter that cleans the air coming in to the cab of the vehicle and they get VERY dirty because folks forget about them. We have a couple spectacular examples here at the shop, and I saw one once that was so dirty and clogged that the fan sucked it in to the ducting. This is a common and easily fixed problem. Well, as long as you don’t let the filter get sucked in to the fan.
Can you hear the fan come on and does the sound change as you turn the fan switch? If you’re only getting one or two speeds out of your fan there are a couple of things it could be. We get vehicles in from time to time where the fan only works on the highest setting because the blower motor resistor is burned out. The blower resistor is a little device that typically bolts up right to the blower motor and allows the fan to work at different speeds. When it fries the only speed remaining is high. If all you have is high speed, I’d condemn the blower resistor right away if I didn’t know anything else. Also, the fan switch in the control head can fail, but that’s a bit more rare. If you have to fiddle with the fan switch to get it to work then it’s on its’ way out. Stop messing with it and replace it.
How obnoxious is it to have your AC working great but it only blows through the defroster or the floor vents? I mean it’s nice to have cool feet but is that really what you wanted? No it isn’t! Well, down deep inside the dash of your vehicle, way in there where there is a bunch of scary wires and black boxes and a sign reading “Herre Thar Be Dragons” are a couple widgets called mode control motors. Sometimes vacuum operated, sometimes electric, they control doors inside the air handling system that direct the air one way and the other. They’re plastic motors in plastic boxes with plastic gears. They’re made cheap as dirt and fail all the time. Most often, but not always, they’ll give you some warning with a noisy “click, click, click”. Some of these are easy enough to access, some are a real bear. When you start hearing that “click” bring it in and have it fixed.
There are a number of automatic climate control systems that are run by a computer in your car. We’re not going in to them because they’re very complex and require a skilled diagnostician.
Hope this helps some.
From your Local Mechanic, All Tune and Lube Total Car Care Tempe Arizona. Complete Auto Repair and Maintenance.