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My 2002 Ford Explorer developed a weak defrost late in the winter (I don't drive it all that much) and now in summer the air conditioning has a very weak air flow -- doesn't cool anything. I'm sure it's in the blower (last oil change guy said as much) but I'm afraid a dealer/service person will charge me an arm and a leg to do something radical. Just around 115,000 miles; no other mechanical issues ever.

I'd like an idea of what exactly would have to be done if it's just a blower issue. A dealer currently has the vehicle and will come back to me tomorrow with some kind of diagnosis/estimate. Can an independent mechanic work with blowers? How do I know any estimate will not be ripping me off?

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    Welcome to the site. What is your question?
    – Zaid
    Commented Aug 12, 2015 at 19:14
  • I'd like an idea of what exactly would have to be done if it's just a blower issue. A dealer currently has the vehicle and will come back to me tomorrow with some kind of diagnosis/estimate. Can an independent mechanic work with blowers? How do I know any estimate will not be ripping me off?
    – S. Cross
    Commented Aug 12, 2015 at 19:27
  • Is it a constant, low speed regardless of what fan setting you try?
    – Zaid
    Commented Aug 12, 2015 at 20:03
  • This site doesn't address matters that are highly localized such as cost estimates or independent mechanics' capabilities, so we won't be much help in those regards. What we can help you with is the technical part - is it reasonable to say that the blower needs replacement, could something else be the reason for low air flow, etc.
    – Zaid
    Commented Aug 12, 2015 at 20:51
  • This is a constant, very low air flow. The slight flow from the AC feels cool, so the AC is probably not the problem; the defrost took nearly an hour (no scraping) to remove Minnesota frost from the front windshield. I'll know more on August 13 when the service tech gets back to me. The BIG question then will be whether it's fixable at a reasonable cost for a 13-year-old vehicle.
    – S. Cross
    Commented Aug 12, 2015 at 22:20

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One common failure point that is often overlooked is the final stage resistor. This part is responsible for controlling the speed of the fan blower (which is why I asked about the fan speed operation in the comment).

As for the fan blower itself, it is a mechanical component that doesn't fail as easily. Unless the motor is part of the blower unit and the brushes have burnt out I don't see a reason to change it. However, one possible reason for low flow could be the accumulation of dust or dirt that is limiting the fan's ability to throw air.

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If you try the different stages of the fan, how does the flow change?

The stage resistors are responsible for the intermediate stages by, well, putting resistors in the line. But the highest stage should always work. So, if there is a problem with the intermediate stages, that resistors would be the first part to check.

If you increase the stage, does the flow in general increase? May be to you hear the fan spinning faster / the whole thing gets louder? Then the air flow may be blocked somewhere. Check / replace the filter of the ventilation system. Once, I also noticed that the highest stage was louder, but didn't develop more flow than the stage below. The filter was very clogged.

Just these days, the performance started to drop again. This time, I found these in my filter together with lots of residues from their owner: enter image description here

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  • You'll get this stuff in the filter if you are lucky (and have a filter), otherwise your evaporator is going to be packed full of dirt and viscous debris that is a pain to remove.
    – masospaghetti
    Commented Nov 29, 2020 at 21:22

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