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Discussion Starter #1
I'm not going to be able to get to any repairs for a few days, or have my mechanic do any diagnostics until next week. But am wondering if anyone has any ideas what might be my problem with my A/C based on maybe some similar experience that some of you have had with your cars.

I've found a few post on the bushings failing or getting mucked up on the blower, but am worried it could be something more serious on the verge of happening.

In a nut shell, when I got in the car yesterday afternoon leaving work and cut on the A/C regardless of whether I had it set to 1 or 3 there was no more air blowing out and it was only when I cut it up to 4 or 5 that any air actually started blowing enough really feel it.

The air even on the lower fan speeds is cool, so the system is cooling it is just very quiet and not pushing much air out. Normally when the system is on even number 2 it sounds like a jet airplane with the windows up in the car, my fans normally blow. I have checked to make sure I didn't hit any buttons, and it is not on Econ, or another setting, and it doesn't seem to be user error.

I was worried at first the coolant maybe getting low, but there is still cool air coming out of the vents, just without much force. It sounds like it is obviously the blower, but am fearful it could be only the beginning so am only seeing it to cool the car initially after it sits out in the sun all day, then am suffering home with the windows down.... we're in a pattern of flash flood storms this time of year so the top going down in rush hour traffic isn't an options. My drives into work have been very delightful though, but I digress.

After I check the fuses of course, would it be worth my time to pull the blower and take a look at or blow some compressed air through the blower unit itself, or does this sound like something else.

I don't expect a full diagnostic, but am hoping something about might case rings a bell or two and someone can help me at least know were to start and possible figure out at what level I can expect this little issue to cost me.
 

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Could the cabin filter be so dirty as to blocking considerable airflow. This occurred on my Honda CRV
I totally support this idea. I remember on my 1st VW Golf III the filter was so filthy that even on high setting didn't let any air through...
And fan is worth looking at too.
 

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Discussion Starter #4
Ah... I hadn't thought about that. Same thing I recall happened in a Nissan I once had. I will look into this over the weekend if I can find a few hours to pull things into the garage. I probably need to replace it regardless, so will order a new one today and replace it altogether when I get the part. I hope it is this simple, but it seldom is...
 

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The blower has an electronic speed controller that is likely bad, although it is more common for them to go out completely (no blower at all). Could also be fan rotary switch.
 

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Discussion Starter #6
I swung by to see my buddy who works on my car when things get above my head and he seems to think it is the blower resistor, or regulator. He showed me the attached picture and quoted me over $200 for the part. I've since found it on my own for half the price, which is doable if that is what I need.

My plan is to pull the dash apart this weekend and look at the blower and this part to get an idea of what things look like. As close as I am to my mechanic buddy, I realize he is running a business and has to charge me, but if I can DIY this myself and save $100 on the parts, learn something in the process and save the 9/10 hr labor. I will do it and leave the under the hood stuff to him. Although I have not ruled out it being any of the other previously mentioned suggestions
 

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Discussion Starter #7
Well I thought I had resolved my problem, and I may have figured it out but won't know until I can get a filter. I dissembled the passenger side dash so I could get to the blower assembly and the cabin air filter and when I removed the panels I had tons of leaves and debris.

With the cabin air filter out and the lower portion of the dash off and cleaned using compressed air I ran the a/c and it worked as it should. So I buttoned everything back up, cleaned the cabin airfilter and blew out all the debris and then tried the a/c again with everything closed up and the problem was back.

I didn't have a new cabin air filter at the time, but figure that is the cheapest fix if the old one is limited air flow to the blower. I am assuming the blower pulls air in from outside through the filter and if filter is full/clogged like any other fan it will not work at optimal. So the first suggestion of cabin air filter could be the winning guess, but I won't know until I can grab a new one and toss it in.

I am hoping that is all it is and I can get away with a $30-$40 filter and not have to replace any pricier parts.
 

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head to advance auto. they are open and should have the filter
 

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do you have any pics or link that shows how to get tot the blower ? mine is doing similar and i just ordered the part .. just don't know how to get to it .. i assume under passenger side glove box ??? can you put me in the right direction
 

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Our 2001 SLK320 has a possibly related problem. On a hot day, turn on the A/C, and the fan doesn't do anything on any setting. However, from the cold air dribbling out, you can tell the A/C itself is actually working. But, in a few minutes the fan turns on and runs at whatever fan speed is set on the knob. It will also do this "delayed fan on" in cooler weather with the defroster (which of course also uses the A/C).

In this cold snap the last few days (down to 1 F, the fan motor turns on instantly.

I'm suspecting something like a relay somewhere, but find the Star Service Manual CD schematics to be unreadable/unusable.

As a PS, we had a similar problem with the power seats working "when they felt like it". That turned out to be bad/cracked solder joints on the K24 Relay. I re-flowed the solder, which fixed the problem.
 
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