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How to test a laptop cooling fan (to determine if the cooling fan is clogged or not.) Would a wind meter work?

Hi I repair laptops and I have had so many customers bring laptops in latley where the cooling fans are clogged. One recent laptop that was brought to me was 100% clogged with dust, (dust thickness was uniformly 1/4" thick) and caused the cpu to overheat.

I was wondering if anyone came up with an accurate method to measure if the fan is clogged or not? I have had times where I put my hand over the side fan and felt air blowing, but ended up seeing a 50% clogage (or more). So clearly an accurate method is not just seeing if the fan is blowing or not, because even though it may be blowing out some air, doesnt mean it doesnt have a major clogage.

I recently saw an eppisode of "Holmes inspection" (home improvment tv show) and they used a wind meter to see how poorly the A/C system was working in the house. They made the repairs then tested it again and they saw like a 30% increase in windspeed (after all repairs were made). That made me wonder if a wind meter can be used for a laptop to see how much air its pusing out the side vent? I am sure the air levels would varry per manufacturer / model but it has to be more accurate then just feeling the air with your hand I would imagine. Did anyone ever test this or know if a wind meter would even measure the air pressure that the internal fan blows out?
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hydrive1902
Asked:
hydrive1902
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4 Solutions
 
PhilonatorownerCommented:
A wind meter will not work.  They generally are measured in CFM or cubic feet per minute.  A laptop fan won't even push one cfm if it was clean.
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PhilonatorownerCommented:
There are programs out there that you can use to monitor the fan speed, I suppose you could boot to one of these on a cd and see if the rpms are lower than expected but, that wouldn't help the situation where the fan is at the correct RPM and there is a chunk of dust blocking the vents.

I have a roomba and these units collect dust in places other than the dust bin.  Using a shop vac to clean the dust works ok, compress air cans works a little better, but to get all the dust out and make it look like new I give it a blast with my air compressor (make sure it is dry air).  Maybe that is a service you could offer in a routine cleanup vs taking off the front cover?
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web_trackerCommented:
As you both know servicing laptops many times the dust is so thick between the heat sink and fan that you can litterally pull out the dust similar to the lint you get in the clothes drier. No amount of blowing either with a can of air or air compressor will remove this dust and the system will need to be disassembled. My general rule of thumb is if it is over heating and blowing out the dust does not solve the over heating problem then the system needs to be disassembled to remove the dust. I agree if there was some way to test the system to see how clogged it is this would be a valuable tool.
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web_trackerCommented:
Definitely using a program that monitors cpu temperature and fan speeds may help to determine if it may be clogged up. But letting you know the percentage of clogged up would be a little difficult to determine. Obviously if the system will not boot up to windows due to the over heating problem then it is already too clogged up and will need to be disassembled to be cleaned out properly.
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PhilonatorownerCommented:
@ web tracker- I can tell you have never cleaned out a pc with an air compressor


A system monitor program could detect elevated sensor heat and that could lead you closer to a fuzzed up fan.

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web_trackerCommented:
Philonator, obviously you must not have successfully cleaned out laptops that were clogged with the lint either, or you never dissassembled laptops clogged with lint to know what I am talking about. If there is lint similar to that which comes from the drier between the heatsink and the fan, you can not blow this out using an air compressor.  There is no place for the lint to go, when you are  if you are using the air compressor to blow out the dust.  The only thing the air compressor will do is potentially break the blades of the fan (if the air pressure is too high) or it could damage the fan by causing the fan to spin up too rapidly. I cleaned several pc with an air compressor, but laptops are a little more sensitive when you are using an aircompressor to clean a laptop. Due to the way the heatsinks are designed on many models of laptops, often dust accumulates inside the pc between the heat sink and fan, using the aircompressor would only be ebeding the dust further into the heatsink.


One other way to tell if the system is accumulating too much dust is if the fans are running at full speed all the time, but this is not really that effective if the fans are so clogged up with dust that the fans can not run at full speed. If the system is not fully clogged with dust and lint, you can definitely use a can of compressed air or an air compressor if you can adjust the air pressure and ensure there is no moisture in the air blown out by the compressor.
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web_trackerCommented:
Speed fan... is an application that you may need to use and install to monitor Cpu temperatures. It can be downloaded at:  http://www.almico.com/sfdownload.php
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nobusCommented:
afaik you have only 2 options : clean the fan or replace it (and the heatpaste also)
it is difficult to clean a laptop fan completely, depending on the form of the blades, with toothpicks and soft towels, but can be worth it; a completely clean fan will push up to 50-100% more air than a blown out one
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Dr. KlahnPrincipal Software EngineerCommented:
It is difficult to determine whether a heat sink is clogged by checking airflow through the heat sink from the outside.  Many laptop fans run only on thermal demand to save power.  No air moving through the heat sink may only mean that the thermal sensors have not reached the fan turn-on temperature.

In my experience, there's no way to determine whether a laptop heat sink is clogged other than to open it and see.  Once a laptop is opened, there's nearly always some amount of crud on the heat sink that must be removed.

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hydrive1902Author Commented:
Thanks for the info everyone,

I have done MANY of these and I totally agree with web-tracker in saying if it is a thick dust (like the lint that comes out of the dryer) then there is no ammount of air that can push that stuff out. Lint is built up fiber by fiber, but the fibers are so large collectivley that if its at that level, you have to physically open it up and remove the lint. Normal dust however will shoot out by using an air compressor. Actually I believe its better then compressed air they sell in stores because the compressed air they sell in stores shoots out CO2 if you tilt the can or spray it too long, which can cause the chips to shrink / expand and cause obvious intermittent issues.

For the average user I find that an air compressor is the best tool. I also have a DV9000 (suseptable to overheating) and every few weeks I give it a few squirts of air from all vent ports, and it does a super job of removing the dust. Sometimes I can actually see the dust shoot out. Never ever damaged a fan yet, allthough once I cleaned a PC out that way and the dust did get into the graphics card fan, which caused it to overheat, but I reflowed the card with hot air and its been running fine for nearly 2 months now. I have done I would estimate 50 systems (laptops and pcs) with my air compressor and that is the only time any damage occured, it was an oversignt on my part because if I noticed the graphics card had a fan I would have made sure I cleaned it. Didnt realize till it was too late (it died an hour after I cleaned it) but like I said I did fix it so no harm done :-)

If the fan is super packed I use a q-tip and isopropyl alcohol to clean the blades, that works great and evaporates almost instantly so no liquid gets in the motor.

I noticed it seems like certain blankets and carpets give off that heavy lint fiber, so I always tell people not to put the laptop on a blanket or on the ground direct, but to place it on a flat surface or a tv tray so the fibers will not get sucked up into the fan, because its the carpet and blanket fibets that cause the lint blockages.

FYI figured I would mention it isnt just a regular air compressor I use, I purchased it specifically for electronics cleaning. It has many filters as well, it has a particle / liquid filter to pick up debris soon as it exits the compressor. From the compressor the air goes into an external storage tank (11 gallon) and I have two 11 gallon tanks, and they run into my office which runs to a desiccant air dryer and since that is made of metal and can give particles off I have another particle filter attached to that followed by an air regulator so I can change the pressure from 0-100PSI. . At that point the air is dry / clean so that airline runs to all my workstations. I also have the line running upstairs right by the back door so if I get a real dirty computer I can clean it outside by pulling the retractable air hoze and bringing it outside. Works awsome, worth every penny I paid for it!

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hydrive1902Author Commented:
Thanks everyone!
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