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Removing hair dryer heating element Answered

Request for help:  Does anyone know how to remove the heating element from a hair dryer to have it only blow cold/cool air?  I've opened it up and there are a lot more wires than I expected.  I have just enough electrical knowledge to be a little bit above dangerous, so I thought it would be best to ask for help.  Thanks!



1 year ago

Thank you I needed a portable car blower for a project and the info was very useful... 12v is ok 20 would be better. Hate to hi jack, but any ideas anyone?

Blower for these big air matress things...
They are available for mains power, car 12V or even as cobined units that work on all.

thanks! i ended up running the blower fan directly of my ryobi drill. One battery lasts about 3 melts.

I guess his project was a bit different to the original...

I have one too and found the perfect blower: Cpap machine ;)
You know these breathing machines that people use when sleeping - sometimes you get them dirt cheap, usually when the owner died....
Airflow can be regulated with a push of a button and stores the last setting, what more can you ask for....

Yes i agree you. it release very hot air which is harmful for hair...........But i have no idea about that

Be careful. Don't attempt to do this.

The simple answer is that you can't remove the heating coil and have the dryer blow only cold air. The coil acts as a resistance and drops the voltage to the DC motor to something around 12-20 volts. If you remove the coil or short circuit it in some way to take it out of the loop you will be supplying 110 volts across the bridge rectifier before the DC motor. This will likely cause to rectifier diods to melt or the DC motors to short circuit and burn. There is is no recovery from this. It will happen in an instant so don't try it.

Also there is no way to put another resistor in there instead of the heating elements. As the resistor will generate just as much heat as the coil already does in order to drop the voltage to what the DC motor can handle.

You will have to find a small AC-DC transformer that gets the 110v and converts it into 12V and then connect that 12V to your DC motor and only then you can remove the coil and put the transformer in its place. The transformer will get a bit hot but will be negligible.

The type of hair dryers that can blow cold air use motors that can be connected to AC voltage. Which are more expensive. The cheap hair dryer use the coil as a way to reduce the voltage for DC motor.


5 years ago

I did that once and when I tried switching the thing on afterwards, it gave up the ghost. It's possible (in my very limited understanding) that the heating element serves as a resistor, that cannot safely be removed without replacing it.

I'm no electrics wizz, so take this for what it's worth. I'm sure someone will be along to help you.

this sounds reasonable. since the dryer won't know that you took the coil out it's going to try to still supply juice to the coil. without the resistance of the coil it's going to cause problems.

if you could find the resistance value of the coil, you might be able to put in a resistor of equal value that wouldn't heat up, or at least wouldn't heat up in such a way that it would heat up the air.

though, they do make hair dryers that have a cold setting...and your dryer's switch block looks a lot more complicated than the normal on/off hi/lo type

The "cooll switch" some blowers have actually blows warm air.

From what i heard, the heating element works as a resistor which reduces current, while a bridge rectifier changes the AC to DC for the 12v DC motor.

Easiest way I found is to cut all wires going to the motor (and remove the heating apparatus) and wires from the AC cord, then solder wires to the motor, and connect them (with whatever suitable switch you want to use) to the yellow and black wires of the HD connector of any old computer PSU (not while it is one), jump the green wire and black wire in the ATX main power cable so that it will turn on. That supplies 12V DC to the motor. Note that blower is designed to blow towards the back of the motor where the wires are.

Or you could just buy one of those 12v Marine bilge blowers for a little bit more (choose the quieter models).

Still the dryer couldn't have the motor and heating coil in series or the motor would have never started . Hmmm just thinking out loud......if parallel, it'd still show up as some resistance in the circuit, but that;d be small. Hmmm, It also looks like, on the slider switch, that one setting has red/black opposite each other, and the next setting has them reversed ! There has to be another resistance or some other way to liimit power to the coils for medium and low heat settings.

Thanks. I was hoping for that to make sense.

since the dryer won't know that you took the coil out it's going to try to still supply juice to the coil

That is a great way of putting it.

Using Jack's method above, the motor reads about 13V. Could I just wire a simple switch and an AC to DC adapter (wall wart type) to the motor? Like the ones pictured at the top of this page:

If that would work, I'm thinking that I would select one of the 12VDC adapters or the 15VDC one. How can I figure out which power output to choose?

Thanks for all the help.

The blower motor there looks like a permanent magnet DC motor
and just based on its size and appearance I am going to guess that motor would want to be supplied with something in the range of 6 to 24 volts DC, if it were being powered by a DC supply.

Moreover, I am going to guess that the way this hair dryer is wired, is that that motor and its bridge rectifier (4 diodes) are wired in series with one of the heating elements, so that most (say 90%) of the mains voltage (guessing that is about 110 VAC where you live) falls across the heating element, and a much smaller fraction (10%) falls across the bridge rectifier and motor.

A way to confirm this hypothesis would be to solder two sense wires across the motor.  Then put the hairdryer back together, feeding those  sense wires out to your voltmeter.  That way you can look at the DC voltage across the motor, while the hairdryer is running.  I am guessing the voltage across the motor will not be higher than about 20 VDC.

Another way to do this, is to just start by assuming my guess is correct, then seek out a new DC supply for the motor.  I mean try to find a DC supply, like maybe an old computer power supply, or a DC adapter, or power brick, or whatever you've got in your junk box, that looks like it could supply between 6 to 24 volts DC, at a current of maybe 1 or 2 amperes.    Then you can just directly connect that supply to the motor, and see if you can make it run at a speed that both you and the motor are happy with.

Also thought I'd mention:  suggestions to replace the heating element with a resistor are naive. Why?  Because a resistor would dissipate just as much power as heat.

So I think you're going to be looking for a replacement power supply for that blower motor. Like I suggested before:  6 to 24 volts DC, at a current of maybe 1 or 2 amperes.

Then you put it all back together, without the heating element, and I think that will do what you want:  blow room temperature air, and consume less electrical power.