Thread: Heater fan - best way to diagnose?

I'm not sure if you have electronic skills or not, but you can buy PWM speed controllers with soft start etc on ebay. there's only 4 wires to connect - two for power feed and two to the motor. The potentiometer is a rotary type, which is easily exchanged for a slider type, to fit into the same spot as the factory 3 speed switch. Most are based on a TL494CN PWM switching regulator and a pair of N channel mosfet's

To my mind it's a far more sensible way to drive the motor, because the 3 speeds aren't enough - full bore is too much and sometimes 2 is not enough. and one doesn't even blow air half the time - I think fresh air overrides it.

Anyway, that's just an option

You'll find them on ebay everywhere or you can buy a 10A or 20A kit from jaycar, which are a bit pricier - but don't be fooled by price. often the components in ebay stuff are just junk. So be aware of what you're buying.

Here's an example: uniquegoods 6V 12V 24V DC 10A PWM DC Motor Speed Controller Adjustable Variable

Jaycar 10A version : 10A 12VDC Motor Speed Controller Kit | Jaycar Electronics - nb you can add another fet and run 20A for example:
Screen Shot 2017-07-16 at 15.26.04.jpgScreen Shot 2017-07-16 at 15.25.44.JPG
20A HD version 12/24VDC 20A Motor Speed Controller Kit | Jaycar Electronics


Anyway, it's all easy to fab something like this up if you have a working knowledge of circuits. use a 10K sliding linear pot and that should fit into the existing space - or near enought to -
RA4520F-10-20D1-B5K Alpha (Taiwan) | Mouser Australia

Well I managed to get in to the resistor area thanks to my girl - she got it all undone... but what we found wasn't what I had expected.

resistorpack.jpg

So whats the deal with this? And of course the corrosion is a concern. Last time I used \ test the fans in my greenie they worked. So I guess this thing will?

I also pulled out the blower today just in case the new cars one is DOA - pitta of a job that - I would hate to put it back - so if its DOA - I am getting AMV to do it lol or LRA.
lol

blower1.jpg

OK, Electronic skills for myself go like this;

I can solder well and know a good join
I understand how some of those components work
I understand the idea of the potentiometer

The jaycar one - 30 buck no problem, as long as I have a guide to build it - no worries. The switch - same deal...

So will the 10A one do the job and if I go build it... could you or someone you know assist in knowing which 4 wires to connect to it and the switch? Thats about the only missing part of the puzzle for me.

Think I got enough of an understanding to do it?
When I went looking for the resistor pack - I was expecting a circuit like pictured below, but perhaps older parts. This round thing with wires connected is very old school to me

Originally Posted by Mercguy

I'm not sure if you have electronic skills or not, but you can buy PWM speed controllers with soft start etc on ebay. there's only 4 wires to connect - two for power feed and two to the motor. The potentiometer is a rotary type, which is easily exchanged for a slider type, to fit into the same spot as the factory 3 speed switch. Most are based on a TL494CN PWM switching regulator and a pair of N channel mosfet's

To my mind it's a far more sensible way to drive the motor, because the 3 speeds aren't enough - full bore is too much and sometimes 2 is not enough. and one doesn't even blow air half the time - I think fresh air overrides it.

Anyway, that's just an option

You'll find them on ebay everywhere or you can buy a 10A or 20A kit from jaycar, which are a bit pricier - but don't be fooled by price. often the components in ebay stuff are just junk. So be aware of what you're buying.

Here's an example: uniquegoods 6V 12V 24V DC 10A PWM DC Motor Speed Controller Adjustable Variable

Jaycar 10A version : 10A 12VDC Motor Speed Controller Kit | Jaycar Electronics - nb you can add another fet and run 20A for example:
Screen Shot 2017-07-16 at 15.26.04.jpgScreen Shot 2017-07-16 at 15.25.44.JPG
20A HD version 12/24VDC 20A Motor Speed Controller Kit | Jaycar Electronics


Anyway, it's all easy to fab something like this up if you have a working knowledge of circuits. use a 10K sliding linear pot and that should fit into the existing space - or near enought to -
RA4520F-10-20D1-B5K Alpha (Taiwan) | Mouser Australia

Originally Posted by RaZz0R

OK, Electronic skills for myself go like this;

I can solder well and know a good join
I understand how some of those components work
I understand the idea of the potentiometer

The jaycar one - 30 buck no problem, as long as I have a guide to build it - no worries. The switch - same deal...

So will the 10A one do the job and if I go build it... could you or someone you know assist in knowing which 4 wires to connect to it and the switch? Thats about the only missing part of the puzzle for me.

Think I got enough of an understanding to do it?
When I went looking for the resistor pack - I was expecting a circuit like pictured below, but perhaps older parts. This round thing with wires connected is very old school to me

I sent you a PM.

Well I pulled out the resistor for the heater from the green one - no change - still dead and no heater. Damn it!

After pulling the heater form the greenie I have decided to have it professionally done - and then I'll change the resistor over to a more up to date design

From memory my 88 runs two different fans. One in the centre of the dash does the heater and fresh air, one in the passenger footwell does A/C air.

Originally Posted by BigJon

From memory my 88 runs two different fans. One in the centre of the dash does the heater and fresh air, one in the passenger footwell does A/C air.

Thats right - two totally different systems - Aircon fans work - but seem to be an issue with the compressor or some such - so may as well get that sorted at the same time.

I'm fitting a complete new Vintage Air HVAC system all early original smiths heater boxs I could find were pretty shot and A/c was older style under dash units with various bits of moulding/ trunking. Will let you know how well it works when we gas it up. Relatively cheap I paid about $600 for unit delivered. It is different dimensions of course smaller in height and thinner but a bit wider. It will require a new center cover panel to be fabricated. But looking at numbers to repair yours if there was significant change/ repair required, this gives new modern option.