Technical heater blows fuse

P dot co dot · Sep 17, 2014

So my cars interior fan fuse (30amp miniblade) blows whenever I turn it up to setting 4

The fan sounds weaker on settings 1-3 and if I give it a little smack whilst its on setting 1-3 I think I can hear the frequency of rotations getting faster and slower (not constant).

About 6 months ago I did the interior fan fix because it was squeaky. I used a few drops of 3in1 and it certainly rectified that particular problem. Could this be a result of that?

Do I just need to replace the whole unit?

Sidelights do not come on and connectors have been disconnected to check for burnt wires but I haven't found anything.

I have mk2b 8v no air con.

oldhammer · Sep 17, 2014

The heater 'resistor couid be at fault..or wiring too it.

P dot co dot · Sep 17, 2014

Do I need to take the fan out to get to this resistor pack?

Or is it located elsewhere?

Thanks!

oldhammer · Sep 17, 2014

Have a look on the 'fan assembley..

You will see the plug going into the resistor..unplug and remove the 1 screw and it will come out..

Ziggy122 · Sep 17, 2014

I suspect that the fan is either

partially seized, or there is a serious wiring issue as a result its just pulling excessive current

The fan is held in with 3 fasteners, they vary from philips to 5.5mm hex's

The resistor pack is the common failure by eating the connectors and burning the wiring
Its literally connected to the wiring loom

This blog i made for my portfolio may show you something to look out for

Ziggy

P dot co dot · Sep 17, 2014

So here's what the wires to the resistor pack look like... It looks like theyve got a little warm.

Ziggy122 · Sep 17, 2014

the resistor pack looks fine
hard to tell tho

However looking at pin 3, it has gone brown instead of red/yellow, telling me it's got HOT

Check the plastic for heat blisters

ziggy

P dot co dot · Oct 2, 2014

Well I checked the plastic for heat and it didn't look too bad. On further testing though, those wires were definitely getting very hot when the heater was on setting 3 (setting 4 would blow the fuse).

On removing the fan and spinning it by hand I think it must have partially seized as it doesn't spin very freely.

I got a 2nd hand fan from scrappy and it all seems to work ok. The wires no longer get hot on settings 3-4 and it doesn't blow the fuse anymore. When the fan seized up it must have been drawing too much current when trying to turn on the higher settings???? So I guess that's why they look like they'd got hot.

Thanks for the help guys

Ziggy122 · Oct 3, 2014

P dot co dot said:
Well I checked the plastic for heat and it didn't look too bad. On further testing though, those wires were definitely getting very hot when the heater was on setting 3 (setting 4 would blow the fuse).

On removing the fan and spinning it by hand I think it must have partially seized as it doesn't spin very freely.

I got a 2nd hand fan from scrappy and it all seems to work ok. The wires no longer get hot on settings 3-4 and it doesn't blow the fuse anymore. When the fan seized up it must have been drawing too much current when trying to turn on the higher settings???? So I guess that's why they look like they'd got hot.

Thanks for the help guys

The resistor pack resists the flow of electricity to give you the variable speeds

speed 1 is very very resistive
2 is very resistive
3 is resistive
4 is free flowing (almost direct battery current)

Now on 3 and 4 it spinning quiet fast and pulling some amps, now stick a binding motor and hell - it now pulling more amps, which on speed 3 its resisting very much todo

Oh wait - the fuse has just said to much to much

I've tried to see if the bearings are replaceable, but i got the motor out and its sealed pretty much.... sigh

Ziggy

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