Heater Resistor Pack...

[Alistair]

Hi

For the second time I have fixed Kellie's heater blower. The first time a few months ago I don't know what fixed it - I was measuring voltages across terminals from the resistor pack, then the connector into the fan motor and it came to life.

This time I have had the whole thing in bits, the scuttle panel off, filter out and removed the fan motor itself. Put it all back together again and it;s working

There don't appear to be any loose connectors anywhere so I can't fathom it out - and can't break it again. For future reference I've taken the voltages at all terminals so I know what to expect next time it breaks (which it inevitably will).

One thing I did wonder though is that the heater resistor packs in Fords of this era are renowned for melting. When I was putting it back together and the fans were running I accidentally touched it and it was roasting (hot enough to burn finger). I notice that its location has the resistors themselves plugged into the air stream of the fan - I assume to cool it.

Question is how hot should these things get? I don't think this unit is at fault as I've seen pictures of melted ones but just wanted to check if such things should be as hot.

Any advice - as always - much appreciated

Ford (sore knuckles from working under the bonnet of a SportKa) Department

[robin]

The resistors should only be required for the slower fan speeds. At full fan speed there should be no need for a resistor - so, if the pack does burn out you can just short out all the resistors and at least you'll still have full fan speed

The resistors are supposed to get hot - they're converting some of the power that would go into making the fan spin into heat instead - a very primitive speed control design, but simple is good when it comes to cars

Cheers,
Robin

[campbell]

Crikey we are getting handy with the spanners out here in darkest West Lothian, Al!!

[Alistair]

Thanks both.

Robin - I guessed that it was meant to get hot when I realised it was placed in the flow of cold air - just wasn't sure how hot?! Seems inverse logic to me though as the cooling effect will be least when there is most resistance i.e on setting 1 with least airflow and I expect most heat, and greatest on setting 3 when with most airflow and least heat. Get what you say about setting 4 as that is normally the only setting that works when the resistor pack goes - bypassing the resistors. I'm starting to think the issue may be more with the control panel itself. I am readying myself with some wire from the fusebox directly to the fan with a rocker switch - fans on - fans off - as you say better than nothing Come to think of it I could always get a dimmer switch from Homebase - smoooooooooooth.

Cam - Interestingly enough I thought it would be a simple job to remove the scuttle panel, pollen filter and top part of the airbox to get at the fan motor, connect it directly to the battery and test. As is usually the case with these things (especially with a 1600 engine under the smallest bonnet in the world) it wasn't. Before I knew it I had half of the top of the engine bay lying around in the street and an amazing array of screws and bolts lying everywhere - then Mum arrived for tea To top things off once I finally got the fan motor out Mike Tyson couldn't have separated the connector between it and the resistor pack - so time to put it back together and head to a scrappy and cut wires! Last gasp test and it worked. Ford were bang on with their ad campaign for this car - "Evil Ka"

However, light nights are a blessing and its all back together again and I have a happy Wifey Even managed to tape the World Cup semi and just finished watching it. Should be a cracking final on Sunday - shame we're both working at T in the Park GP and WC final in one day - I'll have some job not finding out the results and watching them on replay. Where's the fingers in ears "LA LA LA LA" smiley?!?

[campbell]

Should be a cracking final on Sunday - shame we're both working at T in the Park GP and WC final in one day - I'll have some job not finding out the results and watching them on replay. Where's the fingers in ears "LA LA LA LA" smiley?!?

Yep I think you need to accept your fate, no way you are going to escape the footie result one way or another at T in the Park...it'll probably be announced for heaven's sake...GP you *might* just get away with and even if not, watching the current pack at a revitalised Silverstone has got to be worth it on Virgin Catchup no matter what!

Impressive auto sparking btw. Want to fit my new chav-tastic LED bulb set? Think it's beyond my newly-extensive skillset. Kidding. Should be here end of the week though so pop round for a laugh when you can

[Alistair]

Should be a cracking final on Sunday - shame we're both working at T in the Park GP and WC final in one day - I'll have some job not finding out the results and watching them on replay. Where's the fingers in ears "LA LA LA LA" smiley?!?

Yep I think you need to accept your fate, no way you are going to escape the footie result one way or another at T in the Park...it'll probably be announced for heaven's sake...GP you *might* just get away with and even if not, watching the current pack at a revitalised Silverstone has got to be worth it on Virgin Catchup no matter what!

Impressive auto sparking btw. Want to fit my new chav-tastic LED bulb set? Think it's beyond my newly-extensive skillset. Kidding. Should be here end of the week though so pop round for a laugh when you can

Actually come round to your thinking about LED's for the sidelights, the S's are looking distinctly old and "Power saving"!

Did they cost much? Only other challenge is changing the light bulbs on the S is like getting to a heater fan motor on a SportKa. Think it's arch liners off and all that. If I ruled the word things like this wouldn't be allowed to happen

[campbell]

Less than £4 shipped for a pair of sidelights for Elise - BA9S type sidelight bulb, similar cost for Octavia type 501 sidelight bulb but shhh don't tell Lisa I am going to sneak them in and see if she notices.

£7 + P&P for stop/tails (which I'm changing on the Elise since Kellie remarked that one is dimmer than the other...)

Here are the eBay stores I used, after much digging around to find UK based sellers as opposed to the different named but clearly same Hong Kong sellers "high quality no shipping delay best low power bulb especially for you" :

http://stores.ebay.co.uk/x-f-o-r-t-y-n-i-n-e-x?_rdc=1

http://stores.ebay.co.uk/ARGO-CITY-LTD?_rdc=1

Happy to provide moral support and hot coffee while you change yours over

[robin]

The cooling effect will be marginal anyway - the resistors are designed (well ought to be designed) to cope with the heat they produce at high ambient with zero airflow. If they needed to aid heat dissipation they would have heatsinked them to the chassis.

In fact the power drop doesn't work the way you think.

Power drop in a resistor is I^2 * R ("I squared R") where R is the resistance and I is the current flowing through it.

Assuming the resistors are done in a chain (i.e. setting 1 is all three resistors in series; setting 2 the middle and bottom resistor in series; setting 3 just the bottom resistor) then at setting 1 the current is the smallest value (fan speed is proportional to current) and even though R is at its largest, it is actually spread across three physical resistors, so each resistor is dissipating one third of the overall power drop). On setting 3, I will be largest, so I^2 will be at a maximum whilst R is the same as it was for that resistor before. So the worst case will be the heat dissipated by the bottom resistor on setting 3 I think.

Cheers,
Robin

[Alistair]

I knew my logic would become flawed at some point! Thanks Robin.

Think we have it isolated now to either a faulty ground, resistor pack or the control panel itself. I don't think the resistor pack can "come back to life" if it is blown so we are nearing an end game I think.

Just need to wait for it to break again - never would be good

[campbell]

All I can see out the window is - not a lot - it's covered in ash.

"All I can see out the window is - not a lot - it's covered in coolant."

Fixed that for ya mate

[Alistair]

Ah - needs updated I think! I'll go and work on that now!

[Alistair]

All I can see out the window is - not a lot - it's covered in ash.

"All I can see out the window is - not a lot - it's covered in coolant."

Fixed that for ya mate

There now - all fixed

[campbell]

better!

For my own part, all I can see out of the window is...cracks, all over the fecking windscreen...sheesh!