Fan switch or Resistor pack ...?

[BenF]

I noticed the other day that the first two low fan speed settings in my Mk1a actually no longer work - the full speed setting and one down from that do work fine through.

I've not had chance to check the car itself, but I've had a look through the Haynes manual, and it looks like culprits could either be the fan switch itself, or the blower resistor block apparently near the fan relays.

Is either of these a known weakness on the Mk1a?

If it is the resistor pack, I was thinking of DIY'ing a resistor pack to replace the ones that have broken, as I have some high power ceramic resistors left over from simulating an O2 sensor for my Roadster

However, I don't know what the resistance values should be - and they're not listed anywhere I could find in the Haynes manual.

A long shot - but does anyone have figures handy?

[kevin..in]

sounds like a question for Jimi

[Tony jinxy froude]

ive got one if you need a resistor pack Ben, PM me, Jinxy

[jimi]

One off my friends with a 1a had exactly the same problem, it turned out to be the resistor pack, quite hard to find it.
If you remove the glovebox there is a black thing at the back on the left hand side which goes into the bulk head. This is the resistor pack. There are 3 elements on it and you will probably find 1 or 2 broken ( its resistance wire) depending on where they are broken, it may be possible to rejoin the wire using a non-insulated crimp ( soldering won't work) and it will work OK.
It is possible to replace the wire with high wattage resistors of the correct value ( or relatively close ). They would need to be pretty high wattage, if you know the load of the fan motor you could work it out ( but I don't ) I'm guessing at least 20 watts, if they are not high enough wattage they will just overheat and burn out.
resistor pack values
between terminals
1-3 = 2.14 ohms (approx)
1-4 = 1.23 ohms (approx)
2-4 = 0.45 ohms (approx)
Terminal numbers are looking at the resistor pack socket
top left = 1
top right = 2
bottom left = 3
bottom right = 4
hth
Jimi

[kevin..in]

=D> =D> =D> =D> =D> =D> =D> =D> how did I know you would know that stuff Jimi

[Milothicus]

could these work?

they're rated for 10 Watts, and can handle 5 or 10 times the rated power for 5 seconds. the highest draw is during startup, right? maybe they'd be ok for what you (and I) need.

don't see any close to 1.23 ohms, though.

[BenF]

Thanks for the replies, and Jimi for coming up with some figures for the resistance values.

They look a little too low for me to DIY some resistor packs, so it looks like a replacement would be teh way forwards.

Tony, I'll be taking you up on your offer - ta!