Home Brewer Heater Resistor Pack (pics)

[Tony26]

First little job on the wifes mgf was to get 1 and 2 working on the heater fan.

As you can see both coils are burnt out.



After a trip to Maplin, I made up some coils of resitor wire to the correct ohms, and soldered them in.

Not as pretty as a new one but works perfectly fine. All for about £5

[jupilerman]

What impedance are we talking about?

[Tony26]

1= 2.1ohms 2= 1.5ohms 3= 1ohms

[Pete T]

Great tip Tony!! - I'll try and remember that one!!

Think I've still got some Eureka Wire somewhere.....

[DAVIDT6DCM]

Did the same with my F's and Rover 400 Resistor pack (same both cars)as both had gone same as Tony's, the original coils 1 and 1.5 ohms are very very thin and delicate i replaced with a little bit stronger resisitor wire also, it's great to have poss 1 and 2 working on both cars again as poss 3 a little too much sometimes, Dave

[Benfinlayson]

Originally Posted by Tony26

After a trip to Maplin, I made up some coils of resitor wire to the correct ohms, and soldered them in.

Not as pretty as a new one but works perfectly fine. All for about £5

I have exactly the same problem with my resistor pack. Any chance you could let me know the spec of the wire and the lengths required for each bit. I am ok with a soldering iron so might give it a go. Did you use special solder? Will it melt normal solder as it gets pretty hot!

Cheers

Ben

[Tony26]

This is the wire I bought from maplin, I used this for fan speed two which is 1.5 ohms, just wound the wire round a screw driver, then tested using a multimeter. For fan speed 1 the wire is slightly finer, sorry I didn't measure the length of wire used was just trial and error. You can use normal solder because the coils are cooled by the fan in the heater box.

[Dave400]

Just for anyone wanting to find this...
http://www.maplin.co.uk/Module.aspx?...NTaN&doy=24m10

Based on the figures quoted by Maplin, 4.2ohms is 1 metre of wire therefore...

50cm = 2.1ohm
35cm = 1.5ohm
23cm = 1ohm

Also availble from http://www.wires.co.uk/acatalog/cn_bare.html

[KrisFX]

Hows about adding this little gem of a tip to your one-stop shop website Mr V?

Think it could prove handy for quite a few people.

[Petevick]

Originally Posted by krisxf

Hows about adding this little gem of a tip to your one-stop shop website Mr V?

Think it could prove handy for quite a few people.

its been on for a while, altho I will try and make it easier to find via the search.

[KrisFX]

Originally Posted by petevick

its been on for a while, altho I will try and make it easier to find via the search.

Ooops, now I feel silly!

[D.R.]

Great pics Tony26

Seemed to be common problem, had to replace one in a Landy £14 and in another Rover £24. If only I had spotted the DIY fix before hand

Another thread kicked off by Dr Dave uses individual resistors instead of wire:

http://forums.mg-rover.org/showthread.php?t=55979

Technozen placed a good diagram of wiring position in post 54

They are also using different ohms 1.5, 0.68 and 0.2

Q. How does your fan speed run in comparison to the original?

Also, can you use something like fire cement to keep the wires evenly spaced and prevent the coils making contact?

[Herbie]

Great !
I feel a little project coming on (1 not working) but it's the hell to reach that pack. Any hints for a LHD car, 'cos I almost broke my fingers trying to reach the area ?

[Petevick]

Originally Posted by Herbie

....Any hints for a LHD car.....

print the pictures in reverse Herbie

[Herbie]

Are you sure Pete ?

I don't know, the heater mechanics and so on....... help meee
Not soooo important if only 1 doesn't work, but on the other hand I always want it perfect.....

[Rob Bell]

Originally Posted by D.R.

Great pics Tony26

Seemed to be common problem, had to replace one in a Landy £14 and in another Rover £24. If only I had spotted the DIY fix before hand

Another thread kicked off by Dr Dave uses individual resistors instead of wire:

http://forums.mg-rover.org/showthread.php?t=55979

Technozen placed a good diagram of wiring position in post 54

They are also using different ohms 1.5, 0.68 and 0.2

Q. How does your fan speed run in comparison to the original?

Also, can you use something like fire cement to keep the wires evenly spaced and prevent the coils making contact?

Thanks for that link. Did anyone see this posting?

Thanks to this thread I had a look at my remaining resistor, the 0.25R (position III), and did a few measurements and I can see why these resistors don't last forever - they have quite tough time.

The blower must be a pretty powerful motor - about 250W (1/3 HP) at full power, so slowing it down means rather a lot of watts need to be lost, more than 60W on position III - most of it in the 0.68 ohm. By my reckoning the resistor which dissipates the most depends on the fan setting;

Position I 1.5 Ohm 28W
Position II 0.68 Ohm 46W
Position III 0.27 Ohm 47W

I could see the impact on the 0.25R because with the resistor pack out of the ducting the coil glows orange-red almost immediately, which is less of a surprise when you think of the coils as electric fire elements. I know it gets some airflow inside the ducting but I bet it doesn't make that much difference.

I suppose the 1.5 Ohm and 0.68 Ohm fail first because they have the thinnest wire and the heat makes them brittle, then the vibration simply breaks them.

The resistor pack is pretty wasteful way of controlling the fan speed but it the method used in all cars I know of.

It would be good to come up with something more elegant, but it is probably not worth the hassle.

No one has adequately answered this particular conundrum - namely the resistors being used are only 1/5th of the rating required to dissipate the energy required!

Carl had another solution using MOSFETS - might have to find out a little more about this...

[Chris T]

I think if I ever need to renew the resistor pack I would be tempted to get hold of some proper power resistors that can be bolted down somewhere.

[mercodus]

there's a thread in 'How Do I' which covers this, if you dare venture out

[partyboy]

mmm interesting thread this,ive the same problem, tho ive no fan working and no cig lighter or interior light of clock light working, are all these linked,or is the resistor pack the likely culprit for my heater and the other problems something else?

[MGFmad]

No they are not linked, I wonder if you have a wiring problem at the back of the centre console.

Resistor pack may still be faulty as a stand alone fault - you can access it from the passenger footwell - just a couple of screws and its out so you can check if the resistors are burnt out. If you need new resistors PM Technozen he will supply new correctly rated ones at a great price.

On the other faults, check the wiring at the back of the console - it may have been rubbing on something sharp or the plug connectors could be loose - has anyone been fiddling about in there recently?