Heater fan / blower resistors

[tweetdriver63]

I've moved the posts about the resistors from Tweet's blower motor thread as there was some useful information and pictures.


I had to replace the burnt out blower motor resistor, so I ordered from Dave Bean. I got the only one in stock. It's not exactly the same as the original one, though. The connections and base are identical, so I'm thinking it's just a different version. It's the meat of the electronics that looks completely different, and the numbers imprinted on the side.

The original has the numbers : 09-24894 0093 on it, while the new one has: 09-24894 7073 on it. It also has a lot of white powdery stuff on it, which I believe is corrosion. you can see that in the pictures. Will that corrosion hurt anything? Is this the right resistor?

[Doug]

is that just dielectric grease or similar covering the solder joints?

that much white is not just corrosion--it is something put on as a protectant

[donsladek]

Tweetdriver63 wrote:

The original has the numbers : 09-24894 0093 on it, while the new one has: 09-24894 7073 on it. It also has a lot of white powdery stuff on it, which I believe is corrosion. you can see that in the pictures. Will that corrosion hurt anything?

I'm betting the white material is a ceramic type cement (such as Sauereisen) used to keep everything stable.

Good find on the motor, I wonder if the resistor came out of someone else's parts bin also?

Don Sladek

[dermotbell]

My heater fan has lost the slowest fan speed (Speed 1), 2-4 still works.

I had a read of this and think this suggests this is most likely a resistor? Is this on the fan?

I know from bitter experience on an Excel that this could be the resistor on the fan itself, which of course on an Excel was on the drivers side so I had to take off the whole dash!

Any master electricians or Geoff got any ideas.

Thanks in advance.

Dermot

[dermotbell]

I have found the electrical diagram and it looks to me as though if only Speed 1 has gone then it must be the resistor which I am guessing is mounted on the fan, which means fascia out job which does not look as daunting as the Excel, especially as the blower unit looks easy enough once I have the fascia off.

This will give me something to do when I am unemployed in August.

Dermot

[martin_bailey_1]

Dermot,

No need to bother taking the fascia out !

Take a look at this thread viewtopic.php?f=37&t=14664&p=194429#p194317 which details my investigations/corrections to my partially working fan.

As you'll see from the photos .... the resistor pack is mounted just behind the glovebox ....... easy-peasy !

Cheers,

Martin.

[dermotbell]

Martin

Many thanks that will save me a lot of effort, time and money in the swear box!

Nice to see Lotus have made this job a bit easier compared to on the Excel.

I am guessing that if as I suspect one of the resistors has gone the next question will be where the hell do I get a replacement? Is there a parts cross reference?

Cheers

Dermot

[dapinky]

I am guessing that if as I suspect one of the resistors has gone the next question will be where the hell do I get a replacement? Is there a parts cross reference?

If you can find a supply, can you let me know as well - mine only works on 3 and 4

[rip]

Most of the electrics are GM.
Hopefully you will find a GM part number on the resistor board itself when you remove it?

[dermotbell]

It'll have to wait a week as I am away on a course and I don't think the missus will do it for me while I'm away.

Dermot

[GeoffSmith]

Did anyone get anywhere with this? Ron (McJR) also has a broken one.

[maz_r]

Is it anything like this??

Never seen the Elan original part, looks similar though and dates look similar too......

[GeoffSmith]

Something like that Martin, but probably no cigar. I've already trawled through all the pictures of blower motor resistors on Rockauto and nothing comes close I'm afraid.

Looks like the individual resistance values are all about one ohm at a maximum current of ~3A so it should be possible to replace them with some resistance (constantan) wire or power resistors.

PS Why can't you buy Naval Jelly any more - used to be great as a flux for soldering constantan wire - guess the H&S crowd don't like people playing with phosphoric acid any more.

[GeoffSmith]

Look at the Group buy.

[wayne]

Not been able to cross reference the number on the side but maybe someone else will have more luck.

Fan resistor 2.jpg

Fan resistor 1.jpg

some more info here: viewtopic.php?t=12019 last part of the number seems to vary? maybe a serial no??

[GeoffSmith]

Tweetdriver63 wrote:
I'm betting the white material is a ceramic type cement (such as Sauereisen) used to keep everything stable.

Correct Don

09-24894 is obviously the part identifier and the rest is probably a batch or serial number. I've trawled through all pictures of Rockauto's heater resistors and haven't found anything close. I've also been in touch with a company in the UK that repairs them and they don't recognise them either. They could be Japanese I suppose.

Anyway, as best I can tell (the constantan wire is heavily corroded so it's based on measured values and length/csa of the wires), the resistance values are 0R3, 0R7 and 2R4 which give 0R3, 1R0 and 3R4 at positions 3, 2 & 1 respectively. The power dissipation of these little buggers is enormous (up to 20W!) and the two smaller ones glow red hot - they are cooled by the air coming from the fan. I think the heat, vibration and increased load current as the fan motor ages (and corrosion in the UK) are the reasons for them failing.

I've knocked up a replacement with 2x 0R47 in parallel, 1R0 and 2R2 resistors for RonJR (see below) and it works well, producing very similar fan motor currents. The resistors do get very hot so I've used some aluminium to help dissipate the power - in still air they would require a pretty substantial 1°C/W heatsink to keep them around 100°C but the forced air should keep them cool enough.

HeaterResistors 50W front.jpg

HeaterResistors 50W back.jpg

This allows me to accurately specify the replacement coil resistors for the group buy.

[saska]

Geoff I think there may be 2 different resistor units. When I collected a windscreen from Junks I also got one of the blower boxes which had fan motor and resistor in it. Think LEC bought the rest of them.
I put the fan in the S2 along with the resistor and it didn't work on position 1 -- can't remember which other postion it didn't work at.
I then put the original (old) resistor back in and it worked fine.
The SE has a 4 position heater control whereas the S2 has a 6 position.
Could it be there are different resistors for 4/6 controls?

[Brit-Car-Nut]

Tony:
My parts guide shows different part numbers for the housings, but the same numbers for the fans and resistors. It is possible that the low speed resistor in the replacement housing was damaged, thus the lack of low speed. The part number for the resistor is A100P6033S and it shows as being available for 20.42 which is in line with the price for similar resistors in the US...

For those in the US, Dave Beam has one for $45.00 (Remember, 20 pounds is $35.00 and they have to pay for inbound shipping). If you call them, tell them I sent you so you get that price, otherwise it is $50.00. I know it isn't a lot off, but that is my cost as a reseller. Sometimes, the prices have very nice discounts.

[GeoffSmith]

Tony, I was aware that there were 4 and 6 position heaters (LEC got a load of these but not any blowers from Junks), but was only aware of 4 position (plus off) fans and like John, I can't see why they would be different. I think John is right that the resistor pack was u/s - depending on which resistor burns out determines how many fan settings don't work. If you still have the suspect one, I hope to have some replacement resistors available soon - see the group buy.

[saska]

but was only aware of 4 position (plus off) fans and like John, I can't see why they would be different. I think John is right that the resistor pack was u/s - depending on which resistor burns out determines how many fan settings don't work. If you still have the suspect one,

I couldn't see any reason (I like John checked the parts manual) so you're both probably correct. I was just concerned that you made a bunch, sent them out and then found they didn't work.
I'll see if I can dig out the one that didn't work and have a look at it. They only take 5 mins to swap.

I hope to have some replacement resistors available soon - see the group buy.

Yes saw that. Nice one.