Not a new topic I know, there's loads on the subject of the  fan motor resistor but,  what is the specified temperature rating of the fuse on blower motor resistor. Mines an Octavia II 2012  TDi. My fan stopped working back in May. My own tests suggested to me that the motor itself was ok as I put 12v directly to it on the bench and it ran. I let my dealer look at the car who replaced the fan. Stupid me didn't check the resistor at the time and it failed with the new fan. I replaced it and it failed again. I put an equivalent part number replacement in but I only just noticed that on my searches not all resistors stated to be for the Octavia II  have the same temperature rated fuses on them. So the question is can anyone more in the know than me tell me what the correct temperature rated fuse should be for these motor resistors.?

 

 

 

Have you got any old units so you can look at the thermal fuse and read its value ?

Firstly thanks for the prompt reply.

 

Secondly no. I threw the last one away as the resistor itself was trashed as well as the fuse. That one had a fuse rated at 216 C though and it failed last week after a weeks use. I thought it was about to fail as there was that asbestos like electrical over heat smell then click the fan went off.

 

I have just put a new resistor in tonight and the fuse on that is rated at 240 C. Both resistors are stated to be compatible for the Octavia II. I got back in the house 10 minutes ago. I switched the fan off pretty quickly a couple of minutes down the road when I went out as there was quite a strong burning smell. I wasn't going to take any chances . 

 

Surely a brand new resistor doesn't make such a strong burning smell as its running in. Also it surely is reasonable to expect to be able to run the fan on the low speed for any period of time without it continually blowing fuses. The fan itself is supposed to be new.

Is the fan running freely ? if its tight it will take more current and then the resistor would start heating more than normal, have you cleaned the pollen filter ?

 

 funny you should say that. I have just started looking through my service invoices to see when the cabin filter was last changed. I think coming onto the forum has kick started my brain into gear properly so I might over this problem sooner. Thanks for all the input. I'll get a new filter tomorrow and take it from there.

Hello I am having the exact same problem described with my Skoda Ocatvia Green 2 (2012 plate) I am on my fourth heater resistor in less than 6 months of owning the car.  I get the same burning plastic smell from inside the car. I have replaced the heater blower motor as well. I had the car serviced in July and I replaced the cabin filter. Which leads me back to the conclusion a wiring fault somewhere......??

Frustrating problem isn't it.  For me it's doubly annoying, I have a B/TEC first in motor vehicle engineering. I hoping that there is not some obscure wiring fault at play and for the life of me just can not see how one on this system could develop. The rotary knob on the control panel is merely a four position switch. The first three positions are the ones which send the drawn current through each stage of windings in the resistor. The current drawn by the motor must surely be matched to the resistors handling capacity. Yes the resistors do get hot, ****ing hot in fact, as it is a ballast resistor, but on one resistor pack I had it got so hot the cabin filled with smoke and melted the solder holding the thermal fuse.

 

I took my motor out and bench tested it direct to 12v and it ran fine. Back in the car on switch position 1 it really struggled to turn. So I have fitted another new motor and I am awaiting another new resistor to come in the post. I will see if that sorts the problem out. It could be the last resistor was damaged anyway so badly that it wouldn't let the fitted motor run at all. 

 

Stay tune for another exciting episode.

To melt the solder suggests a lack of air, a bit like putting your hand over the end of a hair driver and watching the heating element glow bright red.

A reduced air flow could be caused by a stuck flap valve. Check that air can be distributed correctly at all settings.

Also check that the air volume out of each outlet is aś expected and the same from left to right.

Everything else on this car is working as it should. When I had the glove box out and the head unit all the air flow ancillaries were functioning. The cabin filter is yet another new one. despite my car knowledge I don't work in the trade and I am damned if I'm going to pay an extortionate fee to any on line technical info database for just one spec value that I'm sure somebody out there knows. 

I know how to test various parts of the system but it's pointless doing so without having normal values to reference. This is one reason I signed up to Briskoda

Anyway, I obtained another new resistor pack yesterday. I have clicked it into its slot this morning and turned on the new fan. So far two journeys in and it's still ok.

We'll see how long this lasts.

Hello....The last heater resistor I brought off ebay lasted two weeks. I had the heating on all settings. It was running  ok apart from the smell of burning hair and plastic....and then dead.... On the previous occasion I had white smoke coming from the vents whilst driving. There is no pattern as to when they decide to fail. Coming up to winter and I am dreading it, I have the green line 2 model, it doesn't even come with a rear windscreen wiper, so much for it being tax free I can see myself in winter with a scraper and mits...lol....sorry having a rant....

There's a common problem here. Probably yet another one which if a car is taken into a franchised dealers workshop the customer will be told all kinds of bullish**, as I believe I was when the service manager insisted it was the fan at fault when it failed in May. Why then has their new fan also blown resistors. I have changed the fan myself this time so I can be certain thats it is a NEW fan. I'm sat here now with the air con control panel on my lap and my test meter and have taken photos's of the wiring and plugs in the car.

 Since the last post earlier, the resistor has blown again. I started this topic with a simple question as to what the temperature rating the thermal fuse should be, although I am grateful for the contributions to this no one has actually been able to give me an answer to the question, so I will not bother asking any more which could start me on a rant also. Being me however I am going to painstakingly go through the wiring bit by bit and nail this stupid problem. And before anyone else asks have I checked the fuse boxes, YES!

 

And YES the four position switch has got continuity on all positions. Tomorrow I am going to find the earth grounding point from the blower motor, which on many vehicles is also a common ground point for the recirculation fan motor. I dare anyone to actually to come on and tell me where this point is!

12 minutes ago, StarwarsNerd said:

I started this topic with a simple question as to what the temperature rating the thermal fuse should be, although I am grateful for the contributions to this no one has actually been able to give me an answer to the question

 

Where do you expect us to find this info, that isn't actually looking at the thermal fuse and seeing what - if anything - is written on it?

The temperature rating doesn't appear on the circuit diagrams, I can tell you that much.  I can't think where else to look except on a genuine resistor pack.

 

For the earth point, the circuits say for both LHD and RHD that it's on the lower part of the right A-pillar, but as I think the fan is probably on the left of a RHD car, I suspect it will  be on the lower part of the left A-pillar, where you'd expect really, close to the fan.

THE QUESTION COMES ABOUT HAVING HAD TWO FUSES STATED TO BE FOR AN OCTAVIA II BUT CAME WITH DIFFERENT FUSE TEMPERATURE RATINGS. The original fuse markings weren't readable.

 

There's one oddity about my cars' VIN. Although it's the hatchback the chassis code is  1Z5  rather than 1Z3. 

The correct part number for the resistor pack is 1K0959263A as far as I can see. Are you buying genuine ones, or pattern parts?  No knowing quite what you'll get if it's the latter.

Must admit that the genuine part's RRP is eyewateringly expensive at nearly £50 + VAT.

 

I don't think the 5/3 digit you refer to has any particular significance. I think it's the fourth character of the VIN that defines body type and 'luxury level'. Is for a mk1 Fabia anyway.

 

I think your plan to thoroughly inspect the wiring runs is spot on, I think you may well find somewhere where a wire is chafing against some metal and intermittently shorting.

 

I have had two Valeo ( original fitment from Skoda) , 1 Valeo from Skoda Parts, 1 Hella from ... I can't remember,  and a cheapo from e bay.

 

They've all gone the same way!

 

I am leaving this topic now. having gone through a hoard of posts on this forum it seems this is a regular occurrence. I will find this demon in my car!

Resistors usually have a current and not a temperature rating, first you need to find if the heater fan has the correct resistance and is compatible with the resistor packs you are using, did you say that it had been changed before this problem occurred? 💡

 

Its a potential divider calculation and using ohms law you can calculate how much current will be going through each resistor for each setting and determining the current rating (not temperature) of the resistors, pattern part manufacturers will save money by using lower current rated resistors, if the pack is in the airflow (I dont know your model) they may well get away with it as its being constantly cooled but certain Climatronic settings may restrict or even stall the airflow.

 

My message to you is to forget temperature and start thinking current rating, using a 1/4 watt resistor in place of a 1/2 watt one will result in it overheating and possibly failing.

Edited 1 November, 20196 yr by J.R.

@J.R. there's a thermal fuse in series with the three resistors, which are in series with the fan motor (when switched to each of positions 1-3). 

This is the Mk1 Fabia cct, but I think it's identical:

 

 

I did this,  have found the fan motor I have taken out has power rating of 320 watts. At that level the current draw is just under 30 amps. The fuse in the fuse array is 40 amps. that 30 amps is I think within the capability of a correctly installed resistor pack. I cannot find the shunt for my test meter to measure the current at the moment however I may be homing in the problem.  On checking the control panel and the resistor pack again last night, despite the fan shutting down earlier in the afternoon

the resistor pack is ok. Since its only series resistors they're easy to check. On putting it back in the car this morning the fan is working again. The problem has to be in the wiring and somewhere and want start at the motor earth point and work back.

Thank you WINO for the fuse and resistor schematic. Much appreciated. Without a workshop manual last night that is exactly the diagram I worked out and drew on my notepad !

NB the reason I wanted to know the fuse temperature rating in first instance is because on first failure after having the fan replaced in May the resistor pack itself was ok and it was the thermal fuse which failed. I replaced that and that lasted until September when I have since had a series of resistor failures.

Still not thinking straight with my head cold.

 

Yes of course a series resistor array makes much more sense, thanks for the diagram, a bit more knowledge gained today.

 

I have replaced (= shunted) no end of thermal fuses on failed equipment in recent years, my hot air gun, couple of coffee makers, a steam mop, forget the name of the latter but it was the big brand make yet if you left it plugged in on standby for more than 30 minutes it would fail.

 

In all of the above cases the equipment was better off without the dubious protection.

Ignoring fire risk...

47 minutes ago, StarwarsNerd said:

The problem has to be in the wiring and somewhere and want start at the motor earth point and work back.

 

If you do find something, please try to get a photo of the location.

 

Here is a photo of the offending fault which was causing a overheat and persistent blowing of the thermal fuses on my heater motor resistor pack. The chaffed wire is behind the metal bulkhead support behind the dash. Sorry, the photo is blurred being quite close up but the portion of bare wire which was shorting to earth is visible. The bundle of wires were strapped to this support. The short caused the fan motor to draw on more current to try and maintain its power and then overheat the thermal fuses. The resistor fuses have therefore been doing their job and prevented the wiring from burning out and causing a fire.  Wiring now fully insulated and another new resistor rheostat and all is working as it should. I now have a new spare fan and five usable repaired spare resistor packs.

 

I find a fault like this in a car totally unacceptable. I am surprised that there could be that much movement in car wiring loom when the car is  being driven, enough to make it chaffe through. This is the sort of thing I would regularly see on motorcycle wiring looms because of the harsher effect of the bikes handling.

 

Absolutely zero brownie points and a lower estimation of my local Skoda dealer workshop for not finding this fault back in May and insisting that it was 'definitely the fan that needed replacing, which they did without also replacing  the resistor pack as has turned out.

 

Job done.

Good work .