Technical How to change heater control resistor

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Technical How to change heater control resistor

ittam

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In my Stilo Multiwagon 2007, the vehicle's inside heater stopped working some time ago. Well, I managed to change (with the help of one of the Guides) the 4-step heater controller, which did not solve the issue. Now, I think that the issue has to do with the heater control's resistor which according to my knowledge is there also under the cover of the control panel. But I cannot find any guide on how to change the heater control's resistor, and any other related relevant information. Has anyone any experience of this with Stilo? - Any help greatly appreciated.
 
Yes, it controls the fan speed with 1,2 3 and 4 speeds - so, not related to climate controlling.
The fan must works on 4 position high speed even if the resistor pack is broken.
 
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Thanks, this link is very useful, and also more generally so, due to presenting all parts of the Stilo very illustratively.:)

[However I still need to find the location of resistor, from the complexity of the demonstrations of the parts; there are so many categories and their subcategories. Obviously it is to be found from there with some patience.]

Actually, I already found its location in here:
https://eper.fiatforum.com/en/Cliche/Detail/F/F/STI/2C/501/1/0/0/SubSubGroup/51740762/4

And it is part number 9 in the drawing.
 
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The fan must works on 4 position high speed even is the resistor pack is broken.

According to other source of knowledge (only available in Finnish language unfortunately), the broken resistor is typical the reason for why heater controller stops working. Do you have, some first hand knowledge (i.e. your own direct experience) that the fan works on the speed 4 even if the resistor is broken / removed? Or where are you getting this information?
 
According to other source of knowledge (only available in Finnish language unfortunately), the broken resistor is typical the reason for why heater controller stops working. Do you have, some first hand knowledge (i.e. your own direct experience) that the fan works on the speed 4 even if the resistor is broken / removed? Or where are you getting this information?

From eLearn schematics. N85 is the heather fan motor, O30 is the resistor pack, H81 is the five positions comutator.
T inside O30 is thermal fuse for protecting against fire. At key on at pin 1 of N85 you have +12 and at pin 2 of N85 is ground ( it comes from C16 ) if H81 is on 4 position dont care about rezistor pack. On 1,2,3 position of H81 the ground comes through one of the resistor pack and thermal fuse. Pin 1 of O30 go directly to pin 2 of N85.
If thermal fuse is off ( broken) N85 dont rotate on 123 positions but it works on 4 position.


ScreenHunter_138 Oct. 27 08.47.jpg
 
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According to other source of knowledge (only available in Finnish language unfortunately), the broken resistor is typical the reason for why heater controller stops working. Do you have, some first hand knowledge (i.e. your own direct experience) that the fan works on the speed 4 even if the resistor is broken / removed? Or where are you getting this information?

This gives probably the best FIAT Heater fan information on here


It's a 199 punto.. But the technology is very similar
 
From eLearn schematics. N85 is the heather fan motor, O30 is the resistor pack, H81 is the five positions comutator.
T inside O30 is thermal fuse for protecting against fire. At key on at pin 1 of N85 you have +12 and at pin 2 of N85 is ground ( it comes from C16 ) if H81 is on 4 position dont care about rezistor pack. On 1,2,3 position of H81 the ground comes through one of the resistor pack and thermal fuse. Pin 1 of O30 go directly to pin 2 of N85.
If thermal fuse is off ( broken) N85 dont rotate on 123 positions but it works on 4 position.


View attachment 432548

Well, obviously you have deep knowledge about the electronics behind the fan system, and I have no doubt that what you say is true. Thus, thanks for your expertise. However, the case is now that my fan is not operation at all, not even with fan speed 4. The issue must be therefore somewhere else, I assume. Any ideas about this?
 
This gives probably the best FIAT Heater fan information on here


It's a 199 punto.. But the technology is very similar

Yes, this is now also useful very information for me together what has been given above already. I am approaching now the dismantling phase of the parts related to the fan motor and the control resistor. What are the odds that the fan motor itself is broken?
 
More likely a melted connector

Do you mean the one that is attached to the motor or what the connector to be more specific? - And in addition, I would like to ask about if there is any simple way of making sure if the fan motor is still working / not broken?
 
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Do you mean the one that is attached to the motor or what the connector to be more specific? - And in addition, I would like to ask about if there is any simple way of making sure if the fan motor is still working / not broken?
I had all of this on a 188 punto

I removed the Fan motor and connected it direct to the battery 12 volt, it ran fine 🙂

There was heat damage to a connector

The Resistor unit gets HOT in use.. Finding heat damage there is Not unusual 😉
 
I had all of this on a 188 punto

I removed the Fan motor and connected it direct to the battery 12 volt, it ran fine 🙂

There was heat damage to a connector

The Resistor unit gets HOT in use.. Finding heat damage there is Not unusual 😉

Thanks, now it is getting clear to me what are the steps to find out where the issue locates!
 
Today I had time to start examining the issue and I got access to the resistor and were able to remove it and installed the new one. However, the issue did not get solved. Then I started to examine with multimeter (or basic tester) if their is electric current (12V) in the electrical connector but could find any. Also, I could not find electric current in the electrical connector for the fan speed connector. Is this now hinting that the issue must be related to a fuse? I attach the image of the engine compartment fuse box. If the issue is with a fuse, can anyone say which one of those in the attached image? And can I change the fuse on my own - and if so how to do it?
 

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Did the fan run ok from the battery?

If the fan is Dead.. That could have damaged a fuse😉
I did not detach the fan (motor) itself, and could not test it (yet). Actually, it was quite an acrobatic task for me even to change the resistor; for I am lengthy man (193 cm) and in addition my knee-joint is recovering at the moment from an injury. But as you instruct me to test that yet, I will have to do it. I will let you know when I know. Thanks for caring to reply.
 
Today I had time to start examining the issue and I got access to the resistor and were able to remove it and installed the new one. However, the issue did not get solved. Then I started to examine with multimeter (or basic tester) if their is electric current (12V) in the electrical connector but could find any. Also, I could not find electric current in the electrical connector for the fan speed connector. Is this now hinting that the issue must be related to a fuse? I attach the image of the engine compartment fuse box. If the issue is with a fuse, can anyone say which one of those in the attached image? And can I change the fuse on my own - and if so how to do it?
12 volts comes directly from battery through F8 = 30 A and relay T8. At key ON the T8 is actuated from key contacts through F31 ( under car dashbord )

sulakerasia2.jpg
 
Today, it took a whole day from me to get the issue fixed - to disassemble the fan motor, test it and go to buy new one and assemble all again. First to varesecrazy, yes I detached the fan motor, and like you were suspecting, the fan motor was the only thing broken in the fan system. Fuses were all ok, and even the old control resistor was ok (though I replaced also that with the new one like I told earlier).

It was tricky thing to install the fan motor again, firstly, for the lack of space there. But secondly, after having tightened the screws, the first trial with the fun made some noise, for the impeller of the fan got rubbed against its nest somewhat for some reason. Thus, I had to detach it again and examine the reason, very frustrating. Eventually, I enlarged the screw holes a bit in the body part of the motor and put small washers to prevent the impeller from getting too deep into its nest. Adjusting the position a bit with the help of larger screw holes, I was capable eventually of making fan work without extra noise from being rubbed inside its nest. Now, my fan indeed works perfectly, just well in time - for tomorrow here in Finland weather forecast is telling about abundant snowing and weather getting much colder in coming days. So, heating is needed really now. I want to express also special thanks to aschiuta for sharing very deep knowledge of the electric system related to the fan. It helped me in giving the proper foundation for electric system behind the fan. I really learned something new about this aspect of the cars, and learned to fathom the issue also from the point of view of car electrical diagram.
 
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