The fan works fine on full speed. Other speeds packed up one by one. The resistor is visible and clearly over heated so a new one is required. I have not checked the cabin filter which may be dirty but airflow has never been an issue. It has pent 90% of its life on speed 2 - almost full load on the resistor - so no surprise it's fried.

It might be possible to access from the top but there is no certainty. There is considerable work either removing steering or the whole dash moulding so my plan is to go for a PWM controller. The potentiometer can be fitted to the original control knob but a separate switch is needed for the aircon. I'm looking at fitting a push button to the circular vent above the gear lever. There is space and it wont get switched accidentally.

More to follow when I get the components.

PS - finding a PWM that's not shipped from China is proving difficult.
Here's a good example https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=193376416750&_sacat=0

DaveMcT said:

PS - finding a PWM that's not shipped from China is proving difficult.
Here's a good example https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=193376416750&_sacat=0

Click to expand...

Have you browsed the RS Components site? Might throw up what you want, and delivery is usually next day. Push switches too.
https://uk.rs-online.com/web/

DaveMcT said:

The fan works fine on full speed. Other speeds packed up one by one. The resistor is visible and clearly over heated so a new one is required. I have not checked the cabin filter which may be dirty but airflow has never been an issue. It has pent 90% of its life on speed 2 - almost full load on the resistor - so no surprise it's fried.

It might be possible to access from the top but there is no certainty. There is considerable work either removing steering or the whole dash moulding so my plan is to go for a PWM controller. The potentiometer can be fitted to the original control knob but a separate switch is needed for the aircon. I'm looking at fitting a push button to the circular vent above the gear lever. There is space and it wont get switched accidentally.

More to follow when I get the components.

PS - finding a PWM that's not shipped from China is proving difficult.
Here's a good example https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=193376416750&_sacat=0

Click to expand...

They do get warm at around 50C in the airflow. But shouldn't look over heated

But without the airflow the thermal fuse blows. Around 200C. You will loose all speeds except max and they will brown.

common feature on a lot of cars not just Fiat.

I've taken out the steering column (twice at least) to change the torquesensor. It's really not a big deal. Remove the shroud (torx IIRC), 4 bolts and a few connectors and 1 last bolt in the joint. Make sure to not turn the steeringwheel when disconnected to prevent the wires for clockspring and airbag to break.

gr J

RS Components have some PWM air conditioning fan speed controllers at around £75 but they work on higher voltage and it's not clear the motor power they can handle.

The Panda fan motor has a 30 Amp fuse. 40 Amp controllers are £10 to £16 on eBay, so it's looking like the Chinese will get the deal.

A3jeroen said:

I've taken out the steering column

Click to expand...

I doubt it will give better access to the resistor though. Once the bottom joint of the column is disconnected and the shaft pushed away, access will not get better.

I've just looked at eLearn. Big procedure involving removing the whole fascia, which of course means doors off.

Haynes however, say disconnect the column lower joint, then the wiring plug, remove the screw and extract the resistor. They do warn that access is severely limited. (Understatement)

Might need a flexi drive for the screw. A large assortment of 'special' words will also be necessary.

Good luck.

I've no idea about access to the resistor. My Panda has the steering on the right (left that is) side But like I said taking out the whole steeringwheel and column is no biggie.

gr J

portland_bill said:

I doubt it will give better access to the resistor though. Once the bottom joint of the column is disconnected and the shaft pushed away, access will not get better.

I've just looked at eLearn. Big procedure involving removing the whole fascia, which of course means doors off.

Haynes however, say disconnect the column lower joint, then the wiring plug, remove the screw and extract the resistor. They do warn that access is severely limited. (Understatement)

Might need a flexi drive for the screw. A large assortment of 'special' words will also be necessary.

Good luck.

Click to expand...

As ever, when push comes to shove, Haynes are a waste of space. This is exactly why I did not proceed with taking out the steering column. The pedals look to be at least as much in the way and the resistor is really high up.

This YouTube shows how to completely remove the dash panels, leaving the structural steel tubes in place (the stuff that need doors taking off to remove). There might be space between the structural tubes to reach down to the resistor. Fast forward to the end to see the tubework.
https://www.youtube.com/watch?v=1-G6rwnRQFI

This is the LHD Fiat 500 and the job looks on the hard side of not easy. Put all the driver's gubbins on the way and see how it goes.
https://www.youtube.com/watch?v=MZ3vHyD-jtw

I wouldn't remove anything else to replace the resistor

you can see the bolts from underneath


if you can see them you can undo them.


not a great photo as I am try to hold a torch at the same time. Rusty but no sign of heat. 100K and the last 3 years mainly on setting 2

The resistor side of the module is easy to see through the recirc air intake. The business side on the outside of the casing - with electrical connector (one hand to push retaining clip another hand to pull it out) is about a foot too high to reach even if you take out the driver's seat and lie on your back.

The two retaining screws M6 hex or M10 hex or who knows hex are just as impossible.

the only problem is the gap is too small to get your hands in as the steering column cuts diagonally across.

I would just press the latch in (arrowed) with a long blade and use a spatula at the join red line.

other arrow is the bolt which is easy removable with a flexi drive.


with the column moved out of the way it doesn't look like a fexi drive would be needed.

40 amp PWM module ordered along with a switch for the air con. I found a seller in UK who was not saying one thing at the top of the advert and another when you dig down for their address. It's the same Chinese unit but at least it's likely to arrive this side of Christmas.

I will need to fit a potentiometer via flying leads but will order that when I can measure the resistance used on the module.

Also ordered a switch for the air con.

Re: Impossible access to the heater fan resistor now fitted

Hello,
After a great deal of swearing, I've manged to replace the resistor unit
As said in other notes this can be repaired with a new thermo fuse and or resistors, but at £7 for a whole new unit, it probably isn't worth it.
As noted removing the steering column bolt and tube does ease access, but not significantly. Removing the glove box and fan are also a good idea as this enable you to get hold of the unit to push it out.

The main issue at this point is the one screw holding it in place, it is nigh on impossible to see or get to being right up behind the footwell. But with a torch this 5.5mm nut screw can just be noted. I had to purchase a very long flexible 1/4 inch extension, with a universal joint added and then a 5.5mm 1/4 inch socket. This was the only way to get it to sit on the screw head and undo it, even so it is a faf and likely dislocates your neck too, as you try and look up at whats going on.

Once the screw drops out, dump it as you'll never is this lifetime get it in back in place

Via the removed fan you can then push the resistor down and out, then fro the footwell just about grab it, disconnect the locked connector and it is out.

Inserting the new resistor pack is similar to removal accept it is MUCH WORSE, as you have to try and find the hole it should go into, but having no way to see where that is, I shined a light in from the fan entrance to help, but it is still, right, right up at the back -further than you think it is.

With alot swearing and injuries to you hand, you will in time get it to go in.

NOTE for those with children, this maybe the time your investment pays off! As with a child's small arms and hand, they will be far better at getting their limbs into this space, you can then sit with your fingers though from the top via the fan hole and help grab the resistor, considerably easing this process.

As said before, you have no hope of putting that screw back in place so I just packed the area behind it with something fire proof just stop it falling out?


Then all should now be ok

DaveMcT said:

40 amp PWM module ordered along with a switch for the air con. I found a seller in UK who was not saying one thing at the top of the advert and another when you dig down for their address. It's the same Chinese unit but at least it's likely to arrive this side of Christmas.

I will need to fit a potentiometer via flying leads but will order that when I can measure the resistance used on the module.

Also ordered a switch for the air con.

Click to expand...

The PWM and switch (for air con) have arrived. Not bad as only ordered 6th April. The circuit board soldering looks really neat and shiny.


I've made a plate to carry the potentiometer under the fan control switch. It's 100K with switch but (as shown in advert) has a short spindle. I will need to check if it's log scale or linear then get one ordered with a long spindle.

Hello,

So this is for adding variable speed fan control?

If so, will you just put it just before the power connector to the fan or are you going for a complete replacement of the fan control on the dash?

Mine is still on order, but will be installing it just before the power to the fan

Not sure where to put the control though yet.

Thanks

I spent quite a while sitting in the car scratching my head about the best way forwards. First idea was to put a speed control knob somewhere, maybe in that little grille vent hole above gear lever.

I then took out the speed control switch. It's held by three peg catches so have to be very careful to not snap any off. But once it is out you have a big muli-connector with 12V in, speeds 1 to three and speed 4 which puts 12V direct to the motor. There is a second connector which controls the aircon and puts the warning LED in the middle of the fan speed knob.

The motor speed is "easy" enough suitable spade connectors can plug into the big connector with no damage or changes needed. One delivers power the other goes direct to the motor. The PWM has 4 connectors. Power in Power out and two negatives. The negs are just connected to earth.

The aircon just needs an on-off switch with LED.

Simples?
Unless you want a random volume control knob and switch stuck somewhere on the dash there's a problem. I wanted it to look OEM and that's where the "fun" starts.

Fan speed control knob
Fortunately the OEM switch is turned by a standard size 6mm D shape spindle.
(1) We need a potentiometer to match the one in the PWM which can be turned by the knob. Alternatively, make a spindle extender (which was my choice).
(2) We cant leave the pot floating but removing the OEM switch leaves lots of space. I made an aluminium bracket so the pot spindle just plugs in as the OEM switch did.

Air conditioner switch
How hard can the Aircon switch be(?) Just pop out the little circular panel vent and away you go. BUT it's not a simple flat panel, the hole is an angled sleeve. You can't just use washers under the switch (25mm OD with 16mm bore) because you need another behind.

Looking elsewhere. Unfortunately there are ribs and screws underneath or no access or the location looks crap.

The 100HP switch panel will fit and it has an extra switch (front fogs) but the connector is tiny and the Dynamic has fewer wires in it's connector. Good luck picking up the extra one. And that's if the 100HP steering switch is compatible.

The investigation continues.

Would it be possible to wire this ASR switch up to aircon?

Or would it pose the same problems as the 100HP switch panel?
This one's available on eBay.
LED is built in, just needs a dab of tipp-ex to cunningly amend ASR to A/C

I looked at fitting my push button switch to one of the blanks. However the switch block is not intended to separate. I dont have a spare to butcher.

The block you have would be an elegant solution. You will need the associated connector so you can splice that to the car's wiring and break out the ASR wires. The switch console operates via the body computer. The air con control is via a relay on the fuse box. You will need a latching relay to drive the air-con relay. You might be able to replace the air con relay with a latching type.


I've tried to fit my switch to the little air vent and failed. The switch fitted with careful trimming, but the top tag snapped when I tried to remove it from the car. It's looking like a job for Dremel.

Leave the aircon button In place. Hide the speed control knob somewhere else, out of sight, maybe in the glovebox or under the dash.

An alternative would be to wire up some resistors to the outputs from the OEM switch to give different signals to the pwm for the speed control,

AndyRKett said:

Leave the aircon button In place. Hide the speed control knob somewhere else, out of sight, maybe in the glovebox or under the dash.

An alternative would be to wire up some resistors to the outputs from the OEM switch to give different signals to the pwm for the speed control,

Click to expand...

It's really about where you want to put the effort. You can grovel around abobe the peald and hope you can get to the job. You could take out the dashboard top (see video on YouTube) and reach down or you can try various flavours of PWM speed controller.


I thought of keeping the OEM switch with plain resistors to set the speeds but found the wires to the OEM heater fan switch connector are too short for comfort. There is very little space to splice in the wires. My method simply plugs in two male spade connectors. One for power and one for feed to the motor.

I have now sorted out the air con switch into the little thermostat vent. A multi-tool (the oscillating type) neatly cut off the plastic tube/sleeve/boss on the back side. It's no loss on the non-climate cars and it came away neatly. Dremel would be another option.

The new switch is now in place and looking great. Mine is 16mm diameter so uses large washer on each side of the panel. There are others that might just clip in without washers. I spent AGES (!) faffing with wires, because the instruction diagrams were wrong. It's not a big deal just choose your switch carefully.