Technical Heater Blower 2.8 JTD

[cjmackie007]

Hi Guys,
I have a 2.8 JTD Ducato motorhome (2003). The heater blower fan is working only on speeds 1 and 4. After research on here on here I replaced the resistor pack today and it still only working on 1 and 4.
Anyone have any ideas where the problem could be ?

 

[rayc]

The switch or the speed 2 & 3 leads from it to the resister pack?

 

[cjmackie007]

The fan still only blows on 1 and 4 as it did before I replaced the resistor pack.
I`ve been advised to check for melted wiring, but how far up the loom would I need to go.
If anyone knows of anything else it could be I`d be grateful to hear.
Thanks

 

[rayc]

The circuit is basic. A negative is fed to the switch common which feeds it down on a different wire for each speed setting to the resistor pack.
Remove the connector to the resistor pack and check for continuity from chassis to each connector in turn as each speed is selected. Check the connector contacts. As you believe the resistor pack is ok then it can only be the switch itself or the wires from the switch to the resistor pack or the connections.
Attached is the circuit for the X250 but yours will be the same or very similar as far as the switch and its connections are concerned.
N085 = motor
H081 = switch
O030 = resistor pack

 

[cjmackie007]

OK, about 6 inches of cable inspected back up the loom and contacts in plug, and no sign of scorching or melting evident !
Could it be the four speed switch is faulty ? Could I check this with a multimeter.
Should I see different volts on the resistor pack contacts depending on which fan speed is selected ?
Or anything else it might be ?
TIA

 

[rayc]

OK, about 6 inches of cable inspected back up the loom and contacts in plug, and no sign of scorching or melting evident !
Could it be the four speed switch is faulty ? Could I check this with a multimeter.
Should I see different volts on the resistor pack contacts depending on which fan speed is selected ?
Or anything else it might be ?
TIA

Yes it could be the switch. Do what I said previously. Disconnect the resistor pack connector and check for continuity to chassis on each wire in the connector in turn, as each speed is selected. You should have continuity on the wires for speeds 1 & 4 when those speeds are selected as they work. What about wires for speeds 2 & 3?
Do you understand what the switch is doing?

 

[cjmackie007]

Do you understand what the switch is doing?

Erm, no auto electrician, but I think so, the switch provides power to the resistor pack and it is that that creates the resistance to slow the speed down for 3,2 and 1 speeds ?
You say the -v/e comes from the switch, so where do I pick up the +v/e
Not sure what you meant about continuity with the chassis, sorry cant recall your wording as I can`t see earlier posts whilst replying !
Thanks for your help

 

[rayc]

I cannot be sure on your model but on the later X250 the motor positive supply is via a fuse and relay in the engine fuse box. The supply is there whenever the ignition is on. Your positive supply must be ok as it works on speeds 1 & 4.
The motor speed is controlled by the negative supply which is the battery negative / chassis.
The negative is connected to the switch common contact. Each speed position on the switch feeds the negative to the resistor pack on its own wire when a speed is selected. It is C016 in the drawing
It appears you are not getting the negative supply to the resistor pack when you select position 2 & 3.
Set your meter to ohms and connect the black lead to chassis. With the resistor pack connector disconnected connect your meter red lead to each wire in turn as you select each speed on the switch. You should be able to work out which wire is for each speed and you should expect zero ohms between the chassis and the individual contact as each speed is selected.

 

[cjmackie007]

Thanks for taking the time to reply, I will do as you say, but I am reaching the limit of my technical knowledge on this now !
If I can identify the spade connections on the resistor pack for speeds 2 and 3, would it be in order to run a separate - v/e to those two terminals ?
There is an earth connection quite close in the fuse box.
Other than that I think I`ll have to put up with it on 1 and 4
Thanks again

 

[rayc]

If I can identify the spade connections on the resistor pack for speeds 2 and 3, would it be in order to run a separate - v/e to those two terminals ?

Then you would be selecting speeds 2 & 3 at the same time and all the time when the ignition is on. This would have the effect of shorting the centre resistor out. I am not sure what would happen to the fan speed after all that.
Your best bet is to pay an auto electrician to sort it out as a fairly large current is involved which leads to considerable heat. The last thing you want is a fire.

 

[corcai]

If 1 and 4 are fine then the resistor, motor and earth are fine. Its probably burnt contacts in the switch

http://www.ebay.co.uk/itm/Fiat-Duca...650025?hash=item5694ae7a69:g:AAwAAOSw6-hYm03T

 

[cjmackie007]

Thanks for the info.
The fan switch looks to be firmly fixed in the centre dash consul, has anyone ever removed one yo replace switch ?
Any idea on proceedure ?

 

[cjmackie007]

rayc

Do you have an exploded diagam for the central dash area showing fixings please ? and how it`s dismantled
I`m struggling to get to the back of the fan control
Thanks

 

[FreeSpirit]

Hi
I was going through some of the Ducato stuff from the net I have found over the years & came across a site, a Hymer travel Forum, I had copied it & some other info to a word document regarding the Heater fan switch & the resistor from this Google Translate site - https://translate.google.com/transl...18&t=752&sid=5fc466059e476770fea7e76c2f9acdc7
As the Word Doc exceeds the 488.3Kb limit I can't upload it but above link is where the some of the original info came from. Also check the previous post from the forum if you haven't already seen it -
https://www.fiatforum.com/ducato/448166-how-remove-heater-control-ducato-04-a.html
The Hymer forum gives a description & pics of how to replace the switch.

Cheers

 

[cjmackie007]

Freespirit - Thats really useful information, Thankyou

 

[cjmackie007]

Just by way of an update - the info from FreeSpirit was very useful indeed so thankyou.
I decided to replace the fan switch as per the instructions from FreeSpirit.
The most difficult part was moving the white plate holding the three rotary switches into a position where I could access the back of the switch. A lot of manipulation is needed but it can be done.
All back together now and working nicely.