Fault with my manual heater control panel

[philscotland]

Hi

My 1995 2WD 2.5TD Bongo camper has a heater control panel that is very temperamental.
It is the old-style slider controls version, not the digital display.
Occasionally it blows at full speed, no matter where the blower dial is pointed, but more often than not, the blower does not work at all. Also, the switch for the rear ventilation sometimes lights up, but othertimes does not.
The air conditioning appears to work - I can hear the engine note change when I switch it on.

After printing off the various heating factsheets from the site, I have checked the fuses, wiring, resister pack and fan motor and they are all fine (hence why it works occasionally), so I am thinking that it must be the control panel blower dial that has a fault.

Any help would be greatly appreciated.

Thanks
Phil

[g8dhe]

Can you get at the plugs on the back of the control unit and check that they are fully in OK ?

[lazyb5]

When you say the fan motor is fine, have you had it apart and checked the carbon brushes

[philscotland]

Hi

Yes I've checked, unplugged and reconnected all the plugs to no avail unfortunately.

I haven't checked the brushes yet, partly because the blower does randomly work sometimes.

Anything else that I could check ?

Thanks
Phil

[g8dhe]

Occasionally it blows at full speed, no matter where the blower dial is pointed

Are you certain about the full speed bit ? Because that narrows the problem down a bit, if it really comes on full blast no matter what the setting then it suggests that the motor is not being fed via the resistor pack which is what varies the speed, which in turn suggests that it might be a broken wire making random contact to earth, or a problem within the actual resistor/fuse pack which you say you have checked - have you actually opened the resistor pack up an checked inside as per the factsheets ?

[jaylee]

Also, the switch for the rear ventilation sometimes lights up, but othertimes does not.

It won't if the front don't work, or isn't switched on....

[philscotland]

Quick update.
I've been outside checking a few more things following the factsheets.
After supplying 12v directly to the fan connector block, nothing happens.
With the ignition on and heater switch on, the supply side of the connector block gets 12v.

It looks like the fan needs new brushes or motor windings, or worse case completely replaced.

Its zero degrees at the moment, so I don't fancy taking it apart tonight, but I'll check the wiring from the connector block to the fan housing and then remove the fan motor at the weekend to see if it can be repaired.

The fan however has definitely worked at full blast on a couple of occasions (I've only had the Bongo 1 week).

Oh - almost forgot - I noticed that the 30A PAL Heating fuse (17) had blown since when I last looked on Sunday.
I swapped it with a spare one and it hasn't blown after playing with the heater controls for 5 minutes or so.
Any idea why this might have blown ?

If anyone has any other suggestions, please let me know.

Cheers
Phil

[g8dhe]

The fuse only covers the fan itself so no other circuit should be involved. If you have the Ignition turned ON then the fuse is connected thru to the fan motor via the relay so if you have been playing about with the fan at any time with the ignition turned on then there is every chance it could blow whilst mucking around.

[Simon Jones]

Common problem is the drain hole in the centre of the scuttle below windscreen gets blocked so rain water overflows into the fan bearings. Remove the flat plastic 'funnel' that feeds air to the fan. With the ignition switched off, reach your hand inside the fan unit and try spinning the fan blades. It should turn quite freely and continue to spin for a second or so when you let go. If it does not spin smoothly, then your bearings need attention. The extra load of a stiff motor could be enough to blow the fuse. Be careful though: if you continue to use it with stiff bearings you stand a chance of knackering the resistor pack which has a habit of melting the solder joints when it gets overloaded.

[philscotland]

Thanks Simon

Yes the fan motor spins very easily by hand, so hopefully the bearings are ok.

I checked the drain holes at the weekend and they are clear - it's on my maintenance checks every few months now.

The main suspects now are probably the brushes or the wiring from the plug to the fan motor.

The previous owner fitted a leisure battery and what looks like a home made metal battery tray, which is very close to the wiring to the fan motor.

I'm going to dismantle everything at the weekend and hopefully get to the source of the problem.

The fact that I have heard the fan motor run a couple of times is confusing me - could this still happen if the brushes were worn - maybe it makes contact intermittently ?

Cheers
Phil

[lazyb5]

Hi Phil as you dismantle the fan the brushes are on a plate with springs behind to push onto the rotor. Mine had a seized bearing so plenty of grease and crocodile clips to keep the brushes in their home whilst you put the fan rotor back is the way to go. Don't forget one of the wife's tights over the square inlet to keep all the flies and debris away.

[Simon Jones]

Don't forget one of the wife's tights over the square inlet to keep all the flies and debris away.

Ask her to take them off first though

[philscotland]

Found the culprit of my problem !
As suspected, my metal leisure battery tray was chafing the fan heater wiring.



Rewired and all working perfectly now

Thanks for everybody's help on this matter.

[lazyb5]

Good find hope you cleaned the fan whilst it was out