Front heater fan only working on 4

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bongobaz
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Front heater fan only working on 4

Post by bongobaz » Mon Oct 02, 2017 11:17 am

As above,
Tried heater and fans only come on at level 4 its a 95 diesel manual heater.
Hope its a simple fix.
Any advice much appreciated.
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Re: Front heater fan only working on 4

Post by g8dhe » Mon Oct 02, 2017 11:22 am

Sounds like the resistor pack under the bonnet has popped some of the thermal fuses in that case.
Image
just need to solder down the tabs that have released to fix them again, but you might also need to clean out the fan motor which is often the cause of them popping out in the first place.
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Re: Front heater fan only working on 4

Post by bongobaz » Mon Oct 02, 2017 11:34 am

Thanks Geoff that's a start, where is said pack and how do i clean out motor?
Knew you would be on the case. =D>
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Re: Front heater fan only working on 4

Post by mikeonb4c » Mon Oct 02, 2017 11:51 am

bongobaz wrote: Mon Oct 02, 2017 11:34 am Thanks Geoff that's a start, where is said pack and how do i clean out motor?
New you would be on the case. =D>
Under the bonnet Baz. Can't remember where its so long since i did mine but a search on here (or factsheets) should reveal if Dr Geoff isn't back shortly. Don't forget that something underlying probably caused it. Usual culprit is stiff motor bearings from rusting due to water dropping on them as a result of rainwater overtopping a chronically blocked windscreen channel drain. Motor not that hard to remove (you can test fanblades for stiff turning with it in place but i THINK it needs removing for wd40/oiling
though can't remember tbh). Hope you get it sorted ok.
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Re: Front heater fan only working on 4

Post by g8dhe » Mon Oct 02, 2017 3:11 pm

Ok clean out the window screen drain hole first as its normally this which causes excess water overflow.
Then follow Ady's disassembly of the fan motor housing here
Image

Then its locate the resistor pack where the meter probes are inserted under the lozenge shaped cover that clips over the resistor pack, then unscrew it and check the state, when soldering the tabs back its best to not use any extra solder if possible (not always possible;
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Re: Front heater fan only working on 4

Post by Bob » Mon Oct 02, 2017 3:59 pm

Great info, thanks all. =D>
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Re: Front heater fan only working on 4

Post by bongobaz » Mon Oct 02, 2017 4:36 pm

Great replies,
cleaning out the drain hole has been my speciality for years. The rest looks a bit daunting. :?
had hand in the housing and fan seems quite free.
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Re: Front heater fan only working on 4

Post by mikeonb4c » Mon Oct 02, 2017 7:52 pm

Interesting Baz as i seem to recall my resistor desoldering even though my fan was not especially stiff. Mind you the heater matrix through which air must flow was badly crudded up until i cleaned it all up. Maybe mend the resistor and do a strip down and overhaul then see if all behaves after (like mine did) [-o<

P.S. Of course the first thing is to ascertain whether the problem IS the resistor desoldering!

P.P.S. its not as daunting as it looks - the only bit i recall baffling me very slightly was reassembling the spring for the recirculator shutter - these days i'd take a pic on my phone before removing it but in those days i didn't have a smartphone! :lol:
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Re: Front heater fan only working on 4

Post by Ian » Mon Oct 02, 2017 9:23 pm

Baz, shall I bring a resistor to Hope at the weekend (Ade will be there!)?
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Re: Front heater fan only working on 4

Post by Northern Bongolow » Tue Oct 03, 2017 12:43 am

2 min job bud. 8)
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Re: Front heater fan only working on 4

Post by bongobaz » Tue Oct 03, 2017 10:43 am

Not going in my bongo but thanks for the offer.
If its easy job you can run me through it.
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Re: Front heater fan only working on 4

Post by Northern Bongolow » Tue Oct 03, 2017 2:26 pm

if you look at geoffs pic above with the multimeter.

just behind the fuse box next to the starter batt is a black plastic odd shaped and angled cover that is not shown in geoffs pic, the squeeze clip to remove it is at the front of it, push the clip inwards/towards the rear and lift the cover. it has 2 clips at the rear that acts as a hinge so lift the front of the cover then you will see what is in geoffs pic. remove the wiring harness on the top then remove the 2 screws with a dumpy screwdriver then lift it out, it only goes in one way so take a good look before you remove it. you will see the legs that have desoldered themselves because of the larger amps being drawn as the front fan is stiff. you can resolder them on yours baz but really the front fan needs taking out first and inspected/lubricated as in geoffs top rusty pics.
the fan inspection/removal takes an hour to strip and clean and lube if you dont do this the resister may blow again.
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Re: Front heater fan only working on 4

Post by bongobaz » Tue Oct 03, 2017 3:15 pm

Thanks mate took resistor out today didn't really know what i was looking to solder.
It says do not repair on it.
Seems strange it works on setting 4 but not others.
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Re: Front heater fan only working on 4

Post by Ian » Tue Oct 03, 2017 3:21 pm

This is from the "Fan Resistor" factsheet:

This section describes a very inexpensive repair for the fan speed control used on climate control versions of the air conditioning. If successful, it will save over £70 on a total replacement.

First ensure that the ignition is off, and/or disconnect the battery.

The repair assumes that the fan will only work on setting 4 (maximum speed), if there is no output from the fan, then first check the fan or its associated brushes. The fan control unit has a transistor/chip built into the internals. The chip is in bonded to the large finned aluminium heat sink using heat sink paste. This looks like and is as soft as toothpaste. Replacing the chip is easy, though fiddly. It is only necessary to remove the outer plastic cover, and de-solder the three pins that project through the printed circuit board. It is usually possible to gently lever the pc board to one side. This exposes the three pins internally, which can now be cut, and de-soldered with ease.

Once this has been done, the whole printed circuit board can be lifted away, exposing the chip. The chip is held in place by one screw. Replacement is the reverse procedure, ensuring that the metal side of the chip is coated with heat sink paste (this should be available from your local computer repair shop), prior to insertion into the aluminium housing. Refit the printed circuit board and re-solder the three pins, removing the excess end of the pins on completion.

A replacement transistor costs £6.50 including post and packing from:

Nikko Electronics, 358 Kingston Road, Ewell, Surrey KT19 0DT
Tel 020-8393-7774
Website: www.dalbani.co.uk
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Re: Front heater fan only working on 4

Post by bongobaz » Tue Oct 03, 2017 3:30 pm

Cheers Ian,
Sounds like a right faf.
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