Where is the relay for the blower motor?

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Rob_e (UK)
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Where is the relay for the blower motor?

Post by Rob_e (UK) »

The other day I got in my BX to find the interior fan did not seem to work, I later realised that it was coming on but only slowly, basically it comes on when moving the control clockwise the fan gets a bit faster until it gets to the, at which point instead of switching to full speed it switches off completely. Looking at the circuit diagram in the haynes manual I am assuming that this means there is a problem with the relay used to get full speed. According to the Haynes manual the realy is located "on RH side of steering bracket". I had a load of the trim off from around the sterring coloum today but could not see any sign of the relay. Can anyone tell me where this relay is? the diagram in haynes looks like it is referring to a left hand drive version, is it somewhere different on RH drive versions?

Not sure if it makes any difference, but just in case, it is an 89 GTi 8v.

Thanks in advance
Rob
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Post by jeremy »

Have you modified the circuit board? Has the relay ever worked?

Read:

http://www.bxclub.co.uk/forum/viewtopic.php?t=5515
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Post by ellevie »

Welcome to the forum Rob.

The 1983-89 Petrol Haynes manual page 363 states,

"the fan control module on later models is located on the fan motor casing within the scuttle plenum chamber instead of being mounted on the steering column support bracket"

There are also differences in the wiring arrangements as shown on pages 410 and 427.
David

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Rob_e (UK)
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Post by Rob_e (UK) »

Jeremy,
I saw that post the other day, is this something that only affected some models. I have never modied mine but it did used to use the relay and acheived a pretty high fan speed; I can't be sure if it was the full motor speed or not, but it was a big jump in speeed when you moved the dial the last little bit. It did work previously, you used to be able to hear a click from a relay when it went to high speed; I just wish I had taken more notice of where the click came from now :lol:

ellevie,
I think I might have a different manual as p363 is about coolant pumps and carburettors. The cover of mine says 83 - 94, it is the Owners Workshop manual, is yours the service and repair one?

I have replaced the whole fan motor assembly years ago and I think mine did have the control module on the fan housing, but I don't remember seeing the relay there, is the relay attached to teh fan housing as well?

Thanks
Rob
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Post by ellevie »

On my 19TRS the relay is just above the top right hand corner of the pedal box. You don't need to remove the steering wheel shroud to see it.

I think the mod only applies to some models as my manual 19TRS which I have had since 1992 operates the relay correctly and I have certainly never done a mod on it.

My Haynes is the Owners Workshop Manual (number 908) but there isn't really any more information than I've given you. Just be aware if you need to fault find the circuit that there might be variations.
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Post by jeremy »

My 'Best' Haynes - brown cover 83-94 with all the supplements has the reference on p361 under the heading 'Fan control module for air conditioning - from January 1987.' (The later Blue covered edition is edited highlights and not as good)

From the sound of it your car didn't need the modification or had already been done. I did the mod to my car (sept 1989) but never bothered to find the relay as I could hear it working somewhere around the steering column.

I did have enormous trouble getting the connections to the heater fan to work at all as they were heavily corroded and whatever I did wouldn't shift it. Indeed I was about to cut the connectors off and replace them with something else when the thing came to life so I left it all alone and its been OK for another 3 years. This was at the time I did the modification as I couldn't clear frost off the screen.
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Post by ellevie »

The fan on my K reg 19TXD which I acquired earlier this year didn't work because the previous owners had broken the panel and hacked the pcb in an attempt to fix some fault and the rotor was completely missing from the pcb. I have now installed a domestic light switch between pins 2 and 4 which activates the relay under the steering column. The switch also conveniently fills the broken gap in the panel and at least now the fan works on full power for defrosting/demisting with the winter coming on. It's surprising how much heat is thrown out without the fan just by convection when the heater is fully warmed up, so I should be ok with just these two options.
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Post by Jaba »

Rob

I would be inclined to start at the beginning. If you have a voltage meter first make sure you have a steadily increasing voltage across the fan motor with its leads removed while you move the control to max.
If you have then it is the motor that wont do full speed.
Where next ? Well I would plug in a known good motor with its power regulator board to see if that will spin at full wack. If it wont you could have an issue with the carbon track behind the rotary control. Also its slider pickup is a flimsy affair that can become a bit loose.


It is likely you wont measure a good voltage at full speed. Then, if you havent, you need to next establish if your pcb has been reworked or not. As per Jeremy's post.
Most BXs do NOT have the circuit shown in Haynes i.e. the high speed relay down by the pedals is never actually in the circuit. This is even on aircon cars.


The usual culprits are corrosion of terminals, the motor brushes, the power regulator transistor or the actual rotary control mechanics or electrical connections. Just follow the appopriate circuit to find the problem.
Plenty to keep you busy.
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Post by Rob_e (UK) »

I have found that note in my manual now, in mine it is also on page 361. I didn't realise they printed more than one version of the Workshop manual, I thought it was just that one or the new dumbed down service and repair versions.

Any way I have had a look and the relay on mine is above the pedal box as ellevie suggested it was. Looks like I removed all the steering shroud yesterday for nothing :)

I think I must have one of the later versions of the heater control as it didn't look like anything had been soldered on to it when I changed a bulb a while ago, but there has always been a significant increase in speed when the dial was turned the last few degrees; and I am sure there used to be a click from the relay, until the point where I lost full speed.

I haven't tried measuring the voltage at the fan, but if I put my hand in front of the vent I can feel a steady increase in the amount of air coming out, then it stops when you turn the dial the last few degrees. I haven't had a chance to check the relay yet, but I will probably try that first , now I know where it is.
I had a look on maplins website and it looks like a replacement is only about £2, I am assuming the pin configurations for relays are pretty standard.

Thanks for all your help, I will let you know how I get on once I get a chance to look a tthe relay.

Rob
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Post by ellevie »

There is a good chance that the problem is due to poor contact at one of the connectors or even the control rotor. Why not clean the various connectors by applying some WD40 and pushing them on and off a few times, including the pcb connector and the relay connector. Also give the rotor contact a squirt and a wiggle to clean it.

If you have a multimeter you should be able to measure about 12V on pin 4 on the pcb (counting from the right). If the voltage is present then grounding this pin should operate the relay and you should hear it click.
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Post by jeremy »

You could check the relay by swapping it for another of the same type from elsewhere on the car.
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Post by mnde »

Dare I utter the words "rubber mallet" and "blower motor" together in this thread..... :o :wink:

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Post by Stinkwheel »

Dare I utter the words "rubber mallet" and "blower motor" together in this thread.....

go for it Mark :)

Always my first port of call when something wont work...............big mallet, works with everything, cars, bikes, kids etc :twisted:
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Post by Way2go »

mmmh.........Rubber Mallet :? the car equivalent of using a defibrillator on a human patient! :wink:
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Post by Stinkwheel »

mmmh.........Rubber Mallet the car equivalent of using a defibrillator on a human patient!
Neither did my misses any good, she still pegged it. :(
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To slightly mis-quote Kitch ... "BX 14. They're just brilliant!"
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