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MG MGF Technical - Blower Motor (Speed 1)

On the way in to work this morning I noticed in MKI MGF (95) that speed 1 on my blower (the speed I leave on as default) is not working. The switch feels perfect. My guess is the fact that some debris such as leaves has fallen in the system and possibly fouled the motor (I have had leaf type noises coming from it sometimes in the past). If somethinmg has fouled the motor, it would stop (especially on low speed or ramp up speed) and draw a very high current that could potentially burn out any resistors that are there in the speed switch. Has anyone had this problem, or indeed does anyone know where the resistors are located, behind the switch or at the motor. What are the values and rating of these resistors, if indeed they have burnt out.

I'll be checking ny circuit diagrams tonight, but am concerned that they do not go down to this level and that they just label a box called "motor".
Martin

Martin

Like you I leave #1 on as default on my March 96 *F* and like you my #1 blower no longer works - #2 upwards are fine - so I have put it down to the switch resistors. If you find out how to repair it please let me know.

Ted
Ted Newman

Same thing has happened to mine but ony 3 or 4 blow any air, again I had the same leaf in vent type noise.

I would love to know how to fix this

Ralph
Ralph

I've had total failure of the heater fan- that was due to a short in the multi-connector. When the fan worked, the night illumination lights would be on for the panel- and extinguished when the head lamps were switched on. All fixed when I cut the plug out and replaced it with a high current capacity chocolate block connector.

It doesn't sound much like the fault that you chaps report though, sorry.

Rob
Rob Bell

I think the F uses heater system parts from Rover 200.
The most likely cause of this fault is a faulty resistor pack in the heater motor case. Access can be gained by removing the glovebox & the resistor pack is held in by 2 screws. You should be able to see on removal if the resistor coils are burnt out or not
once it is removed. They sre not expensive to buy if
a replacement is needed.

Rob
Robin Streeter

Part number JGM100060 if your interested.

Rog
Roger Parker

>Part number JGM100060 if your interested.

;-)
me in any way.
Can't recall the disassemly from the wreck. Got the switchboard, but the heater and wiring is still in the wreck.
May be I find time to take a photo on Friday.

Cheers
Dieter
Dieter Koennecke

Nice to know some things never change.....My maestro heater only works on 3-on the last 2 cars. Personally, I'm looking for a variable resistor as in peugeout's to replace the switch.
karl


Hi all,

my old (t)rusty winter car , SAAB 900 had the same problem a few years ago. First the slow speed went , than next one and finally stuck with full force or nothing att all !! This was of course due to the rather hefty resistors needed for speed adjustment broke / blew up with time. Solved that last winter by making a PCB with a PWM,(pulse width controller ).
A small printed board and a power-fet regulates any DC-motor up to the current limit of the fet, in this case 30 Amp. This done with almost no generated heat in the circuit. Original regulator switch was replaced with 100kohm potentiometer = continuos speed regulation.
So far no problems except I added a current limiter in the circuit to be safe if motor got stuck by leaves etc.

Regards , Carl.
Carl

Had exactly the same problem Martin which was resolved very quickly by fitting a new resister as Ted suggests. As for how, sorry don't know as I took the car to the dealer (she was under warranty). Total cost about 20 quid as I remember. 15p for the resister and 19.85 for 0.05 hours labour. ;-)
Cheers
Si
Simon

It pains me to read this, it's almost 2001 and they're still using Reostat's and Wound Resistors to control parts of an automobile at one end, when, at the other we've got microprocessor controlled ECU's. How cheap would it be to control an electric motor via a Potentiometer and switch mode power supply???... Pennies, with today's technology. And here we are talking about how to change a resistor (pack) Doh.

Nick ;-)
Nick

FIXED IT! - Having taken out the glove compartment for easy access. I then removed the resistor block from the side of the heater module (just above the motor). To my surprise they were not power resisitors fitted to any heat sinks, but coils of resistor wire that are designed to sit in the cold air intake flow of the heater (so they are cooled). This is very old fashioned and of course not at all energy efficient. Also, I removed the right angled air duct that takes the incoming air from in front of the screen down in to the heater module. I could then see with a torch indeed there was leaf in the blower mechanism. Not big enough to stall the motor, but enough to make an annoying flutter noise. I am surprised there is no grid on the input to stop leaves entering. I have seen this on MGB's so it's not a new idea. Moving back to the resistor module, the first resistor (resistance wire coil) was blown. The other two were a little caked with white crap, like an old fashioned electric fire that has been used a lot, so I just cleaned them up a bit so as to get a better air flow round the wire. Having done a few tests, I found that a piece of resistance wire coiled up for about a value of 1.5 Ohms was adequate to repalce this burnt out one. (There are 3 resistors all in series. All of them in series equals speed 1). The resistor block needs to be fitted back in the air flow for any prolonged action as it would just glow and burn out if there is no air flow over it. Perhaps this could be a problem if your air intake is covered with snow. Anyway, so far so good. I like the idea from Carl, but all good ideas come from Sweden nowadays, that's why I work for Ericsson and my wife has a Volvo.
See ya
Martin

Martin,

congratulations :)
I'm a bit late, but may be it helps to improve the existing resistor thing or helps to understand what you briefly described above.
I followed your instructions and took photos from my wreck parts in the garage.
Put it on that webside.
http://www.lame-delegation.de/mgf-net.de/heater/heater.htm

May I use your perfect descriptio/message for the resistor package picture row ? :)
Did it already, but would like to know your permission.

Rgds
Dieter
PS. the search engine on http://www.mgf-net.de will need some days to index the 'heater' subject.
Dieter Koennecke

No Probs Dieter. - And my DIY fix continues to work. I'm going to look at a PWM control now because I'm not too happy with this old technology of using resistance wire in the cold air flow to limit the motor speed. This goes back to the days or positive earths and point contacts in fuel pumps and voltage control boxes.

//
Martin
Martin

I can see Martin is a youngster - my early vehicles had magnetos and acetylene gas lights:)

Ted
Ted Newman

Gas light! I used have a chap walking in front with a flag.
JFK

AA Sir!
Cpl Kite

You ask any of the Nordic counties what they think of Mr Lucas.
Martin

>Gas light! I used have a chap walking in front with a flag.

Calling for Rob !!
:)
Rob,
any cartoon artist idea on JFK and his chap and the flag ?
;-)
Suppose that Ted can still carry such a flag, does he ? :)
(Would fit to the piccy of the 'front bonnet EPAS fuse pull job'.)
http://ourworld.compuserve.com/homepages/robmidgleybell/cartoon.htm



Dieter Koennecke

Okay Carl and Martin, you've got my attention. Your suggested change seems like a worthy modification.
What do I need to make one of these PWM controllers; are there suitable printed cicuit boards commercially available ? Where do I start. . .

Thanks guys

Rob
Rob speare

Dieter

Back in the dawn of motoring in the UK the landed gentry decided that these 'new fangled horseless carriages' were dangerous and so a law was passed that stated every 'Horseless Carriage had to be proceded by a person carrying a flag to warn of the approach of this motorised monster'

Hence our jesting on this matter.

BTW this is a fact and not a Teddyism!

Ted
Ted Newman

>>any cartoon artist idea on JFK and his chap and the flag ?<<

That guy would have to run really rather quickly to stay ahead of an MGF eh Dieter? ;oD

In the 'good old days' the AA used to warn motorists of Police speed traps. Can't see them doing that today- although I am sure that it would be popular with many members!

Rob
Rob Bell

For those wishing to upgrade to modern technology, you could try using module WC76H from Maplin for 13.99 incl VAT, which is a PWM module from 4 to 12V rated at 3A. The current rating could be too small. Has anyone measured what the motor takes across the range. Anyway, it's a start. In the meantime I'll stick to OEM methods old fashioned methods which is still better than my 1957 MGA having the optional accessory heater and only two settings (on or off). The web site for Maplins is www.maplin.co.uk where you may find more PWM contollers (like your kids modern train set controller maybe)
Martin


Hi all,
have been away during the week with no internet acsess so a bit late with the input ; reading Martins early thread the assembly where a fan blows thru electrically heated wires = true hairdressers car!
On the second thread , - the current demand for the heater engine at full speed is around 12 A . Any small PWM-circuit will work if the final "pass" transistor is changed for one that can handle around 20 - 30 A safely. The cost increase in doing so is only modest.

regards , Carl.
Carl

When it comes to electrical stuff my brain clouds over and I start thinking about something else. If any of you can put it in a box and tell me which wires to attach where I can handle it, anything else, la la la, I'm not listeninig, la la la la.
Tony Smith

This thread was discussed between 30/11/2000 and 09/12/2000

MG MGF Technical index

This thread is from the archive. The Live MG MGF Technical BBS is active now.