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Installing a LHD Climate control fan in a RHD HVAC car

Started by WGB, 20 March 2010, 08:38 AM

WGB

Since I purchased my 6.9 (2 1/2 years ago now) I have contended with a squeak at one or other fan speed which this summer has become almost continual and has often made me leave the car at home.

Urban Myth has it that RHD HVAC fan motors are no longer available and even if they were I am not so sure they would be as affordable as the US variants are.

Thanks to trail blazing by "Goldacre" (who popped in for a visit today) this week a new US fan motor arrived from autoausaz.com and on a beautiful Perth day I started fiddling with it.

It has a few differences

1) The electrical cord is shorter and terminates in a 2 pin Bosch connector.

2) The electrical cable exits the motor at a different point

3) The fan spins in the opposite direction

4) Both motors have a system of ventilation where air enters the motor via an entry hole hidden beneath the hub of the birdcage fan but the exit spigot is about 30 degrees different between the two motors.
This exit spigot is connected to a moulded rubber tube which presumably exits the cooling air back into a lower pressure part of the ducting.

This ventilation is presumably good and bad for although it cools the motor it also fills it up with decades of crap and either the bearing or more likely the brushes and commutator start squeaking.

I had an old section  of ducting and spare old motor so I was able to test it with both an old fan motor and also the new fan motor before tearing the car apart .



Here is the old scrap ducting showing on right of picture the lever that is controlled by a bowden cable from the fan switch to open or close airflow into the HVAC system and beneath it the vacuum diaphragm worked by the temperature knob that controls the flap that mixes fresh or recirculated air.



Here is an original motor mounted showing the position of the ventilation hose and the exit point for the wiring harness.



Here is the new US motor fitted showing the differences. I had toyed with drilling new holes in the housing and moving the trapped nuts but had second thoughts as the rubber moulding will stretch and I secured it with cable ties so it wouldn't slip in the future.



Here is the new motor showing the large ventilation hole which is usually not visible beneath the birdcage fan.



Here is an old fan complete with it's original balance weights attached to the new motor.

It was not difficult to change the fan. I removed the old spring loaded central pressure clip and jammed two large screwdrivers between old motor and the fan. Putting the motor in a vise I tapped the central shaft with a small hammer and a bolt quite gently and then with keeping  the pressure on with the two screwdrivers the plastic fan crept up the motor shaft.

The fan is reasonably easy to get at but does require glove box liner, knee rolls and lower ducting removed. I removed the glovebox door as well but this is not really necessary.



Here is the old fan in position and as the wiring is a bit of a stretch it is worth cutting the old cable as close to the motor as is practical both to aid getting the motor out as well as to give enough length with the new wiring.



Here is the new motor in position with cable ties on the ventilation tube to make sure it doesn't slip and an original two pin Bosch connector taken from my parts car connecting the old with the new wiring.

The polarity at this connector has been reversed so that the red power supply is connected to the brown earth lead of the new motor and vice versa.

It has a good output and the sounds of silence are deafening.

Bill

TJ 450

Well there you go, that's a perfect fit if you ask me. ;)

That connector would also make life a lot easier in regards to removing the unit in the future, as well.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

s class

Awesome WGB.  Thanks for so clearly documenting what is involved in the project. 


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

oscar

Absolutely, great work WGB. 
I read you say it has "good output". Was there a noticeable increase or much the same but quieter? 
2.5yrs, is that all.  To me it seems you've had that car for many more.
1973 350SE, my first & fave

WGB

The output was never a problem Oscar - only the squeak.

Initially the squeak would start at one fan speed and changing the speed would clear it but recently it had become a constant companion.

I took it for a run up to Mundaring Weir Dam and it was quiet at all speeds but reminded me that I have a small rattle from the sunroof that has returned since I replaced the headlining over xmas.

I have had my 6.9 for only 2 1/2 years but I have had my 450 for nearly 7.

Bill

koan

Good work WGB and well done on getting the squirrel cage off in one piece, can be tricky, I've destroyed the odd one along the way.

Plain bearing motors are annoying when they get a bit of wear, nothing fixes them.

Shame the mounting screws and cooling hose angle relationship changed.

koan
Boogity, Boogity, Boogity, Amen!

Big_Richard

we at work have grease that's $500 per 2 gram tub that's used for lubricating phosphor bronze bushings that have chrome plated stainless steel shafts spin in them for a decade at a time between failures.

koan

Quote from: Major Tom on 21 March 2010, 03:10 AM
we at work have grease that's $500 per 2 gram tub that's used for lubricating phosphor bronze bushings that have chrome plated stainless steel shafts spin in them for a decade at a time between failures.

Nice, if M-B used it 30 years ago WGB wouldn't have had to put up with the squeak for 2 1/2 years. There again maybe it was invented "yet" ;)

koan
Boogity, Boogity, Boogity, Amen!

WGB

Quote from: Major Tom on 21 March 2010, 03:10 AM
we at work have grease that's $500 per 2 gram tub that's used for lubricating phosphor bronze bushings that have chrome plated stainless steel shafts spin in them for a decade at a time between failures.

M-B must have used an even better grease as the motor lasted for 3 decades ;D

At $250 for a new motor it's cheaper to buy a new one than service the old with that lubricant.

But seriously - I'm not sure it is the bearings that make the noise.

My guess it is the commutator and brushes that make the noise.

I never pulled my own motor down but pulled the squirrel cage off an old one that came from Nathan and the inside of that motor was packed with black dirt.
There is no filter on these systems as they have in modern M-B's so dirt filled inlet air is circulated through the fan motor to cool it - I guess some of the dust stays there.

Bill

Big_Richard

#9
its not uncommon for leaves and shit to get into the motors from the cooling duct, which by the way, flows high pressure air in from the rubber tube side which exits at the shaft side of the motor into a low pressure area. My rubber hose was full of leaves and twigs which had started entering the motor, even though the airflow to cool the motor was infact non existant, it's survived error free.

koan

Quote from: WGB on 21 March 2010, 04:12 AM
M-B must have used an even better grease as the motor lasted for 3 decades ;D

But the motor didn't actually run for 30 years.

Quick calculation, a car with 250,000 kms at an average speed of 30 kmh has only run for 347 days, assuming the fans been on all the time, not much really is it...

Might work out many engine rotations that is next.

(I realise I've over simplified things a bit!)

koan
Boogity, Boogity, Boogity, Amen!

Big_Richard

another interesting calculation one can perform based on their odometer, is how much fuel the car has burned in its lifetime, and then how much pollution its released into the atmosphere.  8)

wacotech

Quote from: WGB on 21 March 2010, 04:12 AM
Quote from: Major Tom on 21 March 2010, 03:10 AM
we at work have grease that's $500 per 2 gram tub that's used for lubricating phosphor bronze bushings that have chrome plated stainless steel shafts spin in them for a decade at a time between failures.

M-B must have used an even better grease as the motor lasted for 3 decades ;D

At $250 for a new motor it's cheaper to buy a new one than service the old with that lubricant.

But seriously - I'm not sure it is the bearings that make the noise.

My guess it is the commutator and brushes that make the noise.

I never pulled my own motor down but pulled the squirrel cage off an old one that came from Nathan and the inside of that motor was packed with black dirt.
There is no filter on these systems as they have in modern M-B's so dirt filled inlet air is circulated through the fan motor to cool it - I guess some of the dust stays there.

Bill
I took my motor apart and lubricated it well. with in afew days i could here a sqeak again, not so much, but it was there - there is no way the lube had dried or gone away in this time - could well be something else causing the sqeak -

or is this a chrome shaft, phosphor bush issue?

WGB

Don't know what causes them to squeak but looking at this posting it was nearly three years ago that I replaced the motor and it still works well with no squeak.

Bill