ML63 Blower - RHD/LHD Question

[Steve_B]

Weird one this but would I be correct in thinking that the blower unit, the one that provides air circulation to the interior of the car, has different part numbers dependent on whether it is for a rhd or a lhd vehicle?

I brought the car with me from the UK to NZ and needed to replace a faulty blower. Given the exorbitant cost of a replacement in NZ I ordered from the US not thinking there would be a difference between left hand or right hand drive models for this part. This may be my mistake as, now it's fitted, I'm getting next to no air through the vents even when the fan is working and set on high. Although not specific to the ML, I have seen the odd case, relating to old range rovers, on a google search that the rotation of the fan spin may be opposite for rhd over lhd vehicles but the issue doesn't come up with the searches I've carried out that are specific to Mercedes.

If this is the case, is there an auto electrician in the house to advise if I can rewire the fan (polarity) to get it to run the opposite way without setting fire to the car?

 

[E55BOF]

Are the part numbers different for the fan assembly for rhd and lhd versions of your ML? If so, the one you bought from the States is the wrong part.

When the fan motor gave problems on my SLK, I found that the part numbers for the lhd and rhd blower assembly were different, but that is because the assembly is fitted above the passenger's footwell in the R171. If that's the case with your car, even if the motor wiring connections are altered to make it spin in the opposite direction it won't work very well if at all, because the actual rotor impeller is set up to pass air efficiently in only one direction.

 

[Steve_B]

Thanks for the reply

Are the part numbers different for the fan assembly for rhd and lhd versions of your ML? If so, the one you bought from the States is the wrong part.

That would be a good start to find out and the honest answer is I don't know.

However, the replacement blower I have from the States is for the same model, same year vehicle and which fits in exactly the same way (and it does fit perfectly) with the only difference being that it's for a lhd rather than a rhd car. There's a lot of things I'd expect to be different, but not a fan.

The other issue I'm having is locating a fan which states specifically for 'rhd'. There is an abundance of blowers listed but I've yet to find one that says anything other than 'lhd'.

Do you have a recommendation for a site that displays part numbers so I can check your suggestion of doing a comparison?

 

[E55BOF]

On the R171 the blower mounting duct assemblies are mirror-image different depending on which side they are fitted. The motor and fan from a lhd will physically fit into a rhd assembly, and spin up, but flow very little air. If your blower assembly is mounted centrally, there'd be no reason for the motor and fan to be different between lhd and rhd, and the cause of your problem would likely be a faulty air direction flap within the heater asssembly.

Do you still have the one you took off? Is it identical in every way to the one now fitted, particularly the vanes on the fan drum? Are there part numbers on both? Are they the same?

I don't know of a site such as you ask for, but if you post your VIN on here, I'm sure somebody who has the MB EPC will look up the correct part number for your car, and you can compare that with the part number of the blower and fan you bought.

 

[Steve_B]

Yes, I still have the old one. The fan vanes do look different, black versus white, and I assumed that this was simply an upgraded version given the age of the vehicle. In every other sense, they look identical*. The new fan operates, spins up and responds to the controls, low/high fan speed, but nothing comes through.

Taken from the original blower, the part number is shown as A1648350207. The bizarre thing is that even searching UK sites, where you'd expect all rhd parts to live, I still cannot find anything but lhd units for sale.

W164 Blowers

* note - The one I have from the States, despite being the same manufacturer (Valeo), is, on closer inspection, *different in that the vanes go in the opposite direction so this has to be the problem.

So here's what I'm thinking; I can try and remove the fan vanes from both and swap them, old vanes onto new unit (probably a risky exercise based on difficulty or tolerances/damage caused in the removal) or simply replace the removable circuitry from the new one and try it on the old one. Not knowing what caused the old one to break is a bit of a worry as if it's something physical that's gone wrong, i.e. it's seized, then it may blow the newly adapted board.

I think the board I'm referring to is noted as being the 'resistor', or part of that, and it is easy to remove from the top with just 2 screws, the same on both.

What could possibly go wrong

 

[E55BOF]

Same as the R171, then. The motor impellers are handed, and the one you've bought is no use 'as is'.

If the old motor will spin easily by hand, it's not seized. My money's on it being the regulator pack, not the motor. See this thread on the Other Side:

Ml w164 heater blower issues

Are there any signs of water ingress or corrosion?

If it's the regulator pack, swapping them over will solve the problem. However, since the replacement motor/impeller assembly is no use to you unless you can either return it, or be bothered to sell it yourself, I'd try the old pack on the new motor first.

If the motor still runs OK, you know it's definitely not the regulator and that you need to replace the old motor.

If it doesn't, then either the regulator is dead, or it's frying the motor, in which case you've fried a motor which was no use to you anyway, and you're left with one known good regulator to try with the old motor.

I think the cause of your problem is very probably the regulator, but if not, you've nothing to lose by trying to remove the impellers and swap them over.

Good luck, and let us know how you get on.

 

[Steve_B]

Ok, I tried the new regulator on the old unit and got little to no air flow at the vents. Completely baffled as all the noise was there, as in the blower sounded like it was doing what it was supposed to at varying speeds, but no flow through the vents. So I went for plan 'b'.

Installed the old impeller head into the new blower unit and it 'works', with the caveat and further observation of its performance at the bottom of this post.

For anyone attempting this in the future then the best way to remove the impeller from the unit is as follows:
Remove the clamping washer carefully from the bottom of the spindle with a small flat headed screwdriver. (Although the top looks inviting to a spanner, don't, as it's plastic and you'll just destroy it).
Equally, around the circumference of the washer, lever it gently upwards until it is free from the locking groove on the spindle. Once clear of that groove, after removing the regulator board, tap the spindle until the washer/impeller is free. You'll need that washer again when you put it back together.

No water ingress in the regulator.

The result of the swap is that I'm getting circulated air through the vents but, on limited testing, it would seem to be 'reduced' flow. It's hard to quantify, other than the ventilation was previously excellent whereas it is now just about adequate even on full fan speed. When the unit originally packed up it wasn't gradual, it started and then just stopped whilst stationery, so a blockage that could give a reduced airflow, to what I have now, can hopefully be ruled out.

I'll monitor it over the coming days and report back but I have just ordered an identical to the original and inexpensive second hand blower online from Australia so will hopefully have a backup.

If not, then I'll have to bite the bullet at MB (retail for around NZ$1,700).

 

[E55BOF]

Hells teeth, that's £900! Are there high import duties on car spares in NZ?

If I understand you correctly, the old motor stopped working, so you replaced the regulator, and it then started working again. That points to the original regulator being u/s.

However, though you then got all the noise from the old motor, you did not get any air flow, but the air flow was fine before it stopped. Replacing the regulator would not affect the air flow, so if it was blowing air before, you have a blockage or a heater unit flap problem.

You moved the impeller from the old motor to the new, and you have all the noise, but reduced flow.

I'd say the cause of the stoppage was probably a faulty regulator, though just possibly a poor connection, and you also have an intermittent fault or faults with the air control flaps in the heater unit. I'd imagine a STAR session would be able to identify any faults there.

I don't think it's a physical blockage of the pollen filter, because it was flowing air, then it wasn't, and now it is at least partially. Physical blockages don't usually cure themselves.

If you need a brand new motor, if it would achieve a worthwhile saving I'd be quite willing to get one in the UK and ship it out to you at cost.

(Incidentally, I was last in Auckland in 1954. I don't remember much about it, but I dare say it's changed a bit since then...)