Another fan motor question

andyw · 13th June 2007, 11:41

I am gearing myself up to replace the aircon fan. I currently have a three speed fan on an early 53 car.

I have bought a complete two speed assembly from roverbreakers. It comes with the fan housing the fan, fan motor and control unit. I have also bought a resistor upgrade from Jules which I intend to fit before I do the upgrade.

The question is how do I go about the swap out. I have read Mikes how to which describes all the dismatling and I have also read an article from Car Mechanics which recommends cutting a slot in the fan housing so it can be liberated from the air con pipes.

I don't want to dismantle the air con pipes so i think I am left with two options.

Option one is make a cut in the new and old housing and swap the entire assemblies or

Option two swap over the individual components.

Which would you do and is there anything I'm not aware of that might influence my decision?

Thanks

Andy

crofts · 13th June 2007, 12:57

Assume the assembly wasn't new. Could I ask what they charged for it ?
Unless your housing is in considerably better condition than the bought one then I would think your option 1 is the best way to go (and doctor the housing too)
As Car Mechanics said 'can't think why Rover didn't make the housing with the cut out in the first place'.
Only remains for someone to advise best placing for the control box as I imagine you can resite to make it more accessible the next time, if necessary.
Let's know how you get on, cheers, Dave

andyw · 13th June 2007, 13:03

Dave,

The assembly is indeed new. It came in a box! The units were sourced from the supplier to MG Rover who snatched them back or more likely failed to deliver them when MG Rover imploded.

I was put on to their availability by someone else on the forum last week. They are £175 complete.

The guy has a hundred or so in stock but told me he is selling five or six a week, mostly in to the trade so his stock won't last for ever.

Andy

baxlin · 13th June 2007, 15:01

There is a how-to on the .org site which shows how to "hinge" the cowl unit enough to get at the fan motor mounting bolts which are sadistically only accessible from behind. This removes the need to cut away any of the cowling.

However, I couldn't get enough purchase on (murphy's law it was the last) fan motor fixing bolt/screw, so I had to cut away the cowl. Did mean I could remove/refit the fan on the bench though, so I reckon if I did it again, this is the way I'd do it. Doh, obviously I would on my car, as it's cut away already, but you know what I mean!

HTH

Malcolm

Keith · 13th June 2007, 15:07

If you intend to fit the entire thing I would simply cut away the plastic so that it can be fitted without disconnecting the refrigerant pipes.
If not simply use the new motor and fan and bin the new cowling as apart from being nice and clean you don't really need to change it over.

Makes sure it works etc before fitting the resistor mod

MartinW · 13th June 2007, 17:36

I used the Hinge method to do my motor swap. The only aggravation and hold-up was having to carefully use a Dremel and stone to grind away the one screw. The screws are a self tapping that cuts a thread as they're assembled into the fan motor flange - two of them undid after some penetrating oil, the third was ground away. I only found out from Keith afterwards that the screws self tap a new thread as the new motor did not have threaded holes. You should be ok, if your's is already part of an assembly. As said above the Torx screws are awkwardly located behind the cowl.

pondweed · 13th June 2007, 18:04

has jules found the answer to his swap from 3 speed to 2 speed motor? I'm hanging on and not ordering one until I hear the end of that story...!

p.s was yours 175 all in or plus vat... and plus postage...?

Fraser Mitchell · 13th June 2007, 19:19

I read this post with a bit of alarm and despondency as I have a 2.5 Club Auto on 47k, and I always leave the aircon on as it keeps the compressor in good nick, (so says my local aircon place). My previous car, a Mazda Xedos 9, had two motors, Air-con, and cooling, and both never failed in the time I had the car, and I took it from 37k to 128k.

So it seems I have to 'bite the bullet' for these costly parts, and also, it seems for the VIS, at some point in the future.

What is really needed is a reliable replacement motor. I wonder what Nanjing Motor, and SAIC are using.

Jules · 13th June 2007, 20:34

Quote:

Originally Posted by pondweed

has jules found the answer to his swap from 3 speed to 2 speed motor? I'm hanging on and not ordering one until I hear the end of that story...!

p.s was yours 175 all in or plus vat... and plus postage...?

YES GO AHEAD!! and order 2 speed PW. I was barking up the wrong tree and was testing out the new fan motor without the blades fitted!

So there was no load on the motor and hence no volts drop across resistor!(well 0.5 volts instead of 7 volts on Half speed)

Sorry to mislead you all, I was going to make a 70 mile treck to Kieth's to check it out on T4, but found a mobile VehicleTech right on my doorstep!!
He has a Laptop with a small interface OBD 11/SAE J1850 16 pin for rovers.

He uses "Multi Diag" by Actia system and it replicated most of the T4 testbook functions ie:

Tested my CDT ECU which in turn sent commands to the new 2 speed fan and HEY PRESTO switched between the 2 speeds on demand !

The only mystery to me is how the ECU now knows I have a 2 speed fan instead of the old 3? Keith will know I'm sure
I will edit the original Interchangeability thread so as not to confuse any more people.

Like they say a little bit a knowledge is dangerous!

Keith · 13th June 2007, 21:01

Quote:

Originally Posted by julesbass

The only mystery to me is how the ECU now knows I have a 2 speed fan instead of the old 3? Keith will know I'm sure

It does not, it turns on the low speed relay for AC and it is the low speed relay that the resistor is wired to.
When the ECU requests medium speed it also turns on the medium speed relay as well as the low speed relay remaining on but in this case nothing will happen obviously.
So then the ecu just waits for conditions to get to the point where it then needs to request high speed, nothing intelligent is going on

13th June 2007, 11:41	#1
andyw Avid contributor MG ZT CDTi (departed to pastures new) MGTF, MGC, Join Date: Dec 2006 Location: Altrincham, Cheshire Posts: 214 Thanks: 0 Thanked 0 Times in 0 Posts	Another fan motor question I am gearing myself up to replace the aircon fan. I currently have a three speed fan on an early 53 car. I have bought a complete two speed assembly from roverbreakers. It comes with the fan housing the fan, fan motor and control unit. I have also bought a resistor upgrade from Jules which I intend to fit before I do the upgrade. The question is how do I go about the swap out. I have read Mikes how to which describes all the dismatling and I have also read an article from Car Mechanics which recommends cutting a slot in the fan housing so it can be liberated from the air con pipes. I don't want to dismantle the air con pipes so i think I am left with two options. Option one is make a cut in the new and old housing and swap the entire assemblies or Option two swap over the individual components. Which would you do and is there anything I'm not aware of that might influence my decision? Thanks Andy

13th June 2007, 12:57	#2
crofts I really should get out more....... 2003 Rover 75 Conn. SE Auto Tourer 131 ps CDTi Join Date: Nov 2006 Location: Bristol Posts: 2,512 Thanks: 38 Thanked 67 Times in 55 Posts	Fan Assembly Assume the assembly wasn't new. Could I ask what they charged for it ? Unless your housing is in considerably better condition than the bought one then I would think your option 1 is the best way to go (and doctor the housing too) As Car Mechanics said 'can't think why Rover didn't make the housing with the cut out in the first place'. Only remains for someone to advise best placing for the control box as I imagine you can resite to make it more accessible the next time, if necessary. Let's know how you get on, cheers, Dave __________________ Rover 75 CDTi SE Connoisseur Tourer (2003) In desirable STARLIGHT SILVER (now restored to it's former glory with all the chrome !)

13th June 2007, 13:03	#3
andyw Avid contributor MG ZT CDTi (departed to pastures new) MGTF, MGC, Join Date: Dec 2006 Location: Altrincham, Cheshire Posts: 214 Thanks: 0 Thanked 0 Times in 0 Posts	Dave, The assembly is indeed new. It came in a box! The units were sourced from the supplier to MG Rover who snatched them back or more likely failed to deliver them when MG Rover imploded. I was put on to their availability by someone else on the forum last week. They are £175 complete. The guy has a hundred or so in stock but told me he is selling five or six a week, mostly in to the trade so his stock won't last for ever. Andy

13th June 2007, 15:01	#4
baxlin This is my second home Volvo C70 Convertible and JZR 3 wheeler Join Date: Nov 2006 Location: Tring, Herts Posts: 3,960 Thanks: 124 Thanked 173 Times in 124 Posts	There is a how-to on the .org site which shows how to "hinge" the cowl unit enough to get at the fan motor mounting bolts which are sadistically only accessible from behind. This removes the need to cut away any of the cowling. However, I couldn't get enough purchase on (murphy's law it was the last) fan motor fixing bolt/screw, so I had to cut away the cowl. Did mean I could remove/refit the fan on the bench though, so I reckon if I did it again, this is the way I'd do it. Doh, obviously I would on my car, as it's cut away already, but you know what I mean! HTH Malcolm

13th June 2007, 15:07	#5
Keith This is my second home ZT400 Join Date: Oct 2006 Location: Ellesmere Posts: 5,948 Thanks: 0 Thanked 43 Times in 29 Posts	If you intend to fit the entire thing I would simply cut away the plastic so that it can be fitted without disconnecting the refrigerant pipes. If not simply use the new motor and fan and bin the new cowling as apart from being nice and clean you don't really need to change it over. Makes sure it works etc before fitting the resistor mod

13th June 2007, 17:36	#6
MartinW Newbie MG TF LE500 Join Date: Nov 2006 Location: Chester Posts: 2 Thanks: 0 Thanked 2 Times in 2 Posts	I used the Hinge method to do my motor swap. The only aggravation and hold-up was having to carefully use a Dremel and stone to grind away the one screw. The screws are a self tapping that cuts a thread as they're assembled into the fan motor flange - two of them undid after some penetrating oil, the third was ground away. I only found out from Keith afterwards that the screws self tap a new thread as the new motor did not have threaded holes. You should be ok, if your's is already part of an assembly. As said above the Torx screws are awkwardly located behind the cowl.

13th June 2007, 18:04	#7
pondweed This is my second home Waiter, Waiter! I seem to have a Roomster in my drive... Join Date: Nov 2006 Location: Sussex Posts: 3,268 Thanks: 0 Thanked 1 Time in 1 Post	has jules found the answer to his swap from 3 speed to 2 speed motor? I'm hanging on and not ordering one until I hear the end of that story...! p.s was yours 175 all in or plus vat... and plus postage...?

13th June 2007, 19:19	#8
Fraser Mitchell Gets stuck in Rover 75 2.5 V6 Club Auto Join Date: Feb 2007 Location: Crewe Posts: 898 Thanks: 0 Thanked 0 Times in 0 Posts	I read this post with a bit of alarm and despondency as I have a 2.5 Club Auto on 47k, and I always leave the aircon on as it keeps the compressor in good nick, (so says my local aircon place). My previous car, a Mazda Xedos 9, had two motors, Air-con, and cooling, and both never failed in the time I had the car, and I took it from 37k to 128k. So it seems I have to 'bite the bullet' for these costly parts, and also, it seems for the VIS, at some point in the future. What is really needed is a reliable replacement motor. I wonder what Nanjing Motor, and SAIC are using.