[xj] upgrading squirrel cage ventilation fans S1 XJ6?

XJ
21

In reply to a message from awg sent Fri 5 Feb 2016:

If you search ‘‘universal 12V heater fan motor’’

there are many cheap items available.

seems most modern cars have one fan, but they move a huge
amount of air…and draw a lot of current

If I replace the DRIVER side motor only, that may give me
the desired result, the original cage wheel grafted on.

If it spins TOO fast, current limiting can be employed–
The original message included these comments:

The GM Commodore fan (motor) I am hoping to fit pulls up to
280W… which indicates over 22A!..that is ~3 times what
the 420G motor pull max, fitting 2 would be big.

–
Tony
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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22

In reply to a message from awg sent Sat 6 Feb 2016:

Hi Roger, and other S1 owners

Although it will take a few more hours work to get
everything installed, it does seem 99% that a GM VT
Commodore fan MOTOR, is an almost direct transplant for the
MKX/420G/S1 XJ etc fan motor.

I obtained a complete unit with speed controller for $40
The speed control is not wired

It is rated at 300 Watt, and the airspeed is simply awesome
compared to the Jag units, which draw ~60 Watts by my calcs.

Dimensions are within mm, and 2 of 3 mounting legs even line
right up

The shaft OD is 7mm, compared to 6.4mm for the 420G.

The original squirrel metal cage must be retained, as fit is
close, the plastic Commodore one is too big

I intend to turn the shaft down by spinning the motor while
applying files and emery paper, as the 420G squirrel cage
mounting system is very well engineered.

I have to make sure everything is very well made, the fan
spins so fast, any miscalculation would not be good.

In addition, this fan will spin either CW ( as indicated) or
CCW if polarity is reversed.

My Mrs daily driver is a later model of this car, and the
fan on full nearly tears your face off, I set it that way on
very hot days, only one is in most modern cars apparently

GM VT Commodore would be one of the most commonly wrecked
vehicle in Australia–
The original message included these comments:

If I replace the DRIVER side motor only, that may give me
the desired result, the original cage wheel grafted on.
If it spins TOO fast, current limiting can be employed

–
Tony
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –

===================================================
The archives and FAQ will answer many queries on the XJ series…
FAQs: http://www.jag-lovers.org/xjlovers/xjfaq/index.html
Archives: Jag-lovers Forums - Jag-lovers

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24

Hello Tony. I’m new to posting, but a long-time reader of this forum. Excellent older thread here. Thanks to each of the thoughtful contributors.

I have a Series 1 XJ6 and want to upgrade the cage fans. I’m inclined to follow your advice from this thread. What model years of the VT Commodore should I be looking at for the motors? Since you installed the motors back in 2016, do you want to add any updates or additional recommendations based on your experiences ? Thanks in advance.

25

Sorry I cant give you any updates, my vehicle is a 420G and the fan moves a lot more air

The only real advice I can give is to remove your XJ fan and take it to the wreckers

Commodores have specialist wreckers and I think mine was “off the shelf” and cheap

I think I changed the squirell cage fan unit from the 420G to the GM shaft to fit the housing, as clearance is very tight

No idea what year VT it was, but it was well worth doing, fan unit cost about $20.

I would be inclined to fit a continuosly variable PCM controller when my project is complete…that way you have complete control over fan speed

26

Many thanks, Tony. I’ll give it a whirl. Just to confirm, we’re talking about the '97-2000 VT Commodore sedan?

27

To the best of my memory, yes VT sedans, although I think they just handed me one off the shelf, the notes above should detail what I did, but as I said, take your XJ one with you. I am pretty sure I did not use the Commodore squirrel cage, I think its too big.

I had the advantage of having some spares if I buggered up

28

E- type fans are only for heat or fresh air. The under dash A/C units fitted to the E-types are self contained have their own blower motors and fans.

29

I have a S1 XJ6, perhaps you know already that the fans are “handed”, for left and right hand side. They have different part number and turn counter to each other. I have the original fans and they work well enough with the heater for me. I have had to repair my damper actuator (with a flexible glue Stormsure) as it was limiting the swing on the damper and hence the passage of outside air. FWIW, Paul.
PS: welcome by the way!

30

Yes, I attempted to integrate the air duct fans to a front A/C system, which needed more air movement.

In any case, the original XJ fans were very anemic, and scarcley sufficient for their intended purpose, they also develop a squeeky bearing, The VT Commodore items are like a tornado on maximum setting

I am almost certain the Commodore fans just need a change in polarity to change direction of rotation

31

These early S1 fans are series-wound (field coils and armature coils wired in series) “universal” or “AC/DC” motors. Because the field and armature electromagnets continue to attract one another when the magnetic polarity of both changes at the same time, the motor’s rotation direction is determined by internal wiring and is independent of input polarity (even if polarity reverses 50-60 times per second.)

However, later in S1 production the motors were updated to permanent magnet fields. Because the field’s magnetic polarization doesn’t reverse but the armature’s magnetic polarity does, these motors reverse when input polarity is reversed. This feature is exploited by having a pair of spade input for +12V and ground (isolated from the motor frame). The polarity is reversed between the left and right motors to provide appropriate rotation direction. And there is only one part number.

As Paul suggests, you need both motors to rotate in the correct direction for their centrifugal fans to pump air. The first (series wound) fans can be messed up by reversing the physical location of the motors. The second (permanent magnet) can be messed up by incorrectly wiring one or both of the fan motors. IMHO.

1 Like
32

Seems to me your HO is very sound, Rob. Paul.

33

Helpful info, everyone. Thanks