1990 Sovereign (XJ6) heater fans stopped working

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Oldbie - 20 Nov 2004 21:03 GMT

Hi,

Some time ago my heater fans stopped working. They do not come on at
all on manual or auto.

I can hear some faint electrical noise like they are trying to start
several times, then nothing.

I recently had a transmission failure light come on, and found some
dampness on the driver's floor around the connector for the kickdown
switch under the gas pedal. When I dried this out the tx fault went
away.

I spotted a water drain tube above this switch and when I disconnected
it a lot of water poured out into the drivers floor. I cleared the
drain and then noticed a bit of moisture at the bottom of the plastic
enclosures for the heater air ducts. The driver's side one had a bit
of duct tape over a drain hole and when I pulled it off I got another
half liter of water out.

The passenger's side had no taped hole that I could find, and the
water on that side was leaking slowly down onto the elctricals that
abound in that location. I drilled a small hole in the ducting and
drained another cup or 2 of water from that side.

I had previously unplugged the gas filler area drain tube jus before
it overflowed into the tank and also removed the failed electric radio
antenna and drained half a liter from that when a blob of grease had
plugged that drain tube.

Does Jaguar not realize some people drive their cars in the rain?

Anyway, I would like to get the fans working again and do not know
where to start to troubleshoot the electricals.

Can someone tell me where there might be a relay that could possibly
be checked for failure, or how/where I could actually bypass all the
heater/computer controls and attach a 12 volt power source directly to
the fan motors to see what parts I will have to replace?

- Tom

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webserve - 20 Nov 2004 22:42 GMT

Tom,
I don't think you are going to like this.

The first thing you need to check is the duckbill. When you describe your
car you need to restrain from describing things as passenger or driver. When
my son drives his Jag he sits on the left side of his car. When I drive my
Jag, I sit on the right side of my car. It is much easier for the rest of
us if you refer to left or right.

The duckbill on these cars has a tendency to fill with sludge. It is
located on the left side of the car under the wiper motor. It is a small
rubber tube that is round on the upper part and tapers to a flat opening --
thus the duckbill name. You need to find it, remove it and clean it. When
it gets clogged, it has a tendency to back up water into the heater blower
system.

Once you have done that, you need to find and clear the two drainage tubes
on either side of the transmission tunnel. These run directly from the duct
system along the transmission tunnel and outside the car. These get plugged
as well over time.

Once these are cleared, you have one more source of water -- the blowers
themselves. Chances are, these are or were full of water. Located inside the
blowers are two relays. From the sounds of things, yours have been under
water. The thing you need to do is pull the passenger's side blower. In
this case, it could be left or right depending. Once you pull the blower box
and open it up you need to clean and lubricate the motor. You can, at this
point, easily check to see if the blower motor is still good by hooking the
leads to a battery and seeing if the motor operates. If it does, you need
to systematically work you way backward to determine where the problems
lies. Check the book for assistance.
http://www.jag-lovers.org/modern/xj40book/book_index.html You very well
may need to replace the resistors.

Just a note!! The car you are driving is now 15 years old!! MUCH that you
are going to run into for problems are going to be determined by the
maintenance that has been done over the past 15 years. Keeping drain tubes
clean is an annual (or more often) chore. I do it every six months on most
tubes -- the exception being continually for the top mount gas drain and the
top mount sun roof drains. I little compressed air and it all goes away
quickly. You can even use the compressed air used for cleaning computers.

Hope this helps

Webserve

> Hi,
>
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>
> - Tom

Reply to this Message

Chris Halpin - 20 Nov 2004 23:11 GMT

Hi Tom,

I have copied 2 previous postings that may assist you in resolving your
problems.

1. This related to an XJS Problem....
There are two sets of drains for the Aircon System.
The Plenum Drains run from the vent immediately in front of the
Windshield. These drain away rain water. They can become blocked by
dirt, dust and debris. If you lift out the black grill and pour some
water in you will see if it drains away or not. The hoses from these
areas are fairly easy to follow and clean out.

The other drains are the ones that usually block and you get wet feet or
wet carpets from. These drain away the condensate formed, when the air
is chilled.
To get at these is is necessary to remove the two covers from either
side of the tunnel. For each side; There is a vent in the footwell that
has 2 screws holding it and the panel in place. Behind this panel
towards the front of the car you will see a large hose section, just
under this is the drain. It consists of a short rubber section reducing
the diameter from about 5/8" to a 1/4" plastic tube. This tube then
passes through a rubber grommet to come out to the side of the gearbox.
This is where the blockage occurs.
Pull the rubber section away from the Aircon housing and pull it up out
of the grommet and you can then clean it out. This applies to both sides
of the tunnel .
A more permanent solution is to remove the original section of hose and
reducer and replace it with a piece of plastic tube that fits neatly
over the Aircon housing. You will find this fits neatly through the hole
in the tunnel wall without the grommet.
I have done this to 3 Jags I have owned and I never had another problem.

2. This relates to the electronic Printed Circuit Boards mounted in the
fans themselves.
NOTE: You may damage the Printed Circuit Board components by just
connecting the battery across the terminals. These fans are the
electronic controlled fans and they will not run with just the battery
connected.

I rebuilt both of my electronic boards using the components shown in the
article on the jag-lovers site.
http://www.jag-lovers.org/xj-s/book/acblower.htm
I was able to use the existing pc board as there was no damage apparent.
After assembling the components on to the pcb, I cleaned the flux off
and then sprayed the assembly with Clear Polyurethane as a protectant.
The rebuilt pcb was then mounted into the fan housing, as original. This
is advisable because the air passing the Transistor provides cooling.
I have had no further problems with the fans.

Chris

>Tom,
> I don't think you are going to like this.
[quoted text clipped - 89 lines]
>
>

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