[xj40] It's not all bad

I recently got around to sorting scrappers blower problems ,
basically they only worked on full speed or nothing as is
common .
I acquired a set of replacements from a '94 model which will
fit but you need the two link leads [still available form
jaguar] as they have different connectors .

All appeared to be fine at first , blowers now work on all
speeds , more recently I’ve discovered that there is a
problem and i’m not quite sure what it is .

On defrost hot air goes to the top vent and side vents, a
very good flow too and flow to the footwells shuts off as it
should , the temperature control will send hot or cold air
to the footwells as required .

The one thing I can’t get is cold air to the side vents when
on full cold setting , I still get lots of hot air , there
is also no flow to the centre vents .

Am I right in thinking the upper blend flap is stuck in the
full hot position ? , if so which side is it on so I might
try to release it with a judicious clout .

It did use to work but since a spell in hospital for an
operation it now doesn’t ,

Derek…–
Derek, kent '93 Daimler 4.0L solent ,'93 4.0L,westminster .
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In reply to a message from happyshopper sent Tue 29 Sep 2009:

Derek,

Certainly sounds like a stuck upper blend flap. I’ll send
you some pictures via PM to help you ‘clout’ the correct item!

You also say ‘‘there is no flow to the centre vents’’.

Do you mean that they are not opening at all when you select
A/C? If so, you have a separate vacuum problem.–
The original message included these comments:

The one thing I can’t get is cold air to the side vents when
on full cold setting , I still get lots of hot air , there
is also no flow to the centre vents .
Am I right in thinking the upper blend flap is stuck in the
full hot position ? , if so which side is it on so I might
try to release it with a judicious clout .


Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
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In reply to a message from Bryan N sent Tue 29 Sep 2009:

Ah now , the aircon on scrapper has not worked since i
acquired her , I think it probably run out of gas and was
never filled , she was in a bit of a neglected state when
bought her .
Having said that I could always get a good flow through the
centre vents during the summer albeit not chilled , I have
tried putting the aircon ‘on’ at the control and both red
lights will light up but of course the compressor doesn’t
engage hence my thinking that it’s low on gas , but as i
still had airflow through I haven’t bothered with it , i
haven’t looked to see if they are opening but I would think
not as I have plenty of flow everywhere else .

I did also think I might have an ECU problem that was not
opening the upper blend flap as i’m not certain that the
cabin temperature is being automatically controlled as
yesterday the car was getting hotter and hotter yet the fans
were not slowing down , so I may have more than one problem .

After being cold last winter in her I can put up being too
warm this year but I would like to get it right ,

Derek…–
The original message included these comments:

In reply to a message from happyshopper sent Tue 29 Sep 2009:
Derek,
Certainly sounds like a stuck upper blend flap. I’ll send
you some pictures via PM to help you ‘clout’ the correct item!
You also say ‘‘there is no flow to the centre vents’’.
Do you mean that they are not opening at all when you select
A/C? If so, you have a separate vacuum problem.


Derek, kent '93 Daimler 4.0L solent ,'93 4.0L,westminster .
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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In reply to a message from Bryan N sent Tue 29 Sep 2009:

Thanks for pointing me in the right direction Bryan , i’ve
tried the judicious clouting to no avail , the centre flaps
are definitely held tight shut but can be moved by hand .

Vacuum is good and all lines seem to be in place , i’m going
to have a go at swapping the ECU as soon as I can source one
as the signal to open the vents may be the problem , at
least i’ll have a warm winter

Thanks Derek…–
The original message included these comments:

In reply to a message from happyshopper sent Tue 29 Sep 2009:
Derek,
Certainly sounds like a stuck upper blend flap. I’ll send
you some pictures via PM to help you ‘clout’ the correct item!
You also say ‘‘there is no flow to the centre vents’’.
Do you mean that they are not opening at all when you select
A/C? If so, you have a separate vacuum problem.
The original message included these comments:

The one thing I can’t get is cold air to the side vents when
on full cold setting , I still get lots of hot air , there
is also no flow to the centre vents .


Derek, kent '93 Daimler 4.0L solent ,'93 4.0L,westminster .
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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In reply to a message from happyshopper sent Tue 29 Sep 2009:

Derek,

If you can get to the 6-way white connector on the solenoid
valve block, you should be able to see 12 volts on pin 4 on
the Slate/green wire from the ECU but only when A/C is
selected on the panel. Check also that you have a good
ground on the Black wire from pin 2 of that connector - it
is a common permanent ground (stud behind ‘J’ gate under
centre console) for the recirculation and coolant valve
vacuum solenoids as well as the centre vent solenoids. Is
the coolant shut-off valve working OK to close when A/C is
selected?
That same ground wire is used by the in-car temperature
sensor ‘aspirator’ fan motor - I wonder if that is working?–
The original message included these comments:

tried the judicious clouting to no avail , the centre flaps
are definitely held tight shut but can be moved by hand .
Vacuum is good and all lines seem to be in place , i’m going
to have a go at swapping the ECU as soon as I can source one
as the signal to open the vents may be the problem , at


Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
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In reply to a message from Bryan N sent Tue 29 Sep 2009:

Aside from just seeing the fan spin, is there a way to test
the aspirator’ fan motor and correct signal?–
The original message included these comments:

sensor ‘aspirator’ fan motor - I wonder if that is working?


John 90 XJ40
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In reply to a message from Bryan N sent Tue 29 Sep 2009:

Bryan you raise a couple of interesting points as a couple
of times this year I have thought the coolant shut off valve
was stuck open and took a bit of coaxing to stop the heat
building up in the car , in fact I had hot air coming
through the centre till it sorted itself out , even then the
air was still warmer than outside ambient .

I also have my doubts about the aspirator motor as i’ve
never experienced it running so I shall investigate that , i
presume it runs permanently to detect temperature .

I’m aware of the ground stud you mention and shall check
that , i’m not familiar with the solinoid valve block , i
presume that’s where all the vacuum pipes meet ?

Anyway you have given me plenty to investigate and i’ll work
my way round these things , [ i’m still recovering from a
shoulder arthroscopy ] so I can only proceed slowly if at
all , but while there’s things to investigate there’s still
a chance i’ll fix it in the end ,

thanks Derek…–
The original message included these comments:

If you can get to the 6-way white connector on the solenoid
valve block, you should be able to see 12 volts on pin 4 on
the Slate/green wire from the ECU but only when A/C is
selected on the panel. Check also that you have a good
ground on the Black wire from pin 2 of that connector - it
is a common permanent ground (stud behind ‘J’ gate under
centre console) for the recirculation and coolant valve
vacuum solenoids as well as the centre vent solenoids. Is
the coolant shut-off valve working OK to close when A/C is
selected?
That same ground wire is used by the in-car temperature


Derek, kent '93 Daimler 4.0L solent ,'93 4.0L,westminster .
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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In reply to a message from John S sent Tue 29 Sep 2009:

John,

Is there an ‘aspirator’ on your '90 model? I can’t see one
on the circuit diagrams - there appears to be a solid state
cabin temperature sensor but no fan.

On the '91 /'92 models there is an ‘aspirator’ fan which is
provided with ignition-switched power from fuse #9 in the
centre fuse box as soon as the ignition is turned on, so it
should run all the time the engine is running.

[On '93 / '94 cars the ‘aspirator’ fan receives
ignition-switched power from fuse #7 in the centre fuse box]

I don’t know of any formal procedure for testing the cabin
temperature sensor circuits for the effect they have on the
HVAC system or just to see if they are working, but I guess
one could improvise(!) :slight_smile:

How about setting the panel to mid temperature and then
playing the wife’s hair drier on the aspirator / sensor
intake? In ‘Auto’ mode, that should cause the A/C to come on
full blast to cool the cabin down!–
The original message included these comments:

Aside from just seeing the fan spin, is there a way to test
the aspirator’ fan motor and correct signal?


Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
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In reply to a message from Bryan N sent Tue 29 Sep 2009:

I have a fan that sits under the right side knee bolster, on
top of the shelf above where your feet reside. I am
assuming that is the fan aspirator fan that you speak of.

It spins and has a round black cover with holes where it
sucks/blows air.

I notice that when I first turn the AC on / first time in
the morning I get a lot of blow. Then the hard blow rather
quickly disappears.–
The original message included these comments:

Is there an ‘aspirator’ on your '90 model? I can’t see one
on the circuit diagrams - there appears to be a solid state
cabin temperature sensor but no fan.


John 90 XJ40
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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