I have had low heat output from the heater on my 1998 Sovereign
4.0 for some time, fortunately the winters have been reasonably
mild. This problem has now become a quest to resolve.
I have had the cooling system drained, flushed and refilled.
There are no leaks.
Engine reaches normal temp very quickly.
There is no under or overheating of the engine.
The electric heater pump is new.
Only get heat when running engine above 1500 and A/C switched
off.
I have read most everything and can confirm that when the
electrical connector is removed from the valve there is so much
heat I have to turn A/C controls to less than 20 C.
I understand the valve operation is the action of an on/off
cycle at varing rates dependant on interior temp setting.
Voltage at the vale being switched from 6.75v - 13.75v where
6.75v = open and 13.75v = closed.
I currently have the valve disconnected from any power supply
so quite toasty in the cabin now. Will be checking the
voltages this weekend.
It appears the valve is being powered on at all times, which
could mean either permanent 13.75v or solenoid in valve is
responding to both 6.75v and 13.75v as engage.
I need to know if this is likely before I embark on dismantling
as it’s not the most accessible area under the bonnet.
Also can someone advise if this is a regular problem that would
benefit from a new valve or a known good secondhand.
Many thanks
Barrie–
1998 - Jaguar Sovereign 4.0
London, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from XJ Barrie sent Thu 3 Nov 2016:
The solenoid valve is OK if all is well with it
disconnected as it defaults to open! IIRC the termistor on
the cabin temp. sensor which is mounted on the small fan
unit located in the footwell cowl adjacent to a UK drivers
right knee may be the problem and or the fan may be
blocked with crut/dust, if that is OK you’ll need to look
at the circuit and it’s relationship to the CCU.–
The original message included these comments:
Also can someone advise if this is a regular problem that would
benefit from a new valve or a known good secondhand.
In reply to a message from XJ Barrie sent Thu 3 Nov 2016:
Neil could be heading down the right track but the
thermistor on the X308 is located to the lower right of
steering wheel behind the little grill that has the ‘boot
open’ button in it.
You need to remove this carefully as their is a small fan
and trunking which blocks up with crud affecting it’s operation.
BTW…have you done a fault diagnosis sequence with the
climate control to extract any codes?
Maximus–
The original message included these comments:
I have had low heat output from the heater on my 1998 Sovereign
4.0 for some time, fortunately the winters have been reasonably
I have had the cooling system drained, flushed and refilled.
There are no leaks.
I have the exact problem with my Sovereign ??? Im going to chech the little fan first thing in the morning. In the x308 there isnt a dedicated fuse for it but other forums have said F15 in the engine bay, (big fuse box not the engine smal box) although when driving at normal speed I do get heat in the cabin but if left to idle she goes cold again.
Maxwell, thanks ever so much for your picture projects on pbase. They have been a great help mate thanks.
You need to find and read TSB 303-11 Amended.
I can’t post it here because it is a .pdf not an image.
I have posted it on other forums. It is the recommended procedure we used at the Jaguar Dealer to determine the fault and remedy the problem.