Heater Issues

[Jodxjr]

Hi All



I have had my 1999 XJR a couple of years - along with a few, let me
refer to them a idiocyncracities the car has performed very well and I
am very happy with it



I had a pre winter Oil and coolant change in August



The air con
has been a blessing throughout the summer - On my first journey out in
the cold this "winter" I set the climate to 24 and set off - After 20
minutes or so all I was getting was ambient cold air and occasionally
what can only be described as luke warm - Of course this gave the wife
every excuse to berate me for not having a descent car instead of this
old banger....etc - I bet you get the picture



I have topped the coolant up and still getting the same problems - Recently I have been monitoring the situation



1) It seems that the climate will heat the car from cold



2) The climate stops heating irrespective of if its set to 24 or Hi at
the point that the thermostat reaches half way - Never before - This is
with Air Con on with or without Auto or Air Con and Auto off



3) After it has reached its "point" it will not re-heat unless I turn
the car off for a while and then heats until the temperature reaches
half way. This I assume is when the thermostat opens



Questions



1) Is the half way thing a red herring?



2) Is there any change in the water circulation when the thermostat opens - I assume hot water comes from the engine block at all times



3) Is it possable when the thermostat opens the engine temperature drops to such a low temperature without moving the dash dial - In the slightest



4) Can the pump be faulty as i get glorious heat before the "point" - I
read a fantastic post on the pump replacement but can quite
catagorically confirm this operation does not fill me with too much glee



5) I have run the test on the head unit and it is giving me 41 42 43 and
45 - I cant seem to get rid of them - When I bought the car the heater
blowers did sound like Heathrow but i did some fishing and got some
insulation out



Any advice or experience appreciated



Cheers







Jod

[KEN33Y]

Would the thermostat be jammed open therefore, not allowing the temperature to heat up sufficiently. I have had the same sort of problem in older cars in the past