Greetings Members, last week I did a favour for a friend by replacing her broken radiator header tank and topped up her antifreeze. it took us a day to get rid of the "low coolant level" message.
However, now a week later she tells me her air-con has only produced hot air ever since. She went to the air-con chappie who re-gassed her air-con system for her but it is still the same.
Can some one please politely suggest what I have done wrong or not done correctly or sufficiently?

Do I need to 'bleed' the water system of air, Is that why there is that small threaded cap in the top?

Look forward to hearing from you all.
DP.

PS. I tried looking on the S-Type threads but it would only allow me to view the first 2 out of 6 pages. Thanks.

Hi DP, yes you should bleed the coolant circuit but I suspect that has nothing to do with the air-con not working.

Did you undo any electrical connectors apart from the one on the header tank?

Hiya Dave, I only unplugged the sensor under the header tank. I did not touch anything else.
Question:- When you say "bleed the coolant circuit" I presume I run from cold with the small opening open and main cap closed?
Or...can you direct me to a instruction detail in this web site.
I am a recent new member and am still groping my way round the system.
Many thanks.. DaveP.

Hi Dave, well personally I wouldn't do it initially with the engine running, as that means the pump running and you will probably find that loads of coolant gets pushed out.

All you need to do is have plenty of the correct diluted coolant ready, open the header tank cap then open the bleed valve on the header and the other one next to the brake master cylinder, pour diluted coolant into the header tank until coolant free of bubbles comes out of both bleed valves.

Then close both bleed valves and run the engine for a day or two and check both bleed valves for any air.

The first question is why he "re-gassed" the A/C?

You only do that if it's low and that means it has a leak? Otherwise he should have just connected the gauges to verify the high and low side pressures were correct.

Any idea how much he added? If the A/C system pressures are to low or to high the cooling won't be right.
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Hi TBird6,
I am not sure why she went and got the a/c regassed.
Anyway, a week later she told me the air con was blowing cold air from the side vents and warm air from the top vents.
I expect to see her again this coming weekend, but as with the autumn coming on I don't expect she will be worried about having aircon working.
However, there is next summer and I hate niggling problems snagging on like this so I would like to solve it once and for all.
Do you reckon it could be that there is an air blockage in the waterway..? or is that just the sort of problem much older cars got.
Regards, DaveP.

That's the classic sign of a failed Dual Climate Control Valve (DCCV)....

+1 on DCCV (aka water heater valve)

Have a look at this

DIY: Diagnose It Yourself - JaguarClimateControl.com

Yes the DCCV is the prime suspect. But don't let her run the car with a failed DCCV.

We have found out most of them fail and start drawing too much current. This excessive current can take out the climate control module. Now it can be fixed so you don't have to replace the module but it's unnecessary if you change the DCCV in a short time.
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Make sure you didn't accidently pull the molex connector off the Dccv. I replaced mine and there are lots of hoses running thru that general area also.

You are correct Tbird6 I pulled the climate control module and found 4 copper traces burnt on the pc board, along with a new Dccv everything worked great

You can install protection circuits in the CCM so a bad DCCV won't burn it out again.
That should have been done by the factory!

Did you fix the CCM or just replace it?
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