You guys seem to like diagnosing diesel car problems so. My car’s been fine for the 6 months I’ve owned it, a few niggles but it’s a 10 year old motor. But it’s all gone a bit wrong today.

Had to go to Swindon today, about 85 miles each way. Not relevant really but anyway. Noticed the car was only blowing hot air even with the temp set Low and A/C on, I’m sure I’ve seen posts about that so was (am) gonna have a search around then web when I got home – control valve issues maybe? However on the way home this evening something else happened that’s a bit more serious. Restricted Performance! And an amber light.
Besides the hot air the car was running as normal, temp gauge bang in the middle along a 50mph single road (A420 if anyone knows it), cruise on for most of the time behind a line of cars. First section of dual carriageway arrives I push the S button, leave the VW that’s been hassling and pass the queue, back off and the amber light comes on and the dreaded message. Stopped at the first opportunity, no adverse noises, turned it on and off a couple of time but the message remained. I drove the car home with no further issues besides the speed limit in each gear and a rather hot cabin.

So can the two things, hot air and restricted performance be related? And where do I start?

Got a cheap ELM327 reader and Engine Link on the phone and these can’t find any Trouble, Pending or History codes.

Thanks

Make and model may help!

And message

And what was the dreaded message?

Oil & coolant at normal levels?

Temp gauges are rubbish – many read fine even when the engine’s boiling it’s arse off.

parkesie – Member
And what was the dreaded message?

‘Here come the planes’?

S-Type.2.7D and the message is “Restricted Performance”. Basically limits revs & speed in each gear.

One of the few things the ELm shows is water temp at 85oC.

Yes. Affects my performance

Well I’ll start with the basics of your air con either needs regassing or your compressor for it is knackered or both hence the warm air only with air con on.
As for the engine going into limp mode, if the compressor is seizing and it’s causing belt drag it could be enough for the sensors to panic to stop you from ripping an auxiliary belt or worse still an engine destroying belt/chain as I don’t know the belt layout on a Jag.
Will it blow cool air through with air con turned off?
Leave it to cool, and check all levels in the morning and all header tanks etc for any tell tale head gasket leaks. If your air con runs off a single drive belt look at the state of the belt….if it’s looking cracked or splitting it may give more indication to the air con compressor seizing up as the gas in it contains a small amount of lubricant so run it with no gas you are running it with no lubricant. That’s my best educated guess but a professional may be along in a bit!

Thanks I’ll do the basic checks in the morning.

The hot (or cold) air only is a known failure, the heater control valve module can fail in either the open or closed position (hot or cold). The system pumps hot air when set to cold (no AC) with no variation as the temp setting is increased/decreased; with the AC on you can also feel cold air in the cabin – odd mix – from the demist vents. The AC was re-gassed 6 months ago and has been working since, including last weekend, the last time I used the can. I know it’s no indication of it fully working now. I guess the compressor may have failed, an old Series 2 I had did and the engine wouldn’t even turn over, but there’s no change (drop or hesitation) in the idle speed.
Diagnosis at the garage I guess.

Jaguar Climate Control Diagnosis website??

That’s today sorted 🙂

Nothing useful to add but maybe your car dislikes going to Swindon as much as I do and this was a protest?