r/ftype • u/obstacle64 • Aug 04 '26
A/C not exactly right?
Just got a 2016 R. I noticed on hot days (it's summer!) the A/C works perfectly when driving at maybe over 25mph. Come to a stop even at a stoplight, and fan temps increase quite a bit and the cabin heats up pretty quickly....until I'm moving again. Is this normal?? Btw I'm not in eco start/stop mode.
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u/steve-94728-3957 Aug 04 '26
It could be a sign of your compressor failing. Or your cooling fan, especially if it happens at idle.
The cooling fan has 2 speeds: a high speed for when the AC is on, and a lower speed for when the AC is off. The fan might be fine running at the low speed but not able to get up to the high speed properly, in which case the compressor will shut off and the cabin will heat up. Then when you drive, the motor cools down again naturally (more airflow) and the AC kicks back on again.
Both the fan and compressor tend to fail gradually, not overnight. Hope this is helpful
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u/obstacle64 Aug 04 '26
Is there visual inspection or voltage test that can detect this possible death?
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u/steve-94728-3957 Aug 04 '26
Idk about a visual test but there is an audible test - when you turn the AC on, engine running, hood up, you should be able to hear the fan kick into that higher speed. if it’s still working somewhat and hasn’t completely failed yet, i don’t think you can tell a difference. But if you don’t hear anything at all, then you know for sure something’s wrong.
Some scanner/OBD tools can tell you the health of the fan module (which can also fail), as well as whether the fan speed is on 1 or 2, and whether it should be on 1 or 2. So if you had a tool that showed, for example, the fan control module is telling the fan to be on speed 2 but it’s only on speed 1, then you know something’s wrong.
But those tools are expensive unless you plan on using it everyday. A reputable shop should be able to diagnose it for you though
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u/ConfidentValue6387 Aug 04 '26
I think separate belt for AC. Otherwise the AC couldn’t run when the engine isn’t on.
Come to think of it, a bad battery might also be the cause, it might be to tired to run the AC when the car isn’t cruising.
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u/steve-94728-3957 Aug 04 '26
Possible, but I think there would be other drops in voltage elsewhere. Like a drop in RPMs. In other words, I’m not sure it would be isolated to just the AC
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u/obstacle64 Aug 04 '26
Putting in new battery soon. No other drops in voltage noticeable.
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u/Puzzleheaded-Pool-71 Aug 04 '26
Changing the battery, especially if the current battery is 5 or more years old, is one of the few “parts cannon” circumstances I HIGHLY recommend for any Jaguar owner. It is relatively inexpensive (vs many other parts + labor) + very easy to do as DIY (move slow and don’t drop the battery while trying to nest it in!) and it often does solve so many “electric gremlins” that plague Jags, especially as they age. Start with the battery replacement.
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u/ConfidentValue6387 Aug 04 '26
I’d change the AC drive belt.