My 2006 997 - weird air con and wipers issues

[Grahamr76]

Bit bemused by what happened today so thought I'd post it up for any thoughts. Trundling along at around 40 mph I had the aircon on Lo temp at a medium setting. I then gave the windscreen a squirt and the air con turned itself up for about 10 seconds close to maximum (although the number of dashes didn't increase on the control panel) and then fell back to its medium setting. Happened every time I washed the windscreen.

Any thoughts?

[anonymous-user]

It's an EMC (ElectroMagnetic Compatibility) problem. The wipers are generating some kind intereference which the A/C controller is picking up and the controller is getting temporarily confused. Soon as the wipers stop, everything returns back to normal.

As far a fix goes, I would suggest checking the earth points in the wiring for corrosion but you could spend a long time trying to fix this without success, calling it a characteristic instead is a lot less hassle.

[MB140]

Does the same happen if you just use the windscreenn wipers?

If not then you can isolate it to the pump side of the system not the wiper arm side.

[Grahamr76]

Thanks both. I'm not overly concerned about it so will probably just treat it as a feature 👍🏻 It's a 12 year old car after all. I'll see whether it happens when I just use the wipers.

Come to think of it, I've noticed a couple of oddities about the electrics and heating/cooling but I'll just live with it until something fails. For example when I close the sunroof sometimes it only closes half way then opens again. In winter if I turn the heating to maximum temp I can't then turn it down unless I turn it completely off and on again.

Anyway fantastic car, love driving it.

[The_Doc]

My sunroof does this. It thinks it's hitting an object so it reopens.
Oils the runners and reduce friction.
Cure