My air con was re gassed in January this year and has worked faultlessly since. System pressurised ok when it was done. Yesterday when I switched it on the engine revs at idle increased with every click of the blower switch. With the heater on full it was idling at 1100 rpm. I drove to the shops and tried it again, it was the same. Came out of the shops it was the same again, drove home tried it again and it was back to normal, turn the blower up and cold air but no increase in rpm.
Any ideas what can cause this? Is something starting to fail? Any input would be appreciated.
I have no fault codes present
Thanks in advance

Probably doesn't increase the revs if the engine is warm

Good point, never thought of that. Just was a bit of a shock when I took my foot off the brake and it reversed up my drive without touching the accelerator. Doesn't normally do that as its on a bit of a hill, but you are probably right.

Tried it this afternoon from cold, and it has behaved itself. No increase in rpm at all, Maybe its just one of those range rover things.

wonder if its a low voltage problem.

check the voltage when you are doing this.

What was the ambient temperature?

On very hot days, the PCM will increase the engine RPM to maintain the required cooling inside the car

I have only noticed it in 30+ degrees, in my car, but the AC is normally quite cold anyway

Battery is new, and haven't had any other power issues. Temperature was 28 degrees, I have never noticed anything like this before on any of my other cars, or on this before. But I only drove it occasionally before I took full ownership of it. Its been fine ever since, but temperatures have been cooler.