idle dropping with AC on

[Paul V]

Do they all drop when the AC is switched on? Just notice the revs can get as low as 5-600 rpm, I raised the idle speed yesterday but most modern cars have a idle boost when the AC is on. Does the Tuscan and mines just not working or is it normal for the revs to drop?

[andyoleary]

Hi,

The rev's will drop when the AC is on - mine drops about 100rpm but normally idles at around 900 so it is not a major issue. When the fans come on (both of them) I do see a slight idle boost (50-100rpms) but not with the AC on - I think this is because the fans are ECU controlled whereas the AC isn't, could be wrong though.

Andy

[nelly1]

There is no idle boost because the idle speed is not governed or controlled by the ECU - there's no idle speed control valve or similar - it's set only by the throttle stop screws.

[NCE 61]

The idle speed on mine also drops by about 100 RPM when the A/C is switched on, although do get the idle speed increase when the cooling fans cut in, there must be somthing in the ECU that controls this.

[Paul V]

did seem better today after tweaking the idle yesterday, hopefully that'll sort it