Finally put my finger on why sometimes my scoob (MY02 STi7) will limp away at a standing start and other times will drive normally - the air conditioning!

We've been getting a roasting here the last couple of weeks with temperatures going up to 38-40 degrees daily so I switched the aircon on as even the air (what little there is of it) is hot!

Since last week, I'd noticed that my car had been running "off" - just not herself, with a noticeable lack of power at launch time. Yesterday, I switched off the aircon (which is set to the lowest/coldest setting with the a/c button on) and put down all four windows. The result? Instantaneous return of power. Tried my "theory" out several times just to prove I wasn't imagining things and sure enough, aircon on means loss of power.

Question: Is this normal?

I have an STi8 and I have noticed exactly the same symptoms along with quite an alarming noise (I mean a noise that worries me, not the sound of the alarm!) when the air con is running. Turn the air con off and the engine noise disappears and the power returns.

[Edited by EvoDraven - 6/24/2003 6:40:02 AM]

they all do that sir :D

Yes,

it's a well known "feature". You don't get smoething for nothing, and it does take a fair bit of power to drive the air-con compressor, typically about 10 - 15 bhp I believe.

At low revs, on a low compression turbo charged engine, there isn't much power being produced anyway, and a steady 10bhp makes a big difference to the available power.

The system is clutch operated, and if you fully press the accelerator, then the air-con should disengage giving you full power.

John

:( and just think what affect 10-15 bhp loss does for us Sport drivers!

'aircon off' is now laughing known as my boost switch :rolleyes:

Also, IIRC fuel consumption goes up by approx 12% when aircon is on

Thanks for the replies and explanations folks - good to know it's nothing I have to worry about.

EvoDraven - I also get a noise with the aircon on, sort of like a low whine, most noticeable when I'm stopped at the lights.

Redkop - increased fuel consumption with the aircon on would definitely explain why I've been filling up every two days instead of every three as usual, thanks for that!

Its not just a problem to scoobs really. It'll do it in most cars. If you're cruising along at constant RPM and shove the aircon on u feel the car lurch as the power is sapped.

Andy

yup, great fun when you are driving a 65bhp Clio Diesel!! :D I sometimes get scoob_babe to get out and push ;)

I thought the aircon gets switched off the second you accelerate ?

hahaha - cant believe you peeps hadn't figured out the air con system eats power. My sport wagon revs higher at idle, about 750rpm vs. 500rpm when I switch a/c on! :D

It's now known as my "rumble" switch at the lights. I have a full zorst setup but the sports are naturally quiet at idle, so if I feel like rumbling I hit the a/c button.

The A/C also switches off if you have the fan set to zero. flick the fan on and the A/c should kick back in.