poor acceleration with a/c

[Keisari]

Last summer the missus' 2000 Echo (1.5L) felt quite happy to take the extra load imparted by the a/c compressor while in operation. However, we've been starting to use it again recently and the power drop feels really quite severe now. Yes, I do realise the 1nz-fe only makes 80kw and the compressor takes ballpark 10-15% of that, but the car now will virtually not accelerate on a flat road with the a/c on without either 1) pedal completely to the floor, or 2) overdrive on (edit: off). It's like towing a caravan. Also, there is occasionally a very rough 'clunk' noise when the a/c is turned on, which I am guessing is the clutch engaging in a somewhat violent manner (though I'm not sure what it's supposed to sound like as my a/c doesn't work :P).

The car is very regularly serviced at a dealership and the compressor was rebuilt only a few years ago. What sorts of issues does TOCAU think might cause such a condition? Bad a/c clutch? Alternator? The battery was replaced about 12 months ago, though there is a bit of copper corrosion on the terminals.

Thanks in advance.

Edited November 9, 2009 by Keisari

[Mole]

I don't know why your loosing so much acceleration / power, but assuming its an auto (after mentioning overdrive), shouldn't you always keep overdrive on? You'll loose a lot of fuel economy if you don't use your overdrive gear and I don't see any reason to not use it.

[Keisari]

Right you are, my apologies. I meant to say overdrive OFF... it won't accelerate properly unless overdrive is off.

And yes, automatic.

[Speedz]

i always rev my Yaris so its isnt sluggish... (its a manual... :D)

[rob323]

If it still drives fine with the AC off, then I would be looking towards the compressor and AC system.

Does it throw the check engine light at all?

When was the maf last cleaned?

When was the auto last serviced (full flush and filter change etc)?

[Kichy]

I am having the same issue with my Echo, and that's a manual.