A/C sucks way too much power

[vwmikel]

So, the story starts out that I bought this '95 318TI with an S50 swapped into it. The A/C worked, but the compressor was making some rattling/death howl type noises. It also took more power from the engine then you would seemingly expect. So, my assumption was that the compressor was probably shot and I needed to replace it. After replacing it the death howl is gone and it is smoother, but it still seems to take an exceptional amount of power from the engine. It is also noticeable when the compressor kicks on as you're driving.

So, with all that said, I'm wondering if others have the same issues and if not then does anyone know if there may be some compatibility issue here with the 6 cylinder compressor and the 4 cylinder evaporative cooler? I'm pretty sure the condenser is also the 6 cylinder one as it has the proper M3 radiator.

[fabiosouzajr]

I have the same impression on my 1996 328i, car runs so much better without the a/c... I also have the a/c compressor wierd sounds, wonder if just replacing the bearings would shut it up.. anyone???

[kalinrs]

Compressors take a lot of power by default. On the 4 cars I've had so far (4-6 cylinder, 1.8-2.8 liters) I could easily tell whether the AC is on or not. Driving around with it working for a while almost felt like a turbo boost once it is off.

On my 318, I intentionally turn it off when I stop at a light and it is uphill. If I don't, I might start rolling backwards or take 15-20 sec to get to 60 mph :)

Even on the M50 525i I can tell when the compressor cycles driving 70 mph on the highway. On the 328 it is not that noticeable but you can still tell. Sometimes using a higher octane gas helps bring the sluggishness down some.

[paniolo]

When I repaired my a/c my mileage took about a 10% hit.

[vwmikel]

So, it sounds like this might be somewhat common. The only car that I think I've ever had that sucked such a large amount of power for the A/C was a Rabbit GTI with the old piston compressor on it. It just seems odd for a more modern rotary style compressor. I'm wondering if I should stick the gauges on it and see if all looks well there as the machine we used to recover the A/C and then push the freon back in did not test pressure, only allowed you to work in quantities of oil/freon.

[r33p04s]

Yea the a/c sucks

[sk8er94803]

I agree, my 328is revs much more freely and seems to have a nice amount more torque with A/C off....sucks on hot days

[vwmikel]

I agree, my 328is revs much more freely and seems to have a nice amount more torque with A/C off....sucks on hot days

This is true. We've entered the time of the year where I don't really consider it optional during the day. From about October to May I'll just roll the windows down, but 100+ is a bit much in a black car.