A Sanden SD7H15 compressor (very, very similar to the model used on late
model Vanagons) pumping R134a refrigerant consumes approximately 7.9 hp at
4000 rpm (compressor speed), 5.5 hp at 2500 rpm, and 1.7 hp at 700 rpm.  The
compressor runs a little faster than the engine due to small differences in
pulley sizes.  For a graph, see
http://www.sanden.com/support/pdf/SD7_brake_curve.pdf .

Ed

On Tue, 28 Aug 2007 19:36:15 -0700, Keith Ovregaard <kovregaard@COMCAST.NET>
wrote:

>I don't know if the vanagon compressor is sucking that much, but even
>so, it's no wonder the WBX'r drops rpm's when the compressor kicks in!
>Often times I shut it off to climb a grade just to get a little extra
>oomph and to keep the temps down.
>
>
>On Aug 28, 2007, at 7:09 PM, Rob wrote:
>
>> At  8/28/2007 05:51 PM, Keith Ovregaard wrote:
>>>  IIRC, most compressors rob about 5
>>> horse power from the engine.
>>
>> When they added a freon A/C compressor to the tailrotor drive shaft of
>> the HH-65A helicopter (it was an automotive compressor and this was in
>> the late 80's) they told us it took 14 hp to operate.
>>
>>
>>
>> Rob
>> becida@comcast.net