B737 Captain was informed that the start cart; required for the left engine start; was positioned in front of the left engine. Ground crew advises that they are not aware that the cart should be positioned on the right side for a B737 air start.

Narrative

Our aircraft had an inoperative APU and a ground air start cart was required for engine start. The 737 procedures specify starting left (#1) engine first and all start equipment positioned on aircraft right side. During the walk around; the First Officer noticed a start cart on the LEFT side of the aircraft in front of the engine we would be starting. Ramp was notified and moved the cart. However; upon review of the procedures with the ground crew and ramp supervisor; it was discovered that they are trained to put the start cart on the left side of ALL aircraft and don't differentiate for a 737. This problem also occurred [during the preflight for the second leg]. The ground crew once again informed us they had no knowledge that the start cart had to be on the aircraft right side as we were going to start number one first. I think this is a systemic issue and could result in a problem for a crew that is unaware; but assumes the start cart will be positioned properly by the ground crew (who might be inadequately trained).