My OBD for climate control shows me that low pressure switch is open. It is on 93 90CS. Where is this switch located? I understand that system is probably low on freon(R12), but would like to hear what are the most common leaking points on those cars before dealer will try to put his hand on my cash.

The a/c low press sw. is located up against the firewall, infront of the ECU, up above the passenger's toes. You have to remove the ECU to get at the low-pres-sw.

The evaporators are notorious for leaking.

Checkout link-

The picture of the "a/c box" shows the low press sw. Also where the ECU goes.<ul><li><a href="http://home.ec.rr.com/miktip/maintenance.htm">http://home.ec.rr.com/miktip/maintenance.htm</a</li></ul>

Thanks, looks like I have little project to do.
Is a dealer the only source of those parts or someone makes them better and they last longer.