I think you're just a bit low on freon.
20 psi will trip the low pressure switch and it needs more than 40 to reset.
The specs from Dodge from the 2000 FSM say: Opens < 24 psi +/- 1 psi. resets 39 psi +/- 2 psi.
The high pressure switch should be fine. Opens: 450-490 psi, resets 270-330 psi.
In 2000 Dodge specs a high side pressure, at 100, of 220-260 psi. You're there.
The 2001 FSM gives better information, and different pressures. At 100, High side: 290-390 psi. Low side: 35-45 psi.