There's high and low pressure switches I believe because my truck have orifice tube. I think the low pressure switch (on cold side, post evaporator) is bad so it don't turn off when the pressure get too low.
and technically no, overcharge don't make a/c colder. overcharge will act similar to undercharge (cycling, mostly due to too high pressure on hot side).
I plan to literally tear down my dash down to firewall eventually.... I will need to do that to put in the dash I got from you in like 3 years ago? Major job to replace the dash so I am holding it off until I have everything I'll need to do everything else while I'm there anyhow... heater core, evaporator, some hvac door actuators (none are broke right now but might as well replace the ones that's not easily replaced when all assembled, 20 years old now and 300k, so something has to give anytime soon) and rewire most, if not, everything behind the dash and possibly new, custom cluster to get my gauges off my a pillar.... I only can do so much...