A/C no longer really cold - why?

I have a 2002 Chrysler PT Cruiser. The factory A/C worked fine for the first five years or so. But now it doesn’t get really cold any more, no matter how long I wait and not even on max (highest [4th] blower level, temp control all the way to the blue left). It seems okay in winter, but in summer the air is neutral, and on really hot days (over 85?F) the air is downright warm! The heating function and the circulation function and the inside/outside air mechanism all work fine, but the cooling function doesn’t any more. It seems that nothing was changed, either purposely or accidentally (no work was performed in that area).

First I double-checked that there was no fault code stored in the computer. Then I had the system fully recharged with new refrigerant. That made no difference (no surprise, as the mechanic had already told me the previous pressure was fine, and he couldn’t understand why I wasted my money on a recharge). Then I had all the controls (including vacuum lines) and connections checked. Then I had the blower motor removed to give some access to the insides, and all visible ducts checked for any detritus (such as one of those maple seeds). None of this turned up anything relevant or made any difference.

It seems to me it misbehaves like it would if the blend door was staying open a little. (It appears the blend door mechanism was redesigned after the very first models. I unfortunately don’t know exactly which version I have.)

Any ideas what the problem might be, or what I might do (or kludge) to fix it?

(According to both my mechanic and the shop manual, fully accessing the A/C on this car requires completely removing the whole dash and would cost a fortune. I can’t afford to spend more than the whole car’s resale value; that’s why I’m searching for anything a little simpler.)

The computer diagnostic system is to monitor emissions related items, not AC systems.
Frankly, you need to take this to an AC shop and get it diagnosed hands-on. This is not the type of problem we can diagnose from here.

I agree, a more talented AC specfic mechanic would have you an answer by now, wrong man on the job. The diagnostic approach to use here is “hands on” and I mean it literally. The mechanic should be putting his hands on certain sections on the AC system for diagnostic information.

Agreed; take it to an A/C specialist for an opinion. No one should have to rip the car apart to find out what’s wrong with it.

With the A/C running on max for a bit, carefully feel of the larger diameter A/C line at the accumulator, which should be near the firewall.
If it’s not cold then there is a pressure problem. If the line is very cold then it could be a blend door problem.

And make sure that the compressor clutch is engaged. (I would assume this has been done, but…)

Did the mechanic run a pressure check of the system? Is it possible you have a hole in the condenser?