I have a 1991 Toyota Corolla, and my ac cuts out after 10 minutes or so of driving. But when it does, it has a odd smell to it and it feels more moisturizer in the air. We’ve vacuumed and refilled the whole system and made sure there isn’t any leaks. I’ve also let some Freon out so there isn’t too much pressure. Nothing seems to work.
What are your system pressures? When the AC cuts out does the compressor still run? Is it an R12-to-R134 conversion? The smell might be mold in the air plenum.
H-200 to 250. L- a rough 40. No, the compressor shuts off and doesn’t come back on. But at night when it’s cooler, it works after shutting it off. And the coolant it needs is r12 but we did convert it to R134a.
Did you flush out all the old mineral oil and replace the drier when it was converted?
Pressures sound OK for R134 depending on ambient temperature so it's probably a control issue. That car is old enough that it probably has simple electrical controls, not a body module.
The low pressure cutoff switch could be going bad. Since you know you have enough refrigerant you could try shorting across the contacts for a short time to see if the compressor engages. (For that matter you can hotwire the compressor clutch and bypass all the controls.) There may be a high pressure cutoff and R134 does operate at higher pressures than R12. Another possibility would be an anti-frost switch that is malfunctioning. You need to trace out the AC control circuit and find any malfunctioning components.
A schematic diagram would be helpful - some libraries have those kind of reference books such as Mitchell's or even access to online services.