1989 A/C problem 379

What A/C pressures are you seeing? Static and with the system operating?

Is the drain clear? Have run into issues in the past where the core would ice up within a minute or 2 and only blow warm air out the vents.

 

I would suggest to check for blockages in the A/C system. Sometimes, debris or other foreign materials can block the A/C system, preventing it from functioning correctly. You could try flushing out the A/C system to remove any blockages that may be present. You can also inspect the compressor. I had similar issue and to be honest you may want to bring your truck to a repair service center, I took mine to WallWork to diagnose and fix the issue. Good luck.

 

You didn’t list the blower motor on your check list. It may be weak or the squirrel cage may not be turning to blow air. Or dirt, leaves, rodents, or other things may have gotten in the box and plugged it up.

 

Just another thought. Since I noticed you are in Sweden. That should be a R134a system. Has the right freon been used? Not sure if that is available there? They are slowly phasing it out here and going to something else.
Heck. Being an ‘89 it may have been one of the last R12 systems, and in that case R134a never would blow cold in a converted R12 system for some reasons.