Dodge Repair: radiator overheats, dodge van, front wheel drive

Question
1992 dodge van (250).  the van overheats when we turn on the air conditioner, otherwise it runs fine.  do you know what might cuase this to happen.  without air we can drive all day. with air, it heats up.  steam comes from the radiator.

Answer
Wouldn't have a clue to be honest... You should have read my profile and instructions, I do not know anything at all about these RAM vans. Only front wheel drive stuff, like minivans and midsize passenger cars. My guess would be either a bad A/C or failing water pump.