199 Grand caravan

Does anyone know exactly where the low side service port is on the Grand caravan a/c system? There is a thick tube going down into the compressor in the very front of the van. it has a port that the a/c recharge nozzle fits but it won't allow refrigerant to be put in.

If the recharge nozzle fits the port and not the other then that is the place to put the refrigerant into the system. Newer recharger parts will only fit the correct port. Did you try to recharge with the compressor running or off? Try running the van to that should allow it to take the charge.