mihnor details or major problem?

I have a problem with my car and I am having difficulty finding assistance. I hear water or gurgling in the dash area, smell antifreeze when the air conditioner is on and the air is very cold. Refrigerant was changed last summer from the R12 due to problems with the cooling system blowing warm air. I no longer trust mechanics with the car because they are not familiar with the engine. (7MGTE) and they can't find out what the problem is. Any suggestions?