I have been experiencing AC issues for awhile so let me begin with a little history. Last year around August I took my truck to the dealership because the AC wasn't working. They recharged the system with the red dye and stated that the low pressure line was leaking and they had one in stock do I want them to replace it. So I stated yes. Well the summer was almost over so I didn't think anything about it because everything worked for apparently a month then the weather outside was cool so I didn't know. Then when things started to get warm around June of this year I took it back and they stated that they needed to replace the evaporator and the heater core and everything should be fine. So they did that and now two month later no AC. It gradually decreased in cooling meaning when I was turning higher RPM's it blew cooler than idling. Took it back again today and they replaced some line or hose that goes through the firewall. I drove home about 30 miles and turned the truck off and walked around the truck to get something out of the passenger side and heard a loud hissing sound under the passenger side fender while it was dripping apparently water. This lasted about 2 minutes and went away. Concerned that what they did didn't fix the AC issues I stated the truck again and it was blowing cold. Should I take it back to the dealer in the morning or is this normal. They socked me for over 450.00 today in which they stated it was fixed.

 

Mine always hisses for a few minutes after shutting down. Probably normal.

 

Hissing and dripping water at shutdown is normal.

 

Sounds somewhat normal. Remember when the A/C is running you have about 275 PSI in the High side (goes higher as the ambient outside air temp goes up) of the system, and around 30-35 PSI on the low side. When you shut down there is nothing to maintain the pressures (compressor). So the pressures will naturally equalize/balance themselves so the same pressure is on both sides (hi and lo). The high pressure can't go back through the compressor (check valves prevent that), so the only way for it to equalize is to go through what is called an orifice tube. The holes in the orifice tube are tiny (this is what makes the A/C get cold), so it takes a while for the hi side to bleed down and equalize. It will make noise as it bleeds down, similar to an air compressor with a leak, it make a hissing type noise to. The A/C sounds weird since the "leak" is inside of a tube.

The water dripping sounds normal. That also tells me that your condensate drain is not plugged (a good thing). Condensate water is part of an A/C system's normal operation.

Don't feel too bad, A/C problems are difficult to diagnose and sometime takes a few time to figure out exactly whats wrong.

 

Thanks everyone for your help! Your explanation jrs_dodge_diesel was awesome. Hopefully now my AC issues are gone for good. Well at least for a couple of years I hope!

 

The hissing sound , is caused by the orifice inside the tube near where the "hiss" is heard, like JRS said , it is just pressures equalizing inside the system.

 

Update: The weather was about 70 degrees here in VA last week for 2 days and I turned on my AC and BLAM no AC. Good thing I turned it on when I did because now it's in the shop again. It’s the fourth time now which it is being fixed under workmanship warranty. If I would not have checked it until this spring or summer I would have forked out another 400+ bucks. If anyone had anything done on their 2nd Gen or later AC -- check to make sure it is still working.

 

Might want to have the evaporator pulled and checked while there is no refrigerant in the system. The evaporator has been known to accumulate dirt and moisture, which leads to the tubes corroding and eventually leaking.

The evaporator is located in the blower box between the dash and firewall.

 

jrs_dodge_diesel - the heater core and evaporator was replaced and the some tube going through the firewall (Aug 07). The part that is now leaking is the tube going through the firewall at least that's what they are telling me. Maybe there was an issue with they way they replaced everything as I don't think it could accumulate dirt and moisture that fast to fail. I understand what you are saying though. What bothers me the most is this is the fourth time back to the dealership for the AC problem. I am like most all Dodge Diesel owners -- I love my truck, and want to keep it forever but without AC -- It can change one's mind if you know what I mean. Not to mention the problem with the dash cracking. DC will not fix that so I am on my own. I plan to keep it for another 5-7 years so maybe I will get it fix next as the agate color dash (top pad) is like $300 bucks.

Thanks for all of your valueable information.