I just bought a 1998 Ram, and theres a couple things that need fixing. One thing is a pipe that appears to have a leak. It is connected to the radiator, runs along the side of the engine bay and goes into the cab. Please let me know if you know what this pipe is. It makes an audible leaking noise when the air conditioner is run. If one were to run the air conditioner and then turn off the engine, it would make the leaking noise for about 15 seconds and then stop. The pipe is highlighted in red in this picture:



I need to know if this is a critical part in anything, be it the air conditioning or the cooling system in general. Also I need to know if such a leaking noise is normal or something a mechanic should look at. Thanks in advance.

 

AC line low side(pressure) are you sure its leaking ?mine makes a hissing sound after i shut it off /motor , its the system equlizing the pressure..

 

mine hisses too after you shut it off. its normal. its also normal for the a/c lines to frost over, and also drip condensation under the passenger side. if your A/C blows cool its ok.

 

+1 nothing wrong here, next question!