? Pressure being released from AC?

Hi I recently took my 1997 Dodge Caravan SE for AC service. The shop told me that the AC passes Vacuum tests, however for some reason the pressure is being released. They did a dye test and found nothing. and suggested piece by piece removal which sounds and is a pricey option. Presently it has released all of the refrigerant and blows hot air and a bad odor. Has anyone heard or know what may cause this issue?

On another note the van runs great but I am noticing a revving sound from the rear of the van when going above 35 MPH. Any Ideas? Could it be the Muffler?

Thanks,

I’m suffering some hardships with my a/c on my 2000 GC. Takes a while to cool down the van. Not too much advise for you on this but I think I have an answer for your noise coming form the back of your van.

It probably sounds like a low, droning whine that increases in volume as your speed increases. It’s one of the rear bearing hub assemblies gone bad. Try to isolate which side it’s coming from, jack that side of the van up and spin the wheel/hub. If you hear a grinding sound that’s the one that’s bad.

I just had mine replaced for $300.00. It went bad after 90k miles. Hope this helps! Good luck.