Air conditioning gradually stopped working, hissing noise

Question

On my 2003 Kia Sedona minivan, the air conditioning recently stopped working. This occurred somewhat gradually over the course of a week or so.

I noticed today that if I turn the air conditioning on, I can hear a hissing sound which seems to come from the center of the console, or near the passenger side.

No noise occurs with just the blowers, and noise is consistent no matter what blower speed. After turning off the air conditioner, the hiss doesn't stop immediately, but takes a few seconds before going away, even after I hear the compressor disengage. The recirculating selector has no effect on the hissing sound at all.

Do I simply need to get the refrigerant recharged, or are there other things I should be looking at?

Answer 1

It sounds to me that a leak in the refrigerant lines is a likely culprit.

It gradually getting worse would be the gradual loss of the refrigerant as it leaked out.

The hiss you are hearing now I would suspect is pressure created by the compressor being engaged and coming out of the point of the leak.

If you just get it refilled, you will probably end up back in the same state, the leak needs to be found and fixed.

There are some A/C leak sealer products out there, I have no experience of how well they work and even then, every leak is different. Since yours leaked out slowly, I'd say one of those products might have a chance of sealing it up.