Hello,

I had my AC recharged about a month ago and it was working fine until a couple of days ago. Every so often (not constant) I would hear a hissing from what seemed to be under the dash behind the steering wheel. Air got progressively warmer then not cold at all. Got it recharged again (under warranty) and have the same issue. Must be leaking freon, but is there an easy fix or am I in for a big bill?

Thanks,
Jim

 

For sure you have a leak. There is an easy way to determine where the leak is. There is a can of UV Dye that you can charge the system with, store bought self service can and this will leak a bright color where the leak is.

It can be anything from say the service port which get dirty and stick to a damaged line.

 

I hope your leak isn't in the cabin side heat exchanger. It is a bear to get to as you need to remove most/all of the dashboard. It isn't anything really difficult, but does take a lot of time and someone that is very meticulous as there are lots of connectors, screws, clips, parts, to keep track of.

Be aware there are other things under the dash that can make "hissing" sounds.

I recently also thought my 08 had a leak under the dash, but found it was the rear heat exchanger. Thought it was the front due a quiet hissing and that I couldn't see any UV dye anywhere. Turns out that the rear exchanger was capturing all of the dye right next to it and where you couldn't see until you took it completely apart. It was a corrosion failure across the inlet tube O-ring seat that allowed the coolant to leak around the O-ring.

You can try to hunt down the leak by first using UV dye in the system and running it for a while after a recharge. I recommend getting a high power (more than 1 Watt) LED UV flashlight/torch that is at 395nm wavelength or shorter. I use a 3 Watt 385nm unit that I got on eBay for about $20. It works extremely well, especially when it is somewhat darker out (mine is bright enough that I can see the UV fluoresce in sunlight). Be careful as there are lots of cheap junk UV/fake UV that is just blue lights out there. There are also coolant sniffers, but the cheaper ones are pure junk and a waste of time. The good ones are expensive enough that you might have second thoughts (I've seen them at up to $250 for the junk, ones that probably should work well start at around $350).