It takes about 2 weeks for my AC system to lose its charge and start blowing hot air. I had it drained, recharged, and a dye added. Can't find any leaks in the engine compartment. I had a new compressor put in two years ago.

Where else should I be looking? And do the evaporators go bad?

 

Look at the Valve core for the high side and the low side.
I replaced mine due to a slow leak.

Are you using a BLACK-LIGHT to find the DYE?

Didn't the AC shop check for leaks?


Good luck

Paul

 

The shop should have replaced the valve cores, but if they didn't for some reason then they will probably leak if original.

You should be able to see dye (yes you need a UV light lol). If you can't find any with UV, then it might be the core in the cabin. I assume that's not very accessible

 

Both my AC leaks were valve cores, first time I got a shop to replace it....that lasted one season, not sure what they actually did. Second time, I bought the cores and tool kit, took it to a friend with a body shop and the right equipment, he drained the system, I replaced the core myself and he filled it up......two seasons now, nice and cold.

 

My shop found a leak where a dye would still be difficult to find, in a pinhole on the tube to the evaporator. It's behind the instrument panel but my mechanic was able to get to it without pulling it.