I used to frequent an AC shop in Evangelista St. in Makati. They use a gas canister with a small flame to trace freon leaks. When the flame sniffs even a trace of freon, it changes color. The owner, a fil-am retiree, said that he personally brings the stuff from the US. He is a nice guy to talk to and is very helpful.

The shop is located along Evangelista st. near the corner of Arnaiz st in Makati. Forgot the name of the shop but if you are coming from Arnaiz st. it is on the right side. The frontage is very small but there is a nice big working area at the back.