Jim~

That depends…It can be a process…

Sometimes you may not show a bubble on one joint when cooling…But it may show on that same joint when heating…

It's all about what tube/joint is under higher pressure when in either cooling or heating…High side…Low side, and that changes by "Reverse Cycle"….And yes…heating that joint can make it show too…

You can spend Many hours (and a lot of 409) trying to find a leak with just bubbles….It's best to get someone with a sniffer to at least get you into the general area…Even then you may not be able to see a bubble if it's on the back side of a joint you can't see….

Leak detection is no less than a tedious process, and sometimes called an art…

Steve~