AC leak testing

[tashirosgt]

I want to leak test the AC on my 89 Corolla with one of those florescent dye kits. The AC was converted to R134a several years ago by the dealer. If the pressure is low because much of the refrigerant has leaked out, will the dye can raise the pressue enough for me to do a good test? Or must I add more refrigerant to bring the pressure up? (That seems like a waste if there is a leak. )

[fredk]

how much pressure is in it now?

[SBS]

I've done AC work with the dye and for a do-it-yourselfer it can sometimes be more trouble than its worth.

On my pickup I had a leak on the compressor. Like you, the pressure was low so I had to add freon just to get the dye into the system. Well the fan ended up blowing the dye everywhere and it was very hard to tell where it was coming from.

Here is a better way to do it....

Go to Harbor Freight and get a 134a vacuum pump and a set of gages. Find a friend with a big air compressor and use the vacuum pump to vacuum out the system. Then watch the gages to see if air is leaking back in. If you have a leak then it will. Then all you have to do is use a good ear to listen for the leak.

If you can't hear a leak, try this: Get an o-ring set from Autozone (about $6) and change the o-rings. That is a common source of leaking and its something you'll want to change anyway. Vacuum it down and see if it is still leaking. The IMPORTANT PART of using the vaccum to test for leaks is that you don't have to blow $15 on freon each time you try to fix the leak. You'll know if you've fixed it before you add the freon.

You'll need the vacuum pump and gage set to properly refill the system after you replace whatever is leaking.

-Sal