134a conversion how much gas?

How many cans of 134 should I put into my 92 xj 4.0? I already changed the filter and have 3 cans with the conversion kit, but my ac sticker is gone. Thanks.

3 cans should get it going, but you may need a fourth to get the right pressure. I'd get the fourth w/o the oil -- too much oil will lock up the compressor.

You should be doing it by pressure and not amount anyway.

Charging with R134a

The system needs to be charged with a PT(press/temp) chart and a guage manifold.
According to the PT chart; the discharge air temp and R134a suction pressure should be: 40*/34.1psi, 45*/40.1psi, 50*/45.5psi, and 55*/51.3psi. The air temp at the condensor and discharge pressure should be: 90*/104.4psi, 95*/114.1psi, and 100*/124.3psi.
If you have an older system that has been restrofitted the watch the sight glass until the bubbles are almost gone and then add just a little more (good rule of thumb if you dont have a gauge manifold).
Hope this helps.

The system pressure varies depending on the ambient temperature, and I didn't have the chart handy when I replied which is why I wasn't specific. Still don't have it, but in general with R134a the pressure is up close to 40 psi (or over, sometimes). 3 cans in the retrofit kit will give you about 25 psi.

It's correct that you should be doing it by pressure, if you can.

Well last night I put 3 cans with oil in and the pressure gauge only read about 27psi, and the relief started to pop. The expansion valve sounded like it was ready to explode. I dumped the gas, and then put in two cans with oil and it is only reading 25psi, but the air is cold. I had the 15oz. cans. any help would be appreciated.

I have a saden(sp?) compressor... where in the heck is this sight glass everybody keeps talking about?

I just dumped in 3 cans... and it cools.