First, AC perssure 0 psi. Add 134 and bring psi up to 20 psi compressor ON, 90 psi on low port with compressor OFF. Whats wrong?
First, AC perssure 0 psi. Add 134 and bring psi up to 20 psi compressor ON, 90 psi on low port with compressor OFF. Whats wrong?
The compressor is probably cycling on and off, because there's not enough refrigerant. Did you make sure that you applied vacuum to the system before putting R-134A in? Did you also ensure that you reached the proper amount? It says on a sticker under the hood precisely how much to add. You need a proper set of manifold gauges in order to do this, and not use any from of a stop-leak. Working on air conditioners is complicated and not for any beginning DIY-er.
90 psi on low port with compressor OFF. Whats wrong?
There's nothing wrong, at least as far as the pressure you're seeing. You do realize that with the compressor off that you're going to see the same static pressure on both high and low sides of the system? That's fundamental.
You need a full gauge set to work on AC. If you're using one of those so-called "recharge cans" that only have a low-side gauge you really have no idea what's going on inside that air conditioning system and can wind up doing more harm than good.
