i know very little about the air conditioning sytem besides the basics, now it seems every body is asking questions about their ac system and mostly about how to refill it. Everyone else is telling them to get proper gauges and find the pressure to where there car is full with refrigerant, Now i don't no about you but having some 134a in the ac is better then none right. Now the walmart gauges says a 25-45 psi reading means the ac is full i just want to know and clear up for safety reasons does anybodys ac system take a fill at less then 45 psi. i just want to know if our ac systems are aleast good for up to 45 psi. if anyones is lower then this please respond and leave your psi number

mines around th 60 rang on the gae i got from Advacned Auto

You should really get a manual and get to understand the HVAC system a little better before you start working on it. I have a Haynes Automotive HVAC tech book, not the best but it works.

Your low side should be a lot lower than 40psi because at 40psi the evap temp would be close to 60*F meaning no cooling, but i don't remember what my low side reads. The high side should be in the 170-210 psi range on an 80 degree day.

The refrigerant capacity is 2.42 lbs. If your system is completely empty, make sure you draw it down to a complete vacuum to remove moisture from the system before recharging.

Higher pressure isn't better, nor is lower pressure. You want to be around 30-40 psi. Lower than 30 isn't good, nor is being over about 50 psi. 40-50 is okay, and usually results from the compressor being turned too slowly at idle.

You don't chage A/C based on pressure, you measure the weight of refrigerant being put in. An A/C system could have a rest pressure of 130 psi on a hot day, yet have only 1/4 pound of 134a in it. It could also have a rest presure of 40 psi on a cold winter day and be overcherged.

If you compressor is cycling very quick: 3-5 seconds, it'* low and needs to be recharged. It should stay on for at least 15 seconds or so before shutting off.