AC Recharged Too Much Pressure?
 

I just recharged the AC on my '99 F150 5.4 Liter today. I used the easy can from Wally World that had the gauge on the hose so I could see what the pressure was. By the way, my A/C has a tiny leak and I have to get it recharged every couple of years, my outstanding mechanic used the dye once but couldn't find any leak, he said the molecules are so small in the R134 that it easily escapes a very tiny hole. Anyway, I plugged in the handy little hose to the collector on the firewall in what appeared to be the one and only proper sized valve right on the collector. The gauge indicated that the level was right on the line between low and full. So, I figured it needed a little recharge and commenced to push the button on the can. The gauge shot up quite quickly to the area that said "warning" and not too far from the "alert" section of the gauge. The pressure read at about 65 pounds. So, my question is, have I gone and overfilled the darned thing? Am I going to have problems as a result or will it be alright if I just go on and leave it the way it is? Any advice would be great. I sometimes question the instructions in these kind of scenarios but I don't want to cause damage through a lack of concern. Thanks.

hmm good question, I know a lot about home, and commercial a/c but auto hmm 65psi on the low side would be a temp of about 64 degress to much freon, the gauge In my guestamate should be about 31-33psi so the evap temp would be around 36 degress, remember I dont know auto a/c, but i hope i could help, Is it blowing cold air?? or is it warmer now than before?

Yeah, it's blowing cold air for sure. Before I did the recharge it was blowing moderately cool air, but this particular pickup has always been able to just about freeze me out of the cab in all kinds of hot weather, that's why I dove into the project.

Are you sure that the pressure reading on the gauge is from the system. Have seen those valves get sticky and not flow properly. Maybe when you pushed the charge button the system did not take any freon and it just pressurized the hose. Find it hard to beleve that a few ounces of freon in a system that holds a pound + is going to cause such a huge change in pressures. If you have a cronic leak it might be worth the $ to invest in a gauge set with the proper adapters. the gauge on those quick fill cans are prob. not of the highest quality. Don't forget that temp and humidity will also affect system pressures.

open the windows ,set on max high fan... take rpm to 1500 and hold there...now what does it read..in the green your ok

I think you hooked hose to wrong valve. Did you hook it to valve on firewall drivers side ? On my 99 5.4 it has a green cap. If you did this is not the a/c system. The correct location is on passenger side below the reciever ( black can covered in rubber insulation) this is the low side charge port. Hook hose to this and charge system.

You were reading the pressure FROM INSIDE THE CAN!

You have to shut off the valve on the can to read the pressure in the system.

Steve