AC system pressure?

[BAH2SS]

So where I live the ambient temperature is around 40-42 degree C. had a leak in my low pressure port valve and had it repaired already, the mechanic/technician charged my ac system and had it around 30 psi showing on the gauge but I am 100% sure I've seen it before at 40 psi when used to be cold though the mechanic says 40 is overcharged!!. It is not blowing as cold as it used to and I am guessing I am short on Freon.

Anyone has any idea of how much should a fully charged system pressure sit at for our cars?

[Black_SS10]

Evac the system add refill for accuracy. 1.32lbs or .6kg r134. Add PAG oil if needed.

[BAH2SS]

Originally Posted by Black_SS10

Evac the system add refill for accuracy. 1.32lbs or .6kg r134. Add PAG oil if needed.

Thanks for the input, the question is there are two sides on the ac system, low pressure and high pressure.
Low pressure side is used to recharge the system, how much should the system pressure be ?
0.6 is the freon capacity

[Black_SS10]

Originally Posted by BAH2SS

Thanks for the input, the question is there are two sides on the ac system, low pressure and high pressure.
Low pressure side is used to recharge the system, how much should the system pressure be ?
0.6 is the freon capacity

You said in your original post you weren't sure if the system was properly charged or not. The pressures won't matter if the system isn't filled properly. Also, the ambient temperature will affect the pressures. In order to properly measure the running pressures, an AC manifold gauge set needs to be hooked up to the low and high side. Both sides need to be checked. I would rule out low refrigerant by doing an evac and recharge with the proper amount.

[PowertoLove]

These small systems are VERY sensitive to the amount of charge in the system. If you are trying to set it up using pressure as a guide there are ALOT of things to consider that makes a huge difference in how cold the system will be. TOO many for a inexperienced person trying to get it right.

I 1st of all would do as Black_SS10 suggests BUT it has to be weighed in or very carefully put in that have the proper amount and the system need to be COMPLETELY EMPTY.

I had poor cooling performance in mine and the pressures looked good. I had to let refrigerant out of the system because someone over filled it. Another problem you may have is the EXSPANION valve. If its not working properly it will never be cold and its hard to diagnose on these cars. If the system is charged properly, the compressor is working properly and the pressures look good the expansion valve may be the trouble OR moisture in the system. The proper way to charge the system if it was open to atmosphere for more than a few hrs is to replace the desiccant bag then vacuum the system before charging. Doing it any other way will fail. Good Luck

[PowertoLove]

Originally Posted by BAH2SS

So where I live the ambient temperature is around 40-42 degree C. had a leak in my low pressure port valve and had it repaired already, the mechanic/technician charged my ac system and had it around 30 psi showing on the gauge but I am 100% sure I've seen it before at 40 psi when used to be cold though the mechanic says 40 is overcharged!!. It is not blowing as cold as it used to and I am guessing I am short on Freon.

Anyone has any idea of how much should a fully charged system pressure sit at for our cars?

Look at this chart but keep in mind its for a pro to interpreted. http://rechargeac.com/how-to/ac-system-pressure-chart

[BAH2SS]

Originally Posted by Black_SS10

You said in your original post you weren't sure if the system was properly charged or not. The pressures won't matter if the system isn't filled properly. Also, the ambient temperature will affect the pressures. In order to properly measure the running pressures, an AC manifold gauge set needs to be hooked up to the low and high side. Both sides need to be checked. I would rule out low refrigerant by doing an evac and recharge with the proper amount.

Guess i'll have to buy those cans which comes with a pressure gauge on top of them because they have a specific amount of freon in them. the way they do it around here is they hook up the gauge to both sides and vacuum the system for few minutes then recharge based on the pressure reading.

Originally Posted by PowertoLove

Look at this chart but keep in mind its for a pro to interpreted. http://rechargeac.com/how-to/ac-system-pressure-chart

Thanks a lot, much appreciated.

[gtstorey]

They need to vacuum more than a few minutes if the system has been apart or completely discharged for any length of time to get the moisture out. And then there is no reason to not put the new charge in by weight. Or the old way of adding freon slowly until the temperature no longer drops. Of course neither one of these methods trouble shoot other problems in the system.

[silversleeper]

I miss the days of the sight glass on the dryer. There was a canister with a small glass window on top the size of a dime. If it was very low on freon only gas was in there and it was clear. If it was full then you saw clear also and hard to tell if it was very low or full because all liquid behind glass is clear. But if it was full it was working usually so you knew if it was full or empty. The good thing was, you simply added freon until bubbles stopped passing by the window. No gauges or hassles.

[PowertoLove]

I like the orifice tube systems, these expansion valve systems are weak at best. The expansion valve is old old 80 year old tech in a 20 something car.............weak is all I can say. The only reason they could have for not using a orifice tube is to generate lots and lots of dealer service work. No way to swap it either unless you want to make custom parts, just not worth it. the system is also TINY. It has no reserves, if anything is a little off it won't be ice cold like the older systems. I had to tweak mine because it just wouldn't get cold enough on a 90 degree day. The amount of refrigerant I removed was very little, oz or so but instantly it was ice cold compared to just cool. When systems are this touchy most will not be setup properly.

I'll tell ya what really twists my brain cells on these cars is the poorly designed fuel systems. This direct injection is so far from what it should be its stupid. I really want to get away from it, Maintenance nightmare. All the dealers I called had different services and they were all 350-500 dollars. Recommended every 18-25k miles! GM you and the entire industry are a joke! My grandmother could come up with a better system AND SHES DEAD FOR 40 YEARS!

[Tajefe Couple]

Originally Posted by PowertoLove

I like the orifice tube systems, these expansion valve systems are weak at best. The expansion valve is old old 80 year old tech in a 20 something car.............weak is all I can say. The only reason they could have for not using a orifice tube is to generate lots and lots of dealer service work. No way to swap it either unless you want to make custom parts, just not worth it. the system is also TINY. It has no reserves, if anything is a little off it won't be ice cold like the older systems. I had to tweak mine because it just wouldn't get cold enough on a 90 degree day. The amount of refrigerant I removed was very little, oz or so but instantly it was ice cold compared to just cool. When systems are this touchy most will not be setup properly.

I'll tell ya what really twists my brain cells on these cars is the poorly designed fuel systems. This direct injection is so far from what it should be its stupid. I really want to get away from it, Maintenance nightmare. All the dealers I called had different services and they were all 350-500 dollars. Recommended every 18-25k miles! GM you and the entire industry are a joke! My grandmother could come up with a better system AND SHES DEAD FOR 40 YEARS!

Totally agree! We looked at my system this last weekend and decided probably an expansion valve(these are terrible) issue since pressure gauge went to retard when compressor kicked back on. When I got to buddies house AC compressor wasn't running and pressure looked okay.Shut the car off for 10 minutes then started AC compressor kicked on and got cold but gauge reading was off the chart. He recommended replacing the dryer and condenser while doing the expansion valve to avoid any problems with future line blockage. Maybe should just try an expansion valve but would hate to ruin one since they cost around $80 for the Camaro?

Side note my friends a master mechanic helping me so he's not getting paid anymore for the extra work but GM is banking on parts!

[Tajefe Couple]

Maybe this will help you, exert from 2010 shop manual.

Can download the shop manual from Blake here post #105
https://www.camaro5.com/forums/showt...t=19184&page=8

[PowertoLove]

If the expansion valve is not working you would see high pressure on the high side and lower than normal pressure on the low side. If you look at the chart I posted above it should look very close to that info. Another test if you can at it on these Camaros is check the inlet and outlet temp on the evaporator. Both should be very cold and very close to same temp.

If the high side pressure is high and the low pressure side is too low AND the evap inlet is cold and the outlet warm most likey the expansion valve is stuck closed and needs replacement. I really hate expansion valve systems in cars, constant troubles.

[Tajefe Couple]

Originally Posted by PowertoLove

If the expansion valve is not working you would see high pressure on the high side and lower than normal pressure on the low side. If you look at the chart I posted above it should look very close to that info. Another test if you can at it on these Camaros is check the inlet and outlet temp on the evaporator. Both should be very cold and very close to same temp.

If the high side pressure is high and the low pressure side is too low AND the evap inlet is cold and the outlet warm most likey the expansion valve is stuck closed and needs replacement. I really hate expansion valve systems in cars, constant troubles.

My problem is an intermittent one, but yes high pressure pegged the gauge. Don't think low side dipped much(not certain as he read the gauges). Inlet was cold and outlet was warm enough couldn't touch it without a rag. So thinking it's probably the expansion valve. He just recommended if replacing expansion valve that normally should replace the dryer, but left it up to me. Said it would be to make sure if any debris was in the line it wouldn't eventually cause the same problem and clog the expansion valve again. He also said should be able to tell if other issues exist like failing compressor if there is metal found. He to expressed how horrible the expansion valves are. Just glad it acted up and did both work and not while at his house.
Thanks for the advice!