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Air Conditioning Recharge ? With Orifice

bac078

By bac078
in Ask A GM Technician

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bac078 Enthusiast

bac078

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I have a 2005 GMC Sierra Crew Cab that has the orifice with the high and low pressure for the air conditioning. My question is... Is this something that I can recharge myself as a DIY'er, or do I have to bring my truck in to get a mechanic to do. I can figure out which one is the Low pressure side, So can I just hook up the pressure guage, then go to town with the R-134a. I am not familiar with the orifice setup, so I am looking for some advice.

Lahey99 Enthusiast

Lahey99

Posted
Posted
I have a 2005 GMC Sierra Crew Cab that has the orifice with the high and low pressure for the air conditioning. My question is... Is this something that I can recharge myself as a DIY'er, or do I have to bring my truck in to get a mechanic to do. I can figure out which one is the Low pressure side, So can I just hook up the pressure guage, then go to town with the R-134a. I am not familiar with the orifice setup, so I am looking for some advice.

 

 

I'M not a hm mechanic but a refrigeration mechanic and I advise anyone to stay away from it id tpi are not to sure what to do, and under charging or over charging could cause issues as well

Just my 2 cents though!

Doug_Scott Senior Enthusiast

Doug_Scott

Posted
Posted
I have a 2005 GMC Sierra Crew Cab that has the orifice with the high and low pressure for the air conditioning. My question is... Is this something that I can recharge myself as a DIY'er, or do I have to bring my truck in to get a mechanic to do. I can figure out which one is the Low pressure side, So can I just hook up the pressure guage, then go to town with the R-134a. I am not familiar with the orifice setup, so I am looking for some advice.

 

Refrigerant goes in by weight. Unless the system is empty, you really have no sure way of telling how much is in there. Since you are asking, I have to assume you really do not know a whole lot about it, so trying to add based on how the pressures behave is best left to someone that understands the system. Some of the logic of an a/c system is odd, for example you would think that a system with low pressure on both sides must be low on refrigerant, when it is most likely a plugged fixed orifice tube. Leave it to the pro unless you know what you are doing.

bac078 Enthusiast

bac078

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You are right, I dont know a whole lot about this. I have done work on my wifes pathfinder, but that was not an orifice system. It was relatively simple, I could tell there was a leak... and I measured based on pressure and then filled to the appropriate pressure based on ambient temperature. Since this is an orifice system I was unsure if it was as simple as the pathfinder was. Of course I know someone will chime in... you had a leak and you didnt trace down that problem and fix it.. I used the R-134a with a stop leak additive and haven't had issues in over 18 months. So I was hoping my GMC was the same so I dont have to pay a pro and do it myself... But the advice here says I shouldnt touch it... Bummer for me.

Doug_Scott Senior Enthusiast

Doug_Scott

Posted
Posted
You are right, I dont know a whole lot about this. I have done work on my wifes pathfinder, but that was not an orifice system. It was relatively simple, I could tell there was a leak... and I measured based on pressure and then filled to the appropriate pressure based on ambient temperature. Since this is an orifice system I was unsure if it was as simple as the pathfinder was. Of course I know someone will chime in... you had a leak and you didnt trace down that problem and fix it.. I used the R-134a with a stop leak additive and haven't had issues in over 18 months. So I was hoping my GMC was the same so I dont have to pay a pro and do it myself... But the advice here says I shouldnt touch it... Bummer for me.

 

It does not matter what type the system is. When it is not running, it is all the same. Problem with using ambiant temp method is you can get proper pressures on either side of the optimal fill weight. In other words, you can be under or over filled, and still show the proper pressures. It is also hard to fill the system when it is not running. The can you fill from will be ambient temp, so will have the same pressure as your static system. You need to have the low side running to get it to get refrigerant to flow in.

 

Even when it is running, the low side should be in the same range regardless of what type of system it is (assuming it is using 134a).

 

I have been out of the mechanic trade for about 20 years, but did a/c, front end, alignment and tune up before being hurt. I never did get to work with R134a.

minibike132 Senior Enthusiast

minibike132

Posted
Posted
I used the R-134a with a stop leak additive and haven't had issues in over 18 months.

 

 

I'm with what everone else said but I would like to add, it is a horrible idea to use stop leak. I know you used it and have not had an issue and many do. However if you do end up having an issue it will be catastrophic to the point that everything will need replacing. Leave it in the vehicle that has it in it but don't use it on another. Trying to remove it at a shop will ruin the equipment, just opening the system will ruin your system.

 

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