Adding AC Refrigerant
05-26-2002, 10:12 AM
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Adding AC Refrigerant
I think i need to gas up my ac, i'm hoping i don't need a compressor or some other expensive part, It only gets cold when it's cold outside, it will take hrs to get cold if it is hot. Does anyone know what kind of ac we got, is it the r135 or something, can i buy that thing in the can from the atuo parts store to charge the ac up, if so, is there a special way to do this?
Thanx
Thanx
05-26-2002, 01:58 PM
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It is the newer R135 but there is a reason it is leaking out. If you simply put more in it will just leak out again. Sometimes the leak is very obvious because of the build up of oily dirt around the leak. More frequently you need a halogen detector to trace it down. Some mechanics inject a flourescent dye into the system then use a black light to look for the flourescing area around the leak. This only works in open areas and is less than usefull for something like a leaking evaporator that is well hidden. However, it is my opinion that a well trained A/C mechanic should be able to locate it with either an electronic or flame halogen detector.
Once you find and fix the leak you will proabably have to discharge the entire system to fix it. In that case, before it is recharged, it has to evacuated with a vacuum pump after replacing the receiver/dryer. You also have to make sure that you did not loose an excessive amount of compressor oil through the leak or when the system was intentionally discharged.
If only a small amount leaked out then just adding a little new refrigerant is all that is needed until it leaks again. If the leak is very large then there might be air and moisture in the system and you will certainly have to evacuate it with a vacuum pump first. In either case you will need a guage set set to determine how much new refrigerant to add. A sight glass can help guide this but I think I remember that sight glasses are no longer being supplied. You also have to know how to add new refrigereant to 100% avoid introducing any air or moisture into the system. It is very difficult to do this when using the cheap little hoses that come with some cans. The manifold (part of a guage set) is very useful to do this right.
A likely source of the leak is one or more microscopic pinholes in the evaporator. Taking the dash apart to get to to the evaporator is definetely not for the feignt hearted. I have done this more times than I care to remember but next time I am going to pay somebody I trust to do it for me. It is just too much work with too great an oppurtunity to loose a part or not remember where everything goes when reassembling the damn thing.
In other words, you need to know what you are doing and have specialized tools to fix an A/C. There is also a saftey concern because of the extrememly high high side pressures used with R135 systems. You can try adding some cans but it will probably not result in a fix that lasts for any length of time. Also, if the eveaporator is not now leaking, and there is any moisture at all in the system as a result of the leak or your replacement efforts, it will eventually leak (this is a certainty). An evaporator is $400 - 500$ just for the part.
Once you find and fix the leak you will proabably have to discharge the entire system to fix it. In that case, before it is recharged, it has to evacuated with a vacuum pump after replacing the receiver/dryer. You also have to make sure that you did not loose an excessive amount of compressor oil through the leak or when the system was intentionally discharged.
If only a small amount leaked out then just adding a little new refrigerant is all that is needed until it leaks again. If the leak is very large then there might be air and moisture in the system and you will certainly have to evacuate it with a vacuum pump first. In either case you will need a guage set set to determine how much new refrigerant to add. A sight glass can help guide this but I think I remember that sight glasses are no longer being supplied. You also have to know how to add new refrigereant to 100% avoid introducing any air or moisture into the system. It is very difficult to do this when using the cheap little hoses that come with some cans. The manifold (part of a guage set) is very useful to do this right.
A likely source of the leak is one or more microscopic pinholes in the evaporator. Taking the dash apart to get to to the evaporator is definetely not for the feignt hearted. I have done this more times than I care to remember but next time I am going to pay somebody I trust to do it for me. It is just too much work with too great an oppurtunity to loose a part or not remember where everything goes when reassembling the damn thing.
In other words, you need to know what you are doing and have specialized tools to fix an A/C. There is also a saftey concern because of the extrememly high high side pressures used with R135 systems. You can try adding some cans but it will probably not result in a fix that lasts for any length of time. Also, if the eveaporator is not now leaking, and there is any moisture at all in the system as a result of the leak or your replacement efforts, it will eventually leak (this is a certainty). An evaporator is $400 - 500$ just for the part.
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