R-134a Recharge Questions

Greetings
I am looking for information on materials and procedures. I will be working on two '95 Grand AM's. One seems to be working ok but after measuring the
high and low sides with a pressure gage it shows that it is low on refrigerant. The other had the condenser removed because of collision damage. I plugged the ends with ear plugs right away but there is evidence that it had been worked on before.
First, there several different kinds of refrigerant available. Some is just straight 134, some has dye in it. some has stop leak in it and some has oil in it. The last one that I looked at was made by EF Products It says Quest at the top of the can. It says that it contains synthetic "A/C booster" plus "Stop Leak". It claims to make air colder. It says that it adds lubricant also.
Any recommendations on what type to use?
When Filling the car that is working, should I put the gage on the high pressure side and add refrigerant until the gage is in the pressure range for the ambient temperature? Is there anything else that I should do?
On the car that had the condenser removed, I will apply a vacuum to the low pressure side for several hours then fill. (One thing that I don't understand is how a vacuum on a pressure system will accurately check for leaks. Wouldn't the vacuum pull openings together and pressure open them up again?) I am thinking about taking a chance that the dryer is ok. If I am wrong what will happen? How do I know if there is enough oil in the system? The factory manual says to use a 525 viscosity oil but the store sells it in low, medium and high viscosity.
Thanks Scott
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"" wrote: > Greetings > > I am looking for information on materials and procedures. I > will be working > on two '95 Grand AM's. One seems to be working ok but after > measuring the > high and low sides with a pressure gage it shows that it is > low on > refrigerant. The other had the condenser removed because of > collision > damage. I plugged the ends with ear plugs right away but there > is evidence > that it had been worked on before. > > First, there several different kinds of refrigerant available. > Some is just > straight 134, some has dye in it. some has stop leak in it and > some has oil > in it. The last one that I looked at was made by EF Products > It says Quest > at the top of the can. It says that it contains synthetic "A/C > booster" plus > "Stop Leak". It claims to make air colder. It says that it > adds lubricant > also. > > Any recommendations on what type to use? > > > When Filling the car that is working, should I put the gage on > the high > pressure side and add refrigerant until the gage is in the > pressure range > for the ambient temperature? Is there anything else that I > should do? > > On the car that had the condenser removed, I will apply a > vacuum to the low > pressure side for several hours then fill. (One thing that I > don't > understand is how a vacuum on a pressure system will > accurately check for > leaks. Wouldn't the vacuum pull openings together and > pressure open them up > again?) > I am thinking about taking a chance that the dryer is ok. If I > am wrong what > will happen? > How do I know if there is enough oil in the system? The > factory manual says > to use a 525 viscosity oil but the store sells it in low, > medium and high > viscosity. > > Thanks > Scott
First are you using actual high side/low side gages or just one of those low side red/green gages because pressure can very a lot with tempaure and cooling load as it is far from constant and actaul pressure readings from both sides call tell you actual charge set with tempature is factored in.
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You sound well versed , so here goes. A system that can't hold vacuum, won't hold pressure. When the evac. runs, the guage should read aprox. 10 to 20 inches Mercury [ INHG ] when the air is sucked out, if the guage stays aprox Zero than no meaningful vacuum is being formed, due to air leaking in and replacing it.
All you need to refill is an Ester Based Oil Oil shot and aprox. 3 cans R 134 A An inline dryer, used for commercial AC systems can be sunned, or gently heated, evacuated, and used as a final air dryer for testing evacuated system. { Caution ... Do not use compressed air to test a R134A system, evacuate first ]
Replace Orifice tube and all O rings, tighten snug but gentle, I like Mobil 1 as a prelube. Avoid sealers and dyes.
Here's a tip for someone smart enough to appreciate it. Save junk fittings from bogus AC parts, adapt car AC to standard pipe, now you've got all sorts of cool testing adapters.
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I can't find any mention of an orifice tube in the manual.

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I am using a single 500 PSI gage sold by Interdynamics. I put it on the low side started the engine and watched the reading for a few minutes. I shut off the engine put on the on the adaptor on the high side restarted the engine and watched it for a while.

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YOU are not trained nor qualified to work on AC An AC shop charges VERY LITTLE to charge an AC system PROPERLY A DIY'er does not have the tools nor qualifications to do this.
IF you are repairing a system that has been discharged and you do ALL the necessary wrenching work, and replace ALL the required parts to save on labor costs is one thing. But the recovery , recycling, flushing, evacuation and recharging an AC system is best left to a PRO.
a 10% overcharged AC system operates worse than a 50% undercharged system. Life expectancy of the compressor is cut by over 50% etc.
There are NO quick fix AC boosters either,, just because its sold does not make it work. They sell all kinds of beauty products and your Mother in Law still looks like the Hulk.

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says
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"Im Right" wrote:

does
THis is not really true. It is not rock science to work on one and anyone that can follow instructions and has the right tools and gages can do it. A good set of gages is key here. ALso a 10% overcharge will not cool less than a 50% undercharge and usually it will cool about the same as a normal charge though pressure will start to climb a bit. Also the statement about a much shorter life with aslight over charge vs 50% undercharge is bull too because with a 50% under charge your compressor can have a VERY short life because the return freon COOLS and LUBRICATES the compressor and with a 50% charge the compressor will run very hot internally. It takes a lot more than a 10% over charge to noticeble degrade a system and to shorten its life as well from increased head preasure. And finailly there is not need to flush the system 99% of the time but you do need to evacuate it (vacum it) when the system has been opened or you change freon types. I have been working on car and house A/C systems for 30 years and never been to school for it but I can read and learn as I did 30 years ago. I do not do it for hire just my own needs and a few freinds and I am very picky about it being right too (a lot more than some techs I have seen do it)
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SnoMan
I was hoping to hear from you. It sounds like that you have some experience with AC. Does your name have anything to do with that?
Any how, I have a vacuum pump that will draw 28.5 in hg of vacuum. This will evacuate the system properly.
What I really want is input on refrigerant selection. Should straight R-134a or one of the blends with synthetic "A/C Booster"? What about the ones that have stop leak? How do I know if I need to add oil and how much?
Is it best to monitor the low side pressure while filling or the high side? With my tools it is easier to monitor the high side.
Thanks, Scott

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A DIY'er does not have the tools nor qualifications to do this.
Thats funny, I have been charging my own AC systems for the past 7 years with guages from Walmart and it always cools excellent.

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......has the right tools and gauges and training.......
it is a rather LARGE investment to buy a $2000 recovery/ recycle machine $400 vacuum pump $200 Gauges $500 charging cylinder $300 30 LB cylinder of R134a
All that to save a $29 charge plus the freon, at a shop who does it for a living

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It is more like this: Make an appointment. Take time off work. Stand around until they get to you. Arrange for a ride back to work. Wait around for call back with an estimate. Agree to their price. Arrange for a ride back to the shop. Stand around until they get to you. Pay out $150-$200. Pick up the car which now has new scratches on the fender and grease stains on the seats. Hopefully they did it right and I'll not have to go back.
Since the system is empty I have no need for recovery equipment. I have about $65 into gages and valves. Borrowed a pump. Don't need 30# of refrigerant (Freon is a trade name). Cans cost about $13 per pound.
You must do A/C for a living. I can see where you want to save your industry. Let me know where your shop is and I'll bring it by and let you do it for $29 +.

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actually quick-lube places do it also. They charge about $30 plus the R134a You are in and out in 30 minutes, most are open from 6a to 8p for your convenience.

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same here for at least 20 years to the OP while your there have a look at hydrcarbon cooling i have been using r12a (iso-butane propane mix i think) for a couple years now a lot easier to charge than the propane i was using before that and works much better
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propane/butane, bad plug wires, leaking hose at 300psi,,,, sounds rather smart

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"Im Right" wrote:

No more or less smart than a leaking fuel line plus you have only maybe a 32 oz of hydrocarbon ES12 verse 20 to 30 gallons or gas. When My r12 supply is gone I plan to use the ES 12 stuff myself because I have read good things about it and it work even better than R12 in a R12 system and a LOT better than R134 in a R12 system and is fully compatable with R12 oil which R134 is not.
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