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Discussion Starter #1
Hey y'all: A mechanic replaced my AC compressor (my second in this vehicle) and drier with an Autozone over a year ago and MAN! It was colder than I have ever felt in this car. About a year later that compressor died (froze) and Autozone warranty replaced it and I paid the same mechanic to install it. When I reported that the system was not nearly as cold as with the old compressor, the mechanic said come back next summer (it was fall) and he'd take a look. Well, he is seldom seen and hard to find. So I took the car to Firestone for the $9.99 AC checkup special. They reported pulling a vac, adding dye, and not finding any problem other than needing 2 lbs. and 2 oz. of refrigerant for $165! I told them no thanks and decided to add the refrigerant myself.

Do you think that it is okay to just add the 2lbs. and 2ozs to the system based on Firestone's
measurements? I have one of the dual gauge setups. Thanks much--
 

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You should add refrigerant while watching both low and high side pressures, and stop adding when high and low side pressures are correct for the ambient temp. The only time I fill a system based on refrigerant weight is if the system was opened and all refrigerant is gone, such as after replacing O rings, compressor, etc. Of course, I evacuate the system for at least a half hour to an hour before refilling.

I have no clue how someone could say that exactly 2lbs and 2 oz were needed.
 

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I seem to remember these systems take 1000 grams of refrigerant which is 2 lbs 3 oz. So they are charging for a full refill of system. That's how they can tell, just not right.

Is the system working at all and how long is the compressor clutch engaged? If it engages for a few seconds then the system needs less that the stated amount, maybe 12 oz. Total system takes three cans almost exactly.

A system can be also filled based on superheat method which says the inlet temp of evaporator should be the same as the outlet. That means that the evaporator is full of liquid refrigerant to absorb heat.



I also had a problem with the blend door actuator which which was adding 17 degrees of heat because it failed.
 

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Discussion Starter #4
I wish that I had told Firestone to leave the system evacuated. The blend door was recently checked. It is cooling slightly, as it was when I took it for diagnosing. They said they returned the refrigerant to the system and added dye. Does that mean that it is ready for adding refrigerant without the need for another evacuation? Thanks for your help.
 

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I wish that I had told Firestone to leave the system evacuated. The blend door was recently checked. It is cooling slightly, as it was when I took it for diagnosing. They said they returned the refrigerant to the system and added dye. Does that mean that it is ready for adding refrigerant without the need for another evacuation? Thanks for your help.

Should be, but you can trace down the system to see if there is any oily spots or dye showing. Usually service valves are a primary source of leaks. I usually charge it until the compressor stays continuously engaged on a hot day. Danger of doing it that way is that if you have a weak compressor or a plug orifice you can overcharge the system. It is funny how they diagnosed they system. They recovered the refrigerant to check for leaks. I would think they would use pressures to check system and then inject dye to find leaks. It can be added without fooling with refrigerant with a special injector that a shop should have.
 

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Discussion Starter #6
Well, I got the manifold kit and refrigerant ready and the low pressure valve is missing the threaded connector (see pic attached). I remember that the leaky valve was replaced last year with the compressor. Can you tell what's wrong/missing? It seems that if it was this way when Firestone received it they would have mentioned it. No?
 

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^+1 with Scott. Hi service port pictured. Lo port straight back near the firewall. Get cap(s) next time you're at a pick 'n pull jy.
 

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Discussion Starter #9
As I remember, the manifold line screws into the port. There are no threads there to screw the manifold line. Also, the pictured port is much larger than the manifold line and does not fit.
 

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134a connectors are quick release and have internal threads for the service caps. Caps screw on. They make the connectors different sizes to protect people who try to connect cans to the wrong point connecting a can to high side while compressor is working can explode can thus the different size connectors.
 

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It's not cooling well because you did not replace the accumulator. That needs to be replace every time you open the system. And it the event of a compressor failure, you should replace the condenser as well.
 

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I am a certified A/C technician and will offer some advice: Many people come to me AFTER they have wasted money on repairs that have been done by incompetent shops or DIY. The results are often catastrophic; requiring parts and labor beyond what the car is worth. Example: A/C Pro in a can! Now everyone is an A/C Pro! Put in a couple cans and you will probably have cold air for a short while, but soon you will need a compressor, condenser, orfice, reciever/ dryer and complete system flush. The auto stores love it. Find an ASE Certified A/C shop nearby.
 

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Your car takes 34 ounces of refrigerant. Use a postal scale to measure how much you put in. Charging using pressures and temperature is an indirect measurement and can be affected by the health of other things in the system. Weighing is the only direct way to tell if you have the right charge.
Did you get a reman compressor? That's real hit or miss. It could have been worn when you got it from AZ. Bad overhaul shops will often just clean it up and put a coat of paint on it and resell it. Seriously.
Summit Racing has new ones for less than $150.

rsteve speaks the truth. If you don't know much about air conditioning, have someone competent do it.
 

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My understanding also is that the correct way to add refrigerant is by weight. The label under the hood tells you how much the system is designed to use. Of course you have to start with an empty system for that to work... Years back I replaced a failing compressor in my sable. Replaced the drier, condenser and expansion valve and recharged the system with the specified weight of refrigerant. Friend who used to work in HVAC lent me his vacuum pump, r134 tank and scales. It's worked great ever since. Anytime you open the system I would definitely replace the drier and the expansion valve, at a minimum. My expansion valve had quite a bit of debris in the screen, and that was on a compressor that had not yet grenaded (just made a lot of noise).
 
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