how much R134a does it take to....

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If the system capacity is 24 oz, how many oz does it take so the low pressure sensor will allow the compressor to cycle? I realize it will not cool the vehicle. I am thinking 4 to 6 oz. But just a guess.
 
You don't have enough info to calculate.

You need to know the volume of the system, not just the operating fill weight.

R134a expands about 200 times from liquid to gas. To get the compressor to cycle the system needs to be full of gas, with just a trace of liquid.

A typical automotive system needs just an once or two to active the low pressure switch, but the cycle will be very fast.
 
It doesn't really work that way. The system capacity does not tell you the volume of the system or the temperature. The smaller the volume and the higher the temperature, the less you'll need. It's summer right now so the easy answer is "not much."
 
Originally Posted By: djb
To get the compressor to cycle the system needs to be full of gas, with just a trace of liquid.

A typical automotive system needs just an once or two to active the low pressure switch, but the cycle will be very fast.


Yep
 
Are you feeding from a real bottle with real gauges or one of those garbage walmart cans that let in as much air as refrigerant?

I hope that if you have a leak, you're following the law and fixing it properly before charging.

Doing it right, with gauges, will tell you that there is a static pressure that varies by temperature, that will indicate a two phase system. The low pressure switch will likely be much lower than that pressure in the summer time, likely by a factor of three. So I'd just let the gas pressure rise off a bottle and it will trip the switch.

But again, if you lost the refrigerant not through a proper recovery process, you should pressurize with nitrogen and a trace of refrigerant, sniff it and find the leak, fix it, recheck, the. Pull vacuum and refill properly.
 
I have a set of real gauges and a can tapper for the R134a. In my case its leaking out over the winter to the point next spring/summer, the compressor will cycle, but no cooling. I have added 12 oz. I am thinking I need another 8-10 oz.

Trying to delay getting it properly fixed. Up in the air if I want to buy the leak detector and recovery pump/tank.
 
Originally Posted By: Donald
I have a set of real gauges and a can tapper for the R134a. In my case its leaking out over the winter to the point next spring/summer, the compressor will cycle, but no cooling. I have added 12 oz. I am thinking I need another 8-10 oz.


I also think you need to add more r134a. Just go ahead and do it.
 
Originally Posted By: LT4 Vette
I've used the Walmart 'artic freeze' cans and it made my A/C very cold.

$25 is better than spending money at repair shop.



It might be in the short run, however, if you ever need your A/C properly serviced by a shop they will NOT work on it because they will destroy their refrigerant recovery machine due to the sealers used in that product.
 
I thought AC shops with good equipment, filter out any sealers and some leak detection dyes. I also helped my son recharge his system with a "garbage" system from Adv Auto. The AC works very nice-thank you. Ed
 
It used to be that the sealers turned into some hard block seal stuff overtime but lately I've heard it is basically just a seal swelling oil charge.

I just did someone's today using the right equipment but man some of those plastic nozzles suck.

FYI Autozone will rent out the manifold gauges & vacuum pump. It is just pricey even if you get all the money back.
 
If you have to add that much refrigerant then the system must be near empty. It's rare when a small "leak" causes all of the refrigerant to leak out.....sounds like it's time for a leak repair.

Chrysler products often suffer from leaking evaporators....in my case, I've replaced the evap in my '96 Dakota and our daughters 200? Jeep. Prior to the replacements, both were good for a recharge every 6 weeks or so. I did the Dakota in 2008 and haven't touched it since. The Jeep was done in '12 and so far so good.
 
FWIW I just added freon to my Challenger yesterday with a $40 kit from Auto Zone called "A/C Pro. It has a gauge on it and you calibrate it to the ambient temp. I was having a problem with it not blowing cold enough. According to the gauge, it was in the green zone, but low. I added about 2/3 of the can that came with the kit and now I have cold A/C.
 
unfortunately that low side gauge on the ac pro can does not mean anything. high side pressures are needed.you could do just as well by feeling the suction line whie charging.
 
Originally Posted By: Eddie
I thought AC shops with good equipment, filter out any sealers and some leak detection dyes. I also helped my son recharge his system with a "garbage" system from Adv Auto. The AC works very nice-thank you. Ed
yes we do. and the customers help me pay for the filters.its all added into my price
 
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