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Discussion Starter · #1 ·
I am not an air conditioner guy but my local mechinacs cannot seem to get my 4430 air conditioner right. I put a new Sanden style AC compressor on my 4430 along with expansion valve and dryer. I cannot find anything telling me what the correct charge is. Some say 40 0z and others 56. Seems too be a big difference to me. Also it dropped from 27 to 22 vacum in about 17 hours. Should I chase a leak? Thanks in advance.
 

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Leaks don't get better on there own. I like charging a system based on a known correct amount, but you can charge based on a ambient air temp/ high and low side pressure chart. That is how I have added to a low system that leaks down over years.
 

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On a 4xxx John deere it's usually about 5 cans. I wouldn't worry about that small of a leak my guess is that's only about a can or 2 a year. If you do decide to look for it check the low side line behind the battery and Insulated line going up left rear cab post. Those 2 account for about 90% of leaks i have seen. The exact amount I put in is hard to say I try to have the tractor parked in the shade, running about 1700 rpm, door closed, when low side lines has water beads almost cold enough to freeze it is the best it will do.
 

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I have 4 cans of R134A in my JD 4255 & AC cools fine in Texas heat. My 4255 tech manual states 4#s of R12 so 80 percent of 4#s(64 oz's) of R12= 51.2 oz"s of 134A
 

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Discussion Starter · #6 · (Edited)
Cleaned all lines, condenser, evaporator with carb cleaner, (per my mechanic) blew them all out with shop air. New o rings at all fittings, pulled a vacuum for 1 1/2 hour, let it sit for another 1 1/2 hour, no vacuum loss. Charged with 5 1/2 cans of Freon. Pressures are 35 low, 250 high, sight glass on my dryer is not clear. Vent temp is about 85 at about 1800 RPM. What did I do wrong? Where should I start? Suction line is cool, and sweating but not frosted over. More Freon?
 

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Discussion Starter · #8 ·
Dealer said 3.6 lbs, that should be about 5 1/2 12 ounce cans.

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Cleaned all lines, condenser, evaporator with carb cleaner, (per my mechanic) blew them all out with shop air. New o rings at all fittings, pulled a vacuum for 1 1/2 hour, let it sit for another 1 1/2 hour, no vacuum loss. Charged with 5 1/2 cans of Freon. Pressures are 35 low, 250 high, sight glass on my dryer is not clear. Vent temp is about 85 at about 1800 RPM. What did I do wrong? Where should I start? Suction line is cool, and sweating but not frosted over. More Freon?
85° discharge temperature in the cab? The A/C is doing nothing if that is correct. I am spit balling but I would suspect a compressor issue (again) or the vacuum was not pulled correctly or lost as some point in the process. Did you blow out the lines and individual components when you had them open to replace the o-rings? It should have been done to check for blockages. About the only way to purge when this is done is with nitrogen. Then pull the vacuum. Depending on the ambient temperature the pressures you listed could be a little low, at least on the high side.
I have never tried using carb cleaner. I always use coil cleaner like a residential HVAC guy uses. It will dissolve some of the dirt and debris. I do not think carb cleaner would do that on grass, seed, dirt, and such.
We are talking 134a correct?
 

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Discussion Starter · #10 ·
85° discharge temperature in the cab? The A/C is doing nothing if that is correct. I am spit balling but I would suspect a compressor issue (again) or the vacuum was not pulled correctly or lost as some point in the process. Did you blow out the lines and individual components when you had them open to replace the o-rings? It should have been done to check for blockages. About the only way to purge when this is done is with nitrogen. Then pull the vacuum. Depending on the ambient temperature the pressures you listed could be a little low, at least on the high side.
I have never tried using carb cleaner. I always use coil cleaner like a residential HVAC guy uses. It will dissolve some of the dirt and debris. I do not think carb cleaner would do that on grass, seed, dirt, and such.
We are talking 134a correct?
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My thoughts exactly (AC doing nothing). Yes I cleaned the lines and components when I replaced O rings, no blockage in anything. Ambient temp was 90 - 95. Yes 134a refrigerant. Forgot to mention I installed new temp control and blower switches, just to remove the possibility of them being bad. Like I said I am not an AC guy, but I have paid 2 other mechanics to "fix" it already, figured I couldn't do any worse.
 

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IMHO 5-1/2 cans is too much refrigerant for a 30-55 series JD tractor with SGB. Was your dealer when he stated 3.6#s referring to R12 or 134A? 134A should be 80% fill to R12. Slightly under filled 134A normally cools better than over-filled 134A AC system.
DEFINITELY don't add more refrigerant!!! 3.6#s=57.6 ozs ÷ 12 oz/can= 4.8 cans not 5.5 cans
Have you manually shut off coolant flow in a heater hose? Did you install new receiver/dryer???
 

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Discussion Starter · #13 ·
I noticed this morning that the compressor is sweating. Called Abilene Machine. They are sending a new compressor which will be here tomorrow. Hope it works.

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Before I went to the trouble of R&R the compressor I would lower the 134A charge to correct amount. New compressor that is over charged with 134A isn't going to cool either
 

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Discussion Starter · #15 ·
But why would the compressor sweat? It is not very hot or humid here.

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Discussion Starter · #19 ·
Low is 28, high is 215. Sight glass in the dryer is milky white. Blows ambient temp from blowers.

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I noticed this morning that the compressor is sweating. Called Abilene Machine. They are sending a new compressor which will be here tomorrow. Hope it works.

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Best of luck. For certain check the heater lines. If both are getting hot that is a big part of your problem. Get a cheap and easy in line shutoff to eliminate the possibility.
 
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