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Low is 28, high is 215. Sight glass in the dryer is milky white. Blows ambient temp from blowers.

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So the sight glass is not part of the new dryer? Is it hard to replace the sight glass? You really need to be able to see what is going on with the refrigerant flow.
What was your ambient temp when you checked the pressures? I do not know your tractor as well as others here do but they seem just a little low to me, especially if you are at the correct Freon weight.
Check the heater hoses. Something is not adding up here.
 

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Your head pressure seams a little higher then it should be and your suction side seams low. Which leads me to think you have some type of restriction in the system. Also you sight glass should not be milky looking it should be clear. I would think your compressor is ok as it seams to be pumping. With a milky sight glass and pressures you have I’m thinking some type of contamination or moisture which could have caused TXV or filter restriction.
 

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So the sight glass is not part of the new dryer?
Sight glass is incorporated in dryer. I think John meant the fluid inside sight glass is "milky looking" which could be moisture in system. Blowing out AC components with compressed air can introduce moisture to system. I wonder if "new dryer was installed" when compressed air was utilized.
 

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Discussion Starter · #24 ·
New compressor installed, vacuum pulled to 28 for 2 hours. Charged with 56 ounces of refrigerant. Gauges and temp from vents attached. Tractor at about 1900 RPM. Ambient temp 80.


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How did you measure 56 ozs? Do you have a refrigerant scales? I still think 56 ozs is too much 134A for a SGB AC system.
 

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Discussion Starter · #26 ·
I used 4 12 oz cans, weighed 4 empty cans average 3.13 oz, then added 8 oz from another can. Used an electronic food scale. Dealer said 3.6 lbs which equals 57.6 oz. I stopped at 48 oz (4 cans) just to check the temp from the vents. That is as good as I can do with my equipment and frankly it is better than my mechanics did.

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Sounds as if you measured the best you can with what's available to you. It's odd that the JD 4255 tech manual clearly states 4#s of R12 & 134A would only require 80%of that amount
 

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It was mentioned but I will ask, did you check the heater hoses temperature? Even though the heater valve is off it might be bypassing. Make sure the heater hoses are not warmer than ambient.
Make sure the condenser is clean.
With the pressures you show you should get some cooling.
Make sure the evaporator is not freezing up. It can if it is matted over with years of dust/dirt/chaff. Clean it so you can see through it with a light.
Cab recirculating filter (sponge looking one) clean? Cab drain lines open? Normal to drip condensate (water). Blow up from bottom with blow gun to open.
Its been a while so just thinking back to different scenarios I’ve encountered in a previous life.
Hope you cool down soon.
 

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New compressor installed, vacuum pulled to 28 for 2 hours. Charged with 56 ounces of refrigerant. Gauges and temp from vents attached. Tractor at about 1900 RPM. Ambient temp 80.


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How is it working now?
 

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Discussion Starter · #32 ·
I have not started it for several days. I will open the roof and check the heater core next. Probably put in a new heater temp valve, because the knob is broken off of this one. I do not plan on using the heater but it may as well work, just in case.

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If I didn't plan on utilizing heater If it was my tractor I'd forego the factory valve & install heater hose manual control valve. My JD 4255 has had a manual heater hose shutoff valve since 1994 & has remained closed. Back when I plowed in the Winter I would need the AC on low but no need for heater in N Texas weather.
 

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Discussion Starter · #34 ·
If I didn't plan on utilizing heater If it was my tractor I'd forego the factory valve & install heater hose manual control valve. My JD 4255 has had a manual heater hose shutoff valve since 1994 & has remained closed. Back when I plowed in the Winter I would need the AC on low but no need for heater in N Texas weather.
Me either in SE Kansas. Any place easier to put a valve? You just use a steel ball valve?

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I always just cut the hose at right rear lower corner post and reroute it to the return line takes like 2 minutes and is completely free. That is unless I am splitting the tractor then I remove the lines and plug them off at block.
 

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I suppose if you never need heat then looping the hoses or plugging them will work. UP here its currently 46 degrees so its heater weather and by noon it'll be 72 and AC weather.
 

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We got a few problems in south Alabama but cold ain't one of them. I have never in my life needed a heater on a tractor I do remember when I was a kid my dad and grandfather had "winter cabs" they would put on there big plow tractors when they still bottom plowed everything in February. But all that was just a windshield and duct to move hot motor air around them.
 

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Discussion Starter · #40 ·
Cut hose in an easily assessible area & install the cutoff in photo below. Easy Peasy.
I see terrible reviews on this valve, think I will look for a ball valve at my local hardware store next time I am in. Thanks for the advice though
 
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