4250 AC question

Eric in KY · May 27, 2016

Hi guys, I got a question on my tractor's AC. Tractor has around 5500 hours and still has original AC unit with R12 freon. My low pressure indicator light started coming on a few days ago. I could turn the AC off, wait a few seconds and turn it back on and the air would be cold. I talked to my buddy about it and he said it was low on freon. He came over and vacuumed out the system. Waited 30 min and the pressure held. He put 3.5 lbs of R134 back in it plus a can of oil. The indicator needle is barely in the blue on the can gauge. I'm still getting the same results. Any thoughts???

This spring I changed radiator anti-freeze, cleaned condenser in front of radiator and cleaned condenser under roof. Neither condenser was very dirty.

Thanks.

88 Diesel · May 28, 2016

Did you change the receiver drier or thermal expansion valve when you converted to 134a, also what type of
oil did he add?

tim s · May 28, 2016

The dryer should have been changed, but the problem is probably the low pressure switch up on top of the cab it is screwed to the line and you can change it with out loosing the charge there is a schrader valve there to help with the change..swap that out and I bet it fixes it.

Eric in KY · May 28, 2016

My buddy suggested not changing the dryer since we were basically mixing the 12 with the 134 oil, even we tried to pump it all out. The system is 33 years old so we thought we'd take a chance on this working. The oil additive was around 5 oz and was a compresser lubricant for 134. We'll change that switch and see if it solves. Is there a way to test the switch?

DONMYEIL · May 30, 2016

I think you need more Freon. You want abt. 85% of the 4 lb. system . Remember a pound is 16 oz. not "3"- 12 oz. cans. And yes the expansion valve , dryer , and system flush would make a more satisfactory change over . I did a lot of them and your way is minimum at best .

newgenjdcollector · May 30, 2016

I am glad my 4250 is still chugging along with R12 in it. Added a couple cans about 2 years ago and it will give you the chills. Could be me, but it seems like the 134A systems just aren't as good.

Eric in KY · May 30, 2016

(quoted from post at 15:33:45 05/30/16) I think you need more Freon. You want abt. 85% of the 4 lb. system . Remember a pound is 16 oz. not "3"- 12 oz. cans. And yes the expansion valve , dryer , and system flush would make a more satisfactory change over . I did a lot of them and your way is minimum at best .

I added a couple more cans of freon and its solved the problem for now. My buddy thought we should go the minimum route since we were converting 12 to 134. But...if this gets me thru the next month or so, which is the busiest time for me, would you still advise the expansion valve, dryer and flush with the 33 year compressor and hoses?

newgenjdcollector · May 30, 2016

(quoted from post at 19:33:20 05/30/16)

(quoted from post at 15:33:45 05/30/16) I think you need more Freon. You want abt. 85% of the 4 lb. system . Remember a pound is 16 oz. not "3"- 12 oz. cans. And yes the expansion valve , dryer , and system flush would make a more satisfactory change over . I did a lot of them and your way is minimum at best .

Click to expand...

I added a couple more cans of freon and its solved the problem for now. My buddy thought we should go the minimum route since we were converting 12 to 134. But...if this gets me thru the next month or so, which is the busiest time for me, would you still advise the expansion valve, dryer and flush with the 33 year compressor and hoses?

Yes, Yes, And Yes. Hoses as need. Also a new compressor is optinal but I would recommend it since the new style compressors are much better suited for 134 than the old style.

4250 AC question

Eric in KY

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88 Diesel

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tim s

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Eric in KY

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DONMYEIL

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newgenjdcollector

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Eric in KY

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newgenjdcollector

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