JD 4840 A/C

[Howard H.]

I have had a new old-stock JD A/C compressor out in the barn for years and went to put it on my JD 4840 today (the one that is on the tractor is locked up), and realized it is labeled as for R-12.

The A/C system on my 4840 is R134a.

Will the new old-stock compressor work even though the rest of the system was converted to R134a years ago?

I'm not sure if a "compressor is a compressor" and it would work fine as a direct replacement or if there are truly internal differences in the two units.


Thanks for any advice,
Howard

 

[Roger in Iowa]

Compressor will have mineral oil. Not compatible with R134. May empty oil somehow and put oil in for R134. Don't have experience doing it.

 

[joeysmith]

Probably be a good idea to drain the oil an put pag oil in it but yea should work fine

 

[used red MN]

I have had a new old-stock JD A/C compressor out in the barn for years and went to put it on my JD 4840 today (the one that is on the tractor is locked up), and realized it is labeled as for R-12.

The A/C system on my 4840 is R134a.

Will the new old-stock compressor work even though the rest of the system was converted to R134a years ago?

I'm not sure if a "compressor is a compressor" and it would work fine as a direct replacement or if there are truly internal differences in the two units.


Thanks for any advice,
Howard

Assuming you have the original compressor that came on the tractor it is a GM/Harrison A-6.
Here is how to drain the oil. You can see the drain plug stick off the bottom in the photo.

To drain oil from a classic GM A6 compressor, remove the oil drain/sump plug located on the bottom belly or side of the compressor body. Rotate the clutch plate by hand and tilt the heavy unit toward the ports and plug hole to completely empty the old fluid into a calibrated measuring container.
Draining Procedure

• Locate the plug: Find the drain/sump plug on the bottom or side of the heavy cast-iron/aluminum housing.
• 
  
• Remove the plug: Carefully unthread the plug.
• 
  
• Drain and tilt: Tip the compressor in multiple directions and rock the clutch back and forth to purge oil trapped in the internal pistons and sump.
• 
  
• Measure output: Record the exact fluid amount drained to gauge what the system previously held.

Hopefully you know the system should be evacuated 2-3 hours with a vacuum pump once the compressor is installed.