MP39 to 134 conversion

[shadygrove]

Recently encountered another old R12 two door box running MP39 that had a compressor less than two years old with a failed compressor.
Granted restaurant equipment can take a severe beating. God knows this one did. Close to a fryer and the kitchen help doesn't monitor box temps.
But it seems that the original R12 systems were able to handle more adverse conditions and survive.
MP39 runs at a higher pressure than R12. The shell temps on some of these compressors run hotter. The amperage is higher.
My supplier has a good price on a mineral oil Tecumseh. Probably because they're not shipping these anymore.
Since I carry POE oil on the truck I'm seriously considering as a test to convert this one to 139. Just measure out the mineral oil and add back POE.
I recently inherited an old grocery store that was all old equipment that was entirely 404 and 139. And I have to admit I like seeing that 139 pressure on the gauge. And that equipment was old and surviving well.
You input is greatly appreciated.

[markettech]

If the unit is cap tube fed I wouldn't consider putting 134A in it.....

[shadygrove]

Thanks..That's the variable that I'm the least comfortable with. I'm planning to use a suction drier to combat any chemical reaction between remnants of mineral oil and AB oil. This particular piece of equipment is a real rat and should be replaced but they can't afford it.

The easiest thing to do would be just go with MP39 but I've been thinking about these blended refrigerants for a couple of years and mulling this over. If the system can somehow approach a clean state (I've thought) then heck, the mfg's are still building with 134.

[markettech]

Two compressors in two years? They can't afford NOT to replace the unit in my opinion.

With what they'll have invested in swapping pumps twice now, they probably could have purchased a new 2 door....

I'm just sayin'

[mseng]

Two compressors in two years? They can't afford NOT to replace the unit in my opinion.

With what they'll have invested in swapping pumps twice now, they probably could have purchased a new 2 door....

I'm just sayin'

I agree and another benifit is more efficient unit lowing the electric usage making a quicker pay back.

[Snapperhead]

r409 is good for r12 units as well ... have any of that ?