Best Compressor For R12 In Diesel Pusher

[philipswanson]

I have a 95 Wanderlodge that I am setting up for R12 from scratch. I am looking for a modern day compressor recommendation that will hold up well under stress with R12 and ester oil.

[Dougflas]

Sanden SD 507

[philipswanson]

Most 507s are set up for R134. Will one of these work if I just swap out the oil or are there other differences?

[Cusser]

Most 507s are set up for R134. Will one of these work if I just swap out the oil or are there other differences?

The replacement Sanden in my 1988 Mazda truck came with PAG oil in it, I needed R-12 mineral type oil. So I drained out the PAG oil, added about 4 oz. R-12 mineral type oil, turned the compressor at least 10 revolutions, then drained out the R-12 mineral type oil. Then I repeated the R-12 mineral type oil flush and drain.

Then I added the correct amount of R-12 mineral type oil and completed my install.

[bohica2xo]

Why would you "start from scratch" with R12?

Properly sized components work great with 134a. The cost of the components for a system is really no different for either refrigerant. The cost of R12 vs 134a is significant however.

[Cusser]

Good question bohica, as a 1995 would've been factory R134a, I didn't catch that.

[philipswanson]

I want to use R12 because it should cool down this coach better. I have been able to buy R12 pretty cheap when looking for deals. R12 cost is not a factor since I have way more than I would ever need.

[philipswanson]

What kind of oil should I use for my R 134 to R12 conversion? I am debating between mineral oil or ester oil. The lines will be flushed totally clean and purged with nitrogen. Which oil will provide the best cooling and approximately how much oil should I use in a 29 ft motorhome?

[bohica2xo]

Well, since 134a has a COP that is about 6% better than R12 - it is unlikely to cool any better when placed in an OEM 134a system.

But if you must use R12, at least use Ester oil. That way 134a can be used at a later date.

Oil quantity can be hard to determine on a pusher. If you have the OEM spec that is the best number. The alternative is to estimate line lengths and component sizes.

[philipswanson]

What is COP? You think R12 won't cool as good as R134? Everybody says it runs colder. True?