30 year old brand new Ford AC compressor hard to turn

[waid1017]

I found a brand new Ford OEM never used or mounted AC compressor and it was sealed with the caps for my Ford 5.0 V8. It was full of thick viscous Mineral Oil which I drained. The compressor is little hard to turn which I assume due to the viscous oil. I dont want to do anything and ruin it.

Should I put in PAG oil or use AC flush to free it up ?

Thanks!

[Tim]

Never place a flushing agent in a compressor.

[tbirdtbird]

Since it already had mineral oil, I would suggest you use ester oil, not PAG. Ester mixes better with traces of mineral.
I would load it with ester, rotate it a dozen times, drain, and then you should be good to go.

However, there are 2 things to keep in mind.
1) At 30 yrs old the seals may be dried up, and that may be why it is hard to turn. I have had this happen with other 30 yr old NOS parts such as brake cylinders, rear main seals, etc etc
2) Whatever refrigerant you want to use now may not be right for the compression ratio of that compressor, which was designed for R12

Given the work involved in changing out a compressor, if it fails after the install, you have spun your wheels.
If it were me, I would pass on it and get a new one from the site sponsor, Tim. His prices are remarkably good.