Does ester oil=r134 conversion?

[Glenn_tx]

The compressor on the 78 wagoneer I have has a tag dated 3/98 on it that has ester oil in big blue letters. Does this mean it has already been converted from R12? Works fine, a little noisy, just curious.
Thanks in advance.

[porchpiggy]

Ester oil is generally used in converting to 134 because it is compatable with 134 and r-12. You should be able to tell if it has been converted by the fittings. 134 ones are different then r-12 so you won't get them mixed up.

[Glenn_tx]

I'll give the fittings a look. I do know that the hoses have been cut and tightened with pipe clamps.