Richard J Kinch wrote:
R-12, R-22, and R-134a all have a distinct solvent or medicinal type
odor.

DuPont and I would describe the odor as 'slight ethereal, but most
people can't smell it in concentrations below about 20%.

http://msds.dupont.com/msds/pdfs/EN/...2f80007210.pdf

Physical Data

Boiling Point : -40.8 C (-41.4 F)

Vapor Pressure : 151 psig @ 25 C (77 F)

Vapor Density : 3.03 (Air=1.0) @ 25 C (77 F)

% Volatiles : 100 WT%

Evaporation Rate : 1 (CCl4=1.0)

Solubility in Water : 0.3 WT% @ 25 C (77 F)

pH : Neutral

Odor : Slight ethereal

Form : Liquified Gas.

Color : Clear, Colorless.

Liquid Density : 1.194 g/cm3 @ 25 C (77 F)