Advice on use of copper washer

[scottjeffrey]

Hi All and thank you! I am revamping an old 1974 car's A/C system and will be using flare fittings at the two evaporator connections. I am confused as to whether I am supposed to use a copper washer in each. All fittings are new except the evaporator female fitting for the compressor hose and it looks to be in good shape in terms of its threads and surface. Many thanks!
Scott

[red beard]

if the lines and fitting are copper you can but do not 'have' to use copper washer,
If the lines and fitting are aluminum I would recommend against a copper washer,
dissimilar metals fight- one looses- i believe it to be the aluminum in this case, either way the less the fighting car parts do with each other the less loosing there is to be had down the road.
I know Spruce Aircraft sells aluminum seal washers for 37 degree flare fittings (JIC) aka (AN), but unsure if they have aluminum seals for 45 degree (SAE) flare.

[Dougflas]

I only used to use copper sealing washers on flares that had a sealing problem.