[s-cars] R314a A/C - Can I charge it myself?

[Mock, Bruce J (Bruce)]

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Hey all!

I'm fortunate enough to have a '93 S4 that has a  factory R134a Air conditi=
oning system.  NOT R12 thankfully  (price of R12 is getting pretty scary)

So I'm wondering...  I suspect that my car's system charge is a bit on the =
low side... Should be possible for me to DIY check and add some add'l R134a=
 if it is indeed is low, correct?

In the good 'ol days I used to check on an R12's charge condition by observ=
ing the rate of 'bubbles' flowing past the little sight glass on the system=
's receiver/dryer.  (many bubbles=3D low charge, very few bubbles =3D syste=
m charge about right)  Do these same rules apply on an R134a system?  I kno=
w I can bop down to the local Parts-Is-Us and buy a can of 134a and a hose =
kit - but should I even mess with it or leave it to the 'pros'?

Any BTDT or opinions appreciated

Thanks!

Bruce - '93 with cool but could be colder A/C -  Mock