Are you trying to find where the low side **charging** port is?
If so it is on the AC line closer to the radiator, The Hi side port is
closer to the firewall.
I seem to remember that the thread size on these 2 ports are different (to
prevent a mistake).
If I remember correctly this car used R-12 freon.
HTH
JerryR

"Fijoy" <tofijoy@gmail.com> wrote in message
news:73ed9aef-b623-4d89-a196-67dbb4dae59a@d38g2000yqi.googlegroups.com...
> Hi all,
>
> My 91 Accord is A/C system is low on the refrigerant because of a
> small leak. I know that when I recharged the A/C during the last two
> summers, the mechanics used the R134a refrigerant. This time, I am
> thinking of doing the recharging myself. I was wondering, where is the
> low pressure valve in this A/C system located? Thank you.
>
> Fijoy