This is the rear liquid hose that connects the outlet side of the filter-drier to the expansion valve inlet at the firewall.
CONVERTING MOPARS TO 134a
Until 1995, most cars with air conditioning used R-12 Freon refrigerant that is said to have a negative side effect of damaging the ozone layer and is no longer produced in most countries. since then, the industry standard has been R134a, which is an efficient replacement. Contrary to popular belief, most cars originally equipped with R-12 can be converted to 134a and still keep you just as cool.
Change or restore the filter-drier.
Drain the compressor oil and recharge with 134a compatible oil. (PAG or Ester Oil)
Insure that the system is clean and free of contaminants (Depending on component condition, this may be a simple matter of blowing out with compressed air or liquid flushing with an air-conditioning flushing agent)
Replace or restore all rubber hoses with barrier hose.
Remove EPR valve from compressor’s suction port
Charge with 134a between 70-80% of the original R12 charge amount.
Ignore the sight-glass. A properly charged 134a system will likely show bubbles in the sight-glass.
Typical 134a charge rate will be approximately 70-80% of the factory R12 charge amount.