1997 4 cylinder.

Bought the car from my brother. He had it for 5 years and never had the AC serviced. No AC history before that. The AC works ok, but I'm guessing that it is at least a bit low on R134 as I understand that all these systems lose a little refrigerant over time.

Is there a way to estimate if the amount of refrigerant is adequate? For example, measure the ambient air temperature and then measure the AC temp at the vent? Would the differential temperature be a good indication? If so, what should the differential temperature be for an AC system in good order?

Leave well enough alone or have it serviced?

Thanks in advance for your help

 

Below is a good write-up, including charts for the proper AC vent temperature range for Hondas.
Refer to the "Performance Temperature and Pressure" chart.

https://drivrzone.com/proper-auto-ac-vent-temperature/

 

With an ambient temp of 83 the AC temp at the center vent was 41, which according to the chart in my post above within specs. I'll leave well enough alone.

 

I'm of the opinion if it ain't broke, don't fix it. It usually gets me into more trouble than it's worth.

If or when the a/c charge causes performance issues, you are best to go through the system and replace the o-rings, receiver dryer, etc, then evacuate/recharge the system.