1993 240, R-134a.

I only use AC on a few days during the summer, and mostly to clear the inside windshield on cold, rainy days the rest of the year. So, the thing gets exercised from time to time. I even switch it on so every now and then to see if it's still working. The last time as in May, and it seemed to be OK.

Now we are having a couple of days that justify running the AC, and I found that the compressor cycles off and on about every five seconds. Having gone through the archives, I understand that this usually means low refrigerant, probably, from a slow leak, although I don't see any evidence of such.

So, I got a can of refrigerant and one of these charging gadgets with a dial from the auto parts store and connected it to the low pressure port to check for signs of life which, with an ambient temperature of 75° are the following:

As the compressor switches on and off the gauge needle moves back and forth between 20 and 50 psi. When I switch the AC off the needle moves to 60 psi and stays there.

I'm inclined to put in a can of refrigerant to see what happens, but before I do, I would like to know if that would be a sensible move, or if I'm likely to do more damage than I have to deal with already.

Thanks,

Bob S.

--
‘62 PV544 (B20, M41), '71 142E (Ex-automatic, now carbed), '93 240 Classic Wagon.