Hi, 1990 Ram Van , How can I tell if the AC system has been converted to the newer 135 Freon?

 

There should be adapters on the test ports.

 

FYI, it's R134a, and as far as I know, there's no such thing as 135 freon. Just pointing it out in case you have to ask around.

 

If the caps on the charge ports are both the same size and have a cap like the one on your tire stems, it's R-12. If they are different sizes, it's been changed to R-134. Whether it was done right is a pot luck dinner. I've known guys to just evacuate the system, put conversion adapters on the lines and dump R-134 in. The oils used aren't compatible with each other.

 

I would put a lable under hood showing it was converted pretty sure you can get these I used perminent black marker on my 92 jeep when I did mine

 

another thing is...

a consumer hasnt been able to get 12 since the early 90s...
most shops phased it out by the mid 90s too
134 will work in most all 12 systems as long as all the old oil is taken out of the 12 system - 134 optimally wants to use around 1-2 lbs for optimal cooling in cars...12 takes more and hoses are larger - so 134 works - just not as good

 

And we are resurrecting a year old post why?

 

Eh! Why not?

 

Because the op's question was answered May of last year and he hasn't been here since Aug 18, 2024. But we can discuss why newbie's don't look at the post dates.

 

When I first got here several years ago, I did a web search for a particular question. The search led me here. I've been here ever since.

I figure someone might pop in and never, ever, come back. Others might come here and stay and contribute some minor detail that will solve a problem others have. The more the merrier!