R134a cooling

[hgeranium]

My truck has factory AC and at some point in the past was converted to 134A. It’s leaked Freon since I’ve had it. From what it looks like it’s just the service ports. I can fill it up and it seems like the majority of it will be gone in a week. When it’s full for those first few days the truck will cool but it really isn’t the most effective. I have no idea how old the expansion valve and accumulator are. The compressor is dated 2008.
 

I wanted to hear about how cold I should be expecting a converted system to be. I understand it won’t be as effective as R12 but I’m assuming something has to be wrong. The compressor itself doesn’t make any noises in the clutch engages just fine. Can anyone with a thermometer or thermal/temp gun and good working 134a AC tell me what degrees they’re getting from the vents? I will have to get a little thermometer to check on my own but just so I have a baseline

[Gjeep]

My opinion is to replace all components so you know your starting point and it's reliable. 

[hgeranium]

2 minutes ago, Gjeep said:

My opinion is to replace all components so you know your starting point and it's reliable. 

That’s my plan but I just want to make sure that I should be expecting better cooling once I replace the parts

[hgeranium]

I have also never done a lick of AC work so I’m kind of worried about having to replace some of this stuff

[eaglescout526]

You’ll get good cooling out of 134a but nothing like modern cars that run it. The problem with 134 is it needs a big cooling surface to effectively work and cool properly. 
But at the back of the air box from the middle vent I’ll see temps in the 30’s. But once it comes out of the vent it’s probably closer to 40. Overall I’m happy with the performance as my MJ never had AC from the factory so anything is better than 110* out here. 
 

But it sounds like to me when it was converted, the proper o-rings weren’t used. Change all those out, probably the expansion valve too if that’s still rated for R12. Usually they are stamped with 134 on the block. And replace the schrader valves in the service ports while you’re at it so that way if you have a leak, it won’t be from degraded valves at the service port. 
I’ve gotten to the point now where I’m not afraid to service my own AC systems. 
 

Oh also in case you don’t know, 134a becomes acidic when in contact with moisture which will result in tt eating away at internal components. If you plan to do this all yourself make sure the dryer is replaced as well and that the humidity is low or very dry. Course don’t charge a system until you know it can hold good vacuum. 

[llhat]

get the service port leaks repaired,   "maybe" as simple as new schrader valves.

 

my 89 had r12,   local shop found the rubber hose behind battery going to the condenser was leaking...  and it was deteriorated internally... 

could not easily get to the condenser fittings to replace as a unit, but these guys were good..  silver brazed new fittings to existing pipe

made a replaceable hose section, 
we went with 134a and it has been ok ever since...  ( knock on wood)  somewhere around 7 years now...  (guess)