Having trouble charging A/C - help!

[PlumCrazyChris]

I spent many hours last night trying to get 134A into the system. I've done this on many vehicles and 2 other FSJs, but years ago. I put my old Robinair guages on both ports and pulled vacume from both hi and lo pressure sides. I pulled a strong vacuum 30psi for about an hour, left it for 15 min, no leaks.

It was actually partially charged with R12 (the compressor was coming on) when I got it, but wasn't blowing cold.

I then attached an oil charge/134A can, started the jeep, turned on the AC on high and tried to introduce some oil/freon. I put the can in a cup full of hot water, and nothing. it wouldn't take any.

I went to the manual, and tried to put both compressor service valves in the Mid Position, but still nothing. It won't take any coolant....

I repulled the vacume, twice, I tried to charge the lower service port, thinking it might be backwards and the lo pressure were be swapped, ( the manual shows it both ways...)

Went back to the top service port, and pulled a vacume and then tried to charge again. Still wont take coolant.

I can't figure it out. Anyone have any ideas?

https://photos.app.goo.gl/wRto8zRBr7tE96659

[PlumCrazyChris]

https://photos.app.goo.gl/mxuZSFTCQyvBGmrd7

Not sure why the photos are not displaying, but the link should work. This is the page of the manual that shows the service port positions...

[babywag]

Did you rev engine to ~1500rpm?
When you tried to charge it initially did the compressor clutch kick on?

Sometimes you need to jumper the low pressure cutoff switch if clutch does not kick in.

[wiley-moeracing]

I am a little confused by your post, 1st, are you trying to convert a r12 system to a 134 system? Do not mix the two. Are you sure you have the valves in the correct position, and do you have the correct connections for the service ports? r12 is different than 134. You may have pulled a good vacuum but only in the hoses, not the system. The newer 134 cans use a different valve tap than the older 134 cans, do you have the correct one for the cans you have? If you are doing the conversion, make sure it is a kit that comes with the correct ports/fittings and flush the system completely, replace the drier/filter with 134 type unit, replace the orifice tube with a 134 type, make sure you clean the compressor out of all the old oil and refill with the 134 type oil. Your charge levels will be different than the r12 levels so you will have to experiment with refill till you get good numbers on the gauges. Sounds like you have a mis-mash of stuff going on, you may want to contact a shop for help?

[SJTD]

What Wiley said. I also understood from your prose that you may be adding 134 to a system with mineral oil for R12 in it.

If the system is unconverted you can buy compatible replacements that work well but are flammable.

[Mikel]

Have a look at R152A. It is used in keyboard duster sprays (very cheap), but it is a proper A/C refrigerant that supposedly works very well in R12 systems.

https://www.youtube.com/watch?v=i4uAXDyICsA

[PlumCrazyChris]

I am a little confused by your post, 1st, are you trying to convert a r12 system to a 134 system? Do not mix the two. Are you sure you have the valves in the correct position, and do you have the correct connections for the service ports? r12 is different than 134. You may have pulled a good vacuum but only in the hoses, not the system. The newer 134 cans use a different valve tap than the older 134 cans, do you have the correct one for the cans you have? If you are doing the conversion, make sure it is a kit that comes with the correct ports/fittings and flush the system completely, replace the drier/filter with 134 type unit, replace the orifice tube with a 134 type, make sure you clean the compressor out of all the old oil and refill with the 134 type oil. Your charge levels will be different than the r12 levels so you will have to experiment with refill till you get good numbers on the gauges. Sounds like you have a mis-mash of stuff going on, you may want to contact a shop for help?

That's right, converting the system. I've done this many times and it works fine as long as you add the correct oil as well.

As you noted, I pulled a vacuum, and therefore no more R12 in the system to mix with 134A. Have all the fittings, robinair guages, vacuum pump, and can even make my own hoses. Did I mention I've done this before? Joking aside, I do appreciate your input and I thank you for it.

[PlumCrazyChris]

Finally got it blowing cold! As Wiley mentioned, I just needed to get the dang service valves in the correct mid point positions to allow the system to accept coolant and read the pressures correctly.

I ended up with a full charge can of oil/134a, and 2 full cans of 134a. The low pressure side is still a little low, so I might add part of another can and see if I can freeze myself out!

Thanks again for your help guys!

['89_Wagon]

Did you replace the expansion valve? Mineral oil can get stuck in there and the valving is different for r134a vs r12. Might explain the pressure issues you are having.

[PlumCrazyChris]

Did you replace the expansion valve? Mineral oil can get stuck in there and the valving is different for r134a vs r12. Might explain the pressure issues you are having.

Good thought 89 Wagon, I think the pressure issue 20 vs. 22 psi, is actually just a matter of needing more 134a. I had so much trouble initially, I think some of the coolant didn't make it into the system. Its blowing cool, need to measure it, and I'll top it off this weekend likely when I have time.

Thanks so much for your input.