Hello back again, so I recently recharged our AC on our Durango as it was low and haven't recharged in since 2013 after recharging the system thru the low pressure side with the AC on max watching the pressure gauge as I fill it not to make it go into the yellow or red. The air was a cold as new but a day later when I went to turn on the rear ac (still doesn't leak yet) the AC clutch engages and disengages in a 4 second period, turning the rear ac off fixes the issue, I decided to check the pressure with the car off and it's in the yellow turn the car on and front ac on its in the green, when i turn on the rear ac the gauge goes to the red with the AC clutch engaging and disengaging. Keep in mind that it only goes to red when the clutch engages then yellow when the clutch is disengaged. What would cause this? Also when charging the system I had the rear ac on and it was cold but a smidge warmer than the front. Original compressor and clutch 280k miles

 

You cannot accurately charge any AC system with one of those cans that just hooks to the low side (not to mention that stop leak crap they usually out in them). The only way to know what the charge is would be to have it evacuated then charged with a known weight.

 

Measure it again with all the AC running and the car on and tell us what you find.

 

That still doesn't give you the whole picture of what's going on in the ac system. You need to know both the low and the high side pressures, which those little cans won't tell you. You also need to know that the system is properly charged so that the expansion valve is getting liquid and not gas. The only way to know that is to know what the weight of the refrigerant in the system is or to have a sight glass (which we don't).

 

You're 110% right.
However I would assume he doesn't have a full gauge set, would rather not buy one right now, or pay somebody who does have one to look at it.
By having the engine running with all the AC on and just the low side gauge on there, one could have a good chance of figuring out what's wrong, if it still bounces on the low pressure cutout it's most likely low on charge again. (I stress, most likely)
Then from there one could either quickly and cheaply try to charge it up with walmart refrigerant, or find some more proper tools and do it the right way.
Either way, it doesn't hurt to first check it out more closely with just the low side gauge.

After re-reading the original post, it appears you did try letting the car run with ALL the AC on, is this correct? and it would keep tripping out with the needle in the red? If so, it is most likely low again.

 

But if you get stop leak in there no ac shop will touch it. And if you don't tell them there's stop leak in it and it gums up their machine they're probably going to be after you for a couple grand to replace or repair it.

 

Certain shops may feel that way,
and also not all cans off the shelf have stop leak.

 

I promise you every shop feels that way about their machine.