Hello again to all!

Been awhile since I bothered you with a question, I thought it was about time.

First a quick update - the Montero resurrection is continuing on at a snails pace (as money/family permits). I added some synthetic oil to the transmission and got 3rd gear, now I am only missing 4th, which isn't really needed :-P. I was hoping to get the transmission rebuilt this year, but instead I bought two retread tires that I am really happy with from treadwright - made it through a mud field in 2hi with them, traded a friend some work for bumpers and added a winch.



Anyway, on to the question. Although this doesn't concern the Montero directly, I am planning on fixing the a/c eventually - so it will be applied to it as well.

My wife tried to remove a guard rail with our Expedition, so the condenser along with several other items had to be replaced. Due to shoddy repairs whoever installed it failed to seat the o-ring prior to tightening the hard line to the condenser which caused a leak. I decided it was about time to learn how to work on an A/C system and I goofed.

The system still had pressure/suction (?) it hissed when I very carefully pushed the connection back to where it was supposed to be and tightened it. I took this hiss to mean it still had vacuum/pressure so the system was good to go.

I bought a recharge kit and actually read the directions. I turned the A/C high/max all the way up, and checked the the pressure - not enough pressure added a can... added another can, still wasn't enough (rear A/C - so I assumed it had a ways to travel). Added a third can (like 52 ounces now), still wasn't enough.

Long story a little shorter - the "auto climate control" was turning off the compressor, and there is an emergency pressure relief valve some where that pops when it finally does turn on and the needle gets way up in the little red bit on the dial.

I assumed I had at the very least destroyed a relief valve, but not only can I not find it (on the truck or on any forums), but the A/C is working great with no leaks that I can tell and after carefully recovering some of the freon to specific EPA standards *cough* - the pressure is now correct... Anyone ever heard of this happening? Or if you have heard of it is there something in particular I should be looking to repair after overcharging?

I do apologize for the non Mitsubishi vehicle used, but I am hoping a few of you have tried at home AC recharges...

Thank you,
Ryan

The relief valve did what it is supposed to do, release the excessive pressure from the high side of the system. If it is not still leaking, it is OK. (Spray some soap water on it and look for bubbles) High pressures may eventually destroy the compressor if you run it a long time, but if it's working, and not making "Rod Knock" noises, it's probably OK.

I hit the pressure releif on my Gen1 4.3 truck when I was charging it for the first time...

It sounds like a machinegun, and will scare the crap out of you.

Very good info here.. If I my add ... A lot of time if its over filled the 'cooled' line will freeze ,frost, up at the firewall if over filled on a run with the A/C working hard ...

A "Shady Tree" method of judging the charge in the system is to keep your hand on the suction line and the inlet line as it comes out of the firewall from the evaporator and feel for the temperature change as you charge it.

Have the fan on high, temp set to cool, outside air. As you add refrigerant, you will start to notice the larger suction line getting colder. Once it gets as cold as the inlet line, stop charging. If you have a temperature probe, you want the outlet line temp a couple degrees colder than the inlet line temp. This is showing you have a full charge. This method works well if you have a system that uses an orifice tube in the liquid line from the condenser.

If you have evaporator valve operated system, you have to check the line temperature as it comes out of the valve, usually right at the evaporator coil, which may not be easily accessable.

A simpler way is to simply feel the suction line as close to the firewall as possible and stop adding refrigerant immediately once it feels icy cold.