sounds more to me like it's overcharged.

If there was a problem with the expansion device your high side would be too high and your low side would be too low. Right now, your high side is high and your low side is normal, if not a touch high.

 

I did a quick search and all of the TJ series Jeeps use a orriface tube NOT a TXV/expansion valve.

To be running 400psi its either grossly overcharged or you have airflow issue IE your condenser core is plugged or your fan isn't pulling WAY too little air over the condenser core. From those pressure, my bet is over charged.

What often happens is the orifice tube gets some trash it in and it causes a restriction. This causes the low pressure to go down and makes the compressor cycle on and off and it mimics the symptoms of a system low on refrigerant.

So what often happens is someone sees it cycling and buys one of those "gauge on a can" bottles of R-134A and starts filling the system till the low side pressure comes up to what it calls the "green zone". The problem is they have now grossly overcharged the system and its still not working.

Getting back to the orifice tube, its located in the line that goes from the condenser coil to the firewall. The tube is inside the joint where the tube bolts to the condenser coil. When you remove the line, look inside and there will be a thing that looks like a little plastic sock. This is the orifice tube. Some come out with just a pair of needle nose pliers, sometimes you need a special tool to pull them out.

Orifice tubes are really cheap so just buy a new one and don't bother trying to clean the old one.


FOG

 

To restate the events. The A/c was blowing a bit warm but was cooling. It's 95 out today. I checked the low side only. It was 40psi. The chart indicates 50-55 psi for 95 degrees ambient, so I added a half can. The compressor started to cycle. I put both guages on the lo side. I had overcharged to 60 psi, so I recovered about 6 ounces. I put guages on both hi and low. The actual readings at this time are 425 psi hi and 40 psi lo. The compressor is cycling but not as often. I'm thinking that by adding the leak stop 3 years ago and another can earlier this year have caused a problem with the orafice tube.

 

I used another can of leak-stop and my guess is that it has screwed up my expansion valve/orafice.

I bet when you pull your orifice tube the filter mesh is going to be gummed up with the leak stop. Leak stop one of the worst things to put in a A/C system IMHO. If your not able to fix the leak for what ever reason its allot better in the long run just to keep topping the system off with refrigerant than putting in leak stopper.

FOG

 

Do the clips just pop off or do I need a special tool to separate the line? I think I need to buy a 5/8" special tool. (Also, all air flow appears to be OK including air flow thru the condenser.) I did the leak-stop because I was told that replacing the evaporator is a major/major type job. Does anyone know of a DIY procedure? maybe it's time that I fix it correctly.

 

The Fog...thanks for taking the time to explain what I didn't.

And now knowing the backstory, I agree the orifice tube is likely clogged with stop leak.


I'd also comment that the condenser outlet is a bad place for an expansion device. Good engineering practice is to put it as close to the evaporator as possible. No telling how much capacity is lost from that...

Of course, The Fog and I, among others, are already facing a dilemma over Chrysler's engineering work with 05-06 OPDA gear.

 

I'd also comment that the condenser outlet is a bad place for an expansion device. Good engineering practice is to put it as close to the evaporator as possible. No telling how much capacity is lost from that...

Of course, The Fog and I, among others, are already facing a dilemma over Chrysler's engineering work with 05-06 OPDA gear.

For a load that varies as much as a vehicle A/C systems does (outside air temp,inside fan speed, engine speed) it should have an expansion valve but there is a pretty good substitute.

They make an orifice tube called a "Smart VOV" that is basically an orifice tube that has a pressure driven spring/needle. The needle opens and closes the orifice depending on high side pressure. I have one in my Chevy 2500 and my wife's ford and it makes a very noticeable difference in cooling at idle and slow moving conditions like stop and go driving.

Nartron Corporation - Smart VOV

On a side note, talking about not having the expansion device at the evaporator have you seen those mini-split A/C units. I looked at one for a friend of mine the other day and they have what LOOKS like a liquid line but its not. They put the orifice tube in the condensing unit outside so both lines are low side lines. Add to that they only have ONE gauge port on them for the low side, there is ZERO ports to check the high side.

I was starting to wonder if Chrysler had designed the dang thing

FOG

 

One of the local parts stores sells the entire line from the firewall to the condenser for around $35. Is this a better idea than just replacing the orifice?

 

wow that smart vov looks like a really cool deal. Next time I have one apart I might put one in...


I haven't looked closely at any of the mini-splits...I'm an engineer for a custom commercial and industrial air con/refrigeration manufacturer (5 to 500 ton)...we won't even put an elbow between a TXV and the evaporator, much less any length of tubing. In the past we would have an elbow on one of them if we were running two TXV's in parallel to the same evaporator circuit but now we're always using electronic expansion valves in those applications.

 

Replaced the entire low side hose from the firewall to the condenser. Did an autopsy of the orifice valve in the old pipe. It was completely blocked with the junk I added to try to fix the evaporator leak. All is well now but I am sure I will need to do the evaporator soon. Does anyone know where i can get the instructions for removing the dash?
Thanks for all the inputs.

 

Look at Jeep air conditioning components and complete A/C kits for all Jeeps. They have the instructions for installing their kit. It should be what you need.

 

Thank you!

 

I wouldn't worry about it unless you actually have any problems. You might have gotten lucky and caught most of the stopleak crap in the orifice tube.