Do our trucks use a TXV (Thermal Expansion Valve) or an Orifice tube? If they use an Orifice tube, can someone tell me EXACTLY where it is?

I picture would be a bonus!

 

Orifice tube. It's on the passenger side, in a vertical line, next to the condensor, in front of the radiator.
On the left in this pic.



Chris

 

Thanks Chris. I'll take a look tonight - it didn't appear to have one (A/C never worked very well anyway since new... hmmm).

Another question. I took off the fluid line to properly flush it. While air/flush pass through it, it seems to be clogged. I would think that the flush would pass through it better. This is why I originally thought that the orifice tube was inside the fluid line...

 

You should not need to flush anything unless you have had either a catostrophic compressor failure or a line broken in such a way as to allow trash to get into the system. I avoid removing lines to open up a system because when this is done you usually cannot get the system sealed back up in a short enough time to keep the dessicant bag in the drier from depleting itself absorbing moisture. When that is the case you mus replace the drier.
I have this exact situation myself. I just bought a 1996 and the conduit for the snow plow wiring rubbed through the liquid line, just above the orrifice tube. I will be replacing that line, the orifice tube, and the drier, because I am sure the drier is junk now. I won't be fluching anything unless I find debris when I am doing the other work on the system.

Chris

 

Thanks Chris - understood. In my case it turned out to be an unexpected compressor failure (it siezed). Originally I thought it was the clutch (it was shot) and tried to replace it only shortly learn thereafter that the whole unit was shot. Metal shavings were sent through the system along with the burnt up oil (black death is what I think they call it).

I don't want to mess with it again - so I'm redoing everything that I can and flushing the rest many many times and hopefully will have to do it only once. It's really common to have successive failures due to contamination.

 

Oh, so you're gettin a new drier anyway.

Chris

 

Thanks everyone. I've owned this truck since new and it's never had A/C work done on it. The A/C has always worked so-so, I just figured it was because it was a truck or a diesel.

Come to find out - there was NO Orifice tube in it. The new purple one I have fit exactly were all of you said it would. THANKS !!!

Another (repeat) question, however: While flushing the fluid line, while flush passes through, it seems to have a slight constriction. Is this normal? My fear was that my truck/year combo had some wierd fluid line design that had the orifice tube inside the fluid line. About 1/2 up the line is an obvious connection where the factory welded/soldered a joint. I'm paranoid right now that something (another orifice tube) is in that joint (which can't be opened unless the tube is cut). Ideas? Or am I just being paranoid?

 

I'm out on a limb here, but what if the orifice tub was defective and disintegrated/broke aprt, allowing the pressure to move it further up the line to someplace where it jammed?

Just so you understand why I would suggest such a wild idea, your AC would not work without an orifice tube. That what causes the gas to turn back into liquid. I'm betting it's further up the line. This may also be what it has always been marginal in performance.

What about snaking something through the line? I don't know that a standard snake would be small enough to do it. A fish tape might, but that depends on how sharp the turns are.

Chris

 

Chris - you may be right. There are too many bends for the tube to fit up the line. Please take a look at my webshots album: Truck A/C

Notice in the first 3 pictures that there is NO way the orifice tube fits where we think it does. It's the right one (purple) but you can clearly see that it is too long to fit in the condenser and the other end is too big to fit in the fluid line coupler.

The last 3 pictures shows the "seam" in the liquid line. I think the orifice tube is in there. There is no way I can cut it out, put in the new one and repair it. I did snake a wire up there like you suggested and it would go no further than that area.

I am half tempted to cut the tube there and see for myself - it would ruin it, but what the heck - I ain't got no A/C right now and what's another $50 for the line when I've dropped $500 in parts already.

 

My bad. I went out and checked, and compared my 99 to my 96. You are righter than I.
Orifice tube location on the 96. You can tell because of the dimple in the line below the connection.



Same location on the 99:



Orifice tube location on the 99, right in front of where the air filter box would be, on the fender (inside the aluminum insulation). I KNOW this is the correct location because I felt the line with the AC running, in front it is warm and behind that location is it ice cold. That IS the orifice tube.



Looks like they moved it between 96 and 99. I assumed it was in the same place. Sorry for the mis-information.

Now my question is how are you supposed to replaced just the tube on a 99? It appears that you must replace the entire line, unless it breaks apart under that insulation (I did not remove my insulation to see). I will ask my mechanic buddy tomorrow.

Chris

 

Talked to my mechanic buddy today, and he confirmed it. The orifice tube is in the middle of the liquid line, and the entire line must be replaced to replace the orifice tube.

It's nice to know for sure, but makes me question what the DC designers were smoking when they designed this. I can't see how it saves money as it would be more difficult to manufacture the line and weld/solder it together than to just put it at one end of the line. Makes me think conspiracy to generate parts revenue down the road.

Chris

 

Thanks Chris - you've been a big help.

I'm off to Chrysler to make another donation...

 

If your comp has shredded itself and pumped the aluminum powder throughout the system, make DARNED sure the condenser didn't receive any pieces of plastic piston ring material deposited inside. Some A/C comp's have plastic (glass filled Teflon) piston rings, and when a compressor commits suicide, chunks of those rings can work out between the piston and cylinder and get pumped downstream..
Take the condenser loose and get a good air compressor and fill the condenser with flush liquid and really BLAST anything out backwards... Sometimes you'll dislodge any foreign matl, but if you don't get all that black death and trash out , you'll be eating another compressor, or at minimum you could clog the orifice tube screen.
An evaporator is a more difficult matter . Those things are danged hard to clean no matter what. Same consequence.. if insufficiently cleaned, new comp won't last.
If the system is really badly contaminated, you MIGHT want to consider just replacing the evap. I learned this the hard way...

FYI, most automotive OEM's use PAG oil (polyalkene glycol) because it's cheap. This stuff is extremely hygroscopic, so when you plan to go back with new oil for the compressor, and if the new comp is not already pre-filled with PAG oil, use POE oil (polyol ester) as it is not hygroscopic. It's a bit more expensive than PAG and is perfectly compatible with R134a.

Good luck
Keith