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Old 07-09-2018, 12:20 PM
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Originally Posted by Bugout4x4 View Post
Just ran into something important that needs to be shared. Was topping off the system in my Truck and found something we all need to watch for. Apparently they are putting out cans with improper instructions on the side.



This is INCORRECT! Freon R134a cans like this need to always be held upside down to charge the liquid rather than the gas into system. Getting enough Freon in the system to make it work properly as a gas before encountering an over pressure issue is next to impossible. It needs to go in slowly as a liquid.

I tested this can to see if it may have a tube attached inside that went down into the liquid like a paint can does and it did not. I was only getting liquid when it was held upside down as all other R134a cans do. So this arrow is backwards and is going to cause problems properly recharging systems.

Keep an eye out for this discrepancy guys. You can tell if you are getting liquid because your gauge needle will not remain steady as it goes in, it will flutter a bit as the liquid is going in.
The instructions on the can are correct. For anyone that's not sure of the proper procedure on adding freon do a search. Many people add liquid to the suction line as a short cut but to say the instructions on the can are wrong is not true
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Old 07-09-2018, 01:03 PM
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Originally Posted by missedbass View Post
The instructions on the can are correct. For anyone that's not sure of the proper procedure on adding freon do a search. Many people add liquid to the suction line as a short cut but to say the instructions on the can are wrong is not true
I will respectfully disagree. R134A is a blend of refrigerants that are heavier and lighter than R12. If you add vapor only, the lighter components boil off and leave the heavier eventually. This would give you a different, although colder temp in the evap coil than intended. This might seem like a good thing. But for the evap coil to seem cold, it needs a certain amount of liquid in it that is of low temp to contact the metal of the coil. Thus the lighter components would be colder, but not impart as much lack of temp to the metal in the coil. You need to get the proper blend into the system and the only way to do that is to introduce liquid into the suction line. However you are not supposed to dump the whole can all at once. No one advocates that
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Old 07-09-2018, 01:38 PM
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Originally Posted by 4.3L XJ View Post
I will respectfully disagree. R134A is a blend of refrigerants that are heavier and lighter than R12. If you add vapor only, the lighter components boil off and leave the heavier eventually. This would give you a different, although colder temp in the evap coil than intended. This might seem like a good thing. But for the evap coil to seem cold, it needs a certain amount of liquid in it that is of low temp to contact the metal of the coil. Thus the lighter components would be colder, but not impart as much lack of temp to the metal in the coil. You need to get the proper blend into the system and the only way to do that is to introduce liquid into the suction line. However you are not supposed to dump the whole can all at once. No one advocates that
What you are talking about is an azeotrope, refrigerants with different boiling points and glides. R134a is not azeotropic.
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Old 07-09-2018, 01:46 PM
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Originally Posted by 4.3L XJ View Post
I will respectfully disagree. R134A is a blend of refrigerants that are heavier and lighter than R12. If you add vapor only, the lighter components boil off and leave the heavier eventually.
Although that is the case for the R12 "drop-in" replacements on the market such as Freeze-12 , this is the first I've heard of it for R134a. A quick web search reveals that R134a is 1,1,1,2-Tetrafluoroethane, a single chemical compound consisting of two atoms of carbon, two atoms of hydrogen and four atoms of fluorine, chemical formula is CF3CH2F. I have not found any reference to it being a blend of multiple refrigerants.

FWIW, here is the charging procedure recommended on a forum frequented by professional AC technicians:

https://forum.aircondition.com/forum...ve-a-c-systems

Bottom line appears to be that either method will work, but charging as a liquid is considered riskier although it is faster. (I've had very good success charging as a gas by warming the can so will be sticking with that.)
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Old 07-09-2018, 03:20 PM
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Originally Posted by Rambler65 View Post
Although that is the case for the R12 "drop-in" replacements on the market such as Freeze-12 , this is the first I've heard of it for R134a. A quick web search reveals that R134a is 1,1,1,2-Tetrafluoroethane, a single chemical compound consisting of two atoms of carbon, two atoms of hydrogen and four atoms of fluorine, chemical formula is CF3CH2F. I have not found any reference to it being a blend of multiple refrigerants.

FWIW, here is the charging procedure recommended on a forum frequented by professional AC technicians:

https://forum.aircondition.com/forum...ve-a-c-systems

Bottom line appears to be that either method will work, but charging as a liquid is considered riskier although it is faster. (I've had very good success charging as a gas by warming the can so will be sticking with that.)
Good article
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Old 07-09-2018, 04:59 PM
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Originally Posted by missedbass View Post
Good article
Interestingly the recommendation there is to do an initial liquid "flood" of an empty system through the high side with the engine off, then charge the rest through the low side (gas or liquid) with the engine and compressor running. Makes sense, will have to give that a go next time.
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Old 07-09-2018, 05:11 PM
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Wow this is a great thread and has me even thinking about fixing my a/c myself. Hmmm.........hopefully not much different on a 92 xj.
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Old 07-09-2018, 05:38 PM
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Originally Posted by offroadman83 View Post
Wow this is a great thread and has me even thinking about fixing my a/c myself. Hmmm.........hopefully not much different on a 92 xj.
I'm not sure what year the XJ was switched from R12 to R134 refrigerant. If yours is an R12 system you'll probably want to convert it if that has not already been done. (R12 is still out there but is $$$.)
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Old 07-09-2018, 05:44 PM
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Originally Posted by Rambler65 View Post
Interestingly the recommendation there is to do an initial liquid "flood" of an empty system through the high side with the engine off, then charge the rest through the low side (gas or liquid) with the engine and compressor running. Makes sense, will have to give that a go next time.
I was always taught never to add liquid into a system under a vacuum. I always break the vacuum with vapor first. The high side gauge will not read "hg but will still be in a vacuum .
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Old 07-11-2018, 02:25 PM
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Ok, checking back in here. Sorry for the delay, it's been a busy week with the kiddos and the such.

So I definitely have R134a. The sticker in the engine compartment indicates R134 and has the Chrysler logo, so I have to assume it's factory. Apparently for 1995 they made some XJ's with R134 and some with R12.

Looking at my hoses under the hood and at the pictures on Rockauto, it appears that all the fittings are threaded. Also someone mentioned that I should replace the liquid line with the orifice tube. However all the parts retailers are listing the liquid line as -without- orifice tube. The parts retailers indicate a block type expansion valve which I can definitely see under my hood. Would this mean I have no orifice tube?

Also if anyone knows where the liquid tube is hiding on my Jeep, please let me know - I can only see the 2 lines out of the firewall and the stuff around the receiver/dryer.
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Old 07-11-2018, 07:40 PM
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If that is a block and looks like it has a little hat on it, that is a TXV valve. Ans as I posted before, they charge differently than one with an orifice. The gauge on the can is worthless for this system
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Old 07-12-2018, 11:49 AM
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Yep I said that about the liquid line thinking Chrysler used an orifice tube/ accumulator setup in 1995 but I was evidently mistaken since you have an expansion valve/dryer setup. Only had my '98 to go on. Sorry for the confusion, my bad
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Old 07-12-2018, 02:34 PM
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This thread has encouraged me to get my AC working. It hasn't worked in 2 years but I know the compressor works but I could never track down the leak. With no pressure in the system I just order everything new except the compressor... I wont be recharging it myself but at least I know everything else is new.
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Old 07-12-2018, 03:30 PM
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Originally Posted by rheacox View Post
Yep I said that about the liquid line thinking Chrysler used an orifice tube/ accumulator setup in 1995 but I was evidently mistaken since you have an expansion valve/dryer setup. Only had my '98 to go on. Sorry for the confusion, my bad
No worries - I'm slowly but surely working down the path to understanding/fixing the system.
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Old 07-12-2018, 03:47 PM
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So does anybody know IF I have a liquid line on my 95 R134a system, given it's the "expansion valve/dryer" setup and if so, where it runs? The parts retailers DO list one for the 95 but I don't see it (or I'm failing to recognize it) when looking in the engine compartment. It states it runs from the evaporator to the condenser, so it should be from the firewall somewhere to the front of the radiator.

Another question, can anyone confirm that if the lines look like threaded fittings that they definitely are? Assuming that they are all threaded (as it appears they are) can I (should I) use PBBlaster if necessary? What about heat?

Sorry for my ignorance. Once I know the answers to these questions, I think my plan will be to order a new R/D, Expansion valve block (since it's like $11 on RockAuto) and O-Ring kit and do the O-rings and new parts. Assuming I don't break any other parts in the process and that everything goes back together nicely - then I'll move on to purchasing the vacuum pump/gauges etc.

Someone mentioned that the pressure readings are not useful for my type of system and that I have to use the inspection port. As far as determining the proper amount of refrigerant, since my system is completely empty, I would just use the capacity spec (which someone mentioned is listed on the under-hood sticker), right? If this is the case, does that mean the gauge set is useless or not? I'm getting a bit ahead of myself, so I can burn that bridge when I get there.
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