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Discussion Starter · #1 ·
Hi all, I searched all over this forum but can't seem to find those elusive readings. Does anyone happen to know what the proper PSIs are for the high and low sides for a 1st Gen Trooper (1989)? My system has been converted to R134a if that changes the numbers at all.

Thanks in advance!
 

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Differences between R22 to R134a are negilable ... use the same amount of refrigerant and fill using the same port. You did get the TXV (Thermal Expansion Valve changed and a new drier put in did you or it will act a bit funny otherwise.
 

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Discussion Starter · #3 ·
This is mostly for a checkup since I want to make sure my system is working optimally. When I originally built the system, I had my low side set to hover around 35 and my high around 185 (with an ambient temperature of around 75). But this was only an educated guess since I couldn't find any definitive source that said what the proper PSIs are suppose to be. Was wondering if anyone happen to know.

Cheers!
 

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Apparently there is no need to change the TXV because it is a new enough design. Thats what I was told on my 90. But the dryer and the o-rings need changing.
 

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I work in refrigeration so I was being a bit facist about the TXV really. You can get away with it. As betterthanyou says drier and O'rings (forgot o'rings as I do them as a matter of course withouth thinking) fot the green ones are essential. The system should work fine without adjusting anything. The reason they went to R134A from R22 was due to its similarities in thermal properties and the lack of Ozone depletion of R134a and slightly less effect of global warming potential. As for values as follows:

Refrigerant Evap temp (celcius) at 1 bar Cond temp (celcius) at 26 bar
R22 -41 63
R134a -26 80

Thats all I can do to help unfortunatly. Not been working in refrigeration long. TXV's can be as new as you like, technically they are refrigerant specific though regardless of what people say.
 

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Well 4 seasons sells one for the Trooper. Would you advise changing it? It is less than $100
 

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Personally for a car I wouldn't really bother. Just make sure that the relavant O'rings are replaced thoughout the system, and the drier. Get the system properly recovered of the old refrigerant. Replace the schrader core (like car tyre valve cores). Get it leak tested by filling with nitrogen and holding it for an hour at pressure then going around all the joints with a soapy water mix and looking for bubbles. Once your sure the system is sealed vacuum out the system for at least an hour to ensure all moisture and water has been removed, then fill with the correct amount of R134a. The compressor should have the correct vlolume stamped on it failing that most car air-con places will be able to advise. Everything should be fine after that.

In the UK they are being quite facist about air-con ... well refrigerants as a whole. New legislaton has been brought in that you have to hold a particular qualification (F-Gas City & Guilds 2079) to handle any/all refrigerants and depending on the amount the system has you have to have different levels of the qualification. This legislation was enforced on July 4th this year, and is a crminal offense not to have the paperwork if you are in the business. Also in the UK there is a £20,000 fine and up to 5 years in the slammer for deliberate release of refrigerant. R12 was banned 11 years ago in new vehicles though you could still get it for refil's, however that dried up about 5-6 years ago and now all you can get is R134a. Just to make things even worse is new production of R134a is also being phased out and it will be illegal to install R134a in new cars and you have to use the latest alternative of HFO-1234yf (though tis is still some way off)

Oh and another thing you must do if changing from R12 to R134a is drain all the oil out of the a/c ststem and replace it with a PAG (Polyalkylene Glycol) oil .... as a cheap and cheerful way of getting this if you cannot get the correct stuff is to find some PAG brake fluid (It should say it on the back of the bottle) You don't need much and again on the compressor it should tell you the right amount.
 

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Yea I just had my re manufactured compressor go out on me a few days ago. I sprung for a new 4 seasons compressor that is supposed to run quieter and be more efficient. I flushed the whole system with cleaner and compressed air so it is free of all oil and I will do a fill on the system from scratch including new PAG oil. I noticed the condenser had black O-Rings when I took it out for cleaning so I will make sure I change all the O-Rings in the system just to be safe. There were no leaks but it is good insurance.
 
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