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AC question

aquilaone

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1992 Explorer
Hi,

New to this board, and preparing to repair AC system.. AC compressor went out on 1992 Explorer (retrofit 134a in 2000). I am replacing with new parts - the condensor, Orifice, accumulator, and hoses. Found a good used compressor I plan to use. Will flush the existing evaporator and metal lines.

I have read all the AC forum posts and an AC book from the library, and called ACkits (he wasn't very helpful).

I am not sure what oil to use... PAG 100 or ester? The retrofit used ester. Is PAG better, and is 100 the correct type?

Also, I am not sure if I have the correct Orifice Tube...Got a red O.T. from Advance Auto Parts. Wondering if I should be replacing with a Blue O.T. since it is retrofit. (there was a black O.T. in there with a lot of black gunk that looks like one of the more expensive variable OT)

Wondering if the parts I am buying are for the original R12 system, or if they are for either R12 or 134a.

Thanks for any help... I plan to start this weekend, and never knew how complex the AC system is.
 



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Welcome to the forum!

For oil, check what your new compressor recommends.

Orifice tubes should all be the same, only the O-rings will change on retrofit parts. Any parts you buy from a store should be R-134 but to be sure you could buy parts made for a 1994 Explorer, which originally came with R-134.
 






Ford uses PAG-46 oil in the R-134a systems. If you're starting from scratch with a clean system that hasn't had any oil in it before, you can use that. Ester is usually used when you have a converted R-12 system that still has the old oil in there.

Red orifice tubes are usually the correct ones for R-134a systems, but it depends on the brand. You can just use the regular R-134a tube for a 1994 Explorer with R-134a, whatever color it is. The variable tubes are better even though they cost more since they don't keep the system at such a high pressure.

If you've got black gunk in the orifice tube, your system may have "black death" and you will need to replace EVERYTHING - you cannot re-use ANY parts and will need all new lines, evaporator, EVERYTHING. If the system has black death and you re-use any single part, it will contaminate the system and you will have wasted a lot of time and money to have a system that will work for awhile, until it fails from the contamination - then you will have to replace everything or repeat the cycle yet again until you do.

Almost everything Advance sells (condensor, accumulator, and hoses) is R-134a compatible, just be sure to get the R-134a temp switch (they sell an R-12 one still) and use either the R-134a or variable orifice tube.
 






so is the Ester 100 correct oil?

I am using a used compressor
 






There's no such thing as Ester 100 oil (although the viscosity is close to 100), there's PAG-100 and PAG-46, and regular ol' ester oil.

What vehicle did the compressor come out of? If it was a 94 or later it probably used PAG-46 and you can use that in your system if you are using all new stuff otherwise.

While both lubricants are used with R-134a, Ester is believed to be better for Retrofit systems because they are much less hygroscopic, which means that they don't absorb as much water from the atmosphere as PAG Oils do. This moisture can create problems in a vehicle's A/C system. Ester is also a truly Universal lubricant which has a Single Viscosity. PAG Oils come in a variety of viscosities which must be matched to the vehicle. GM vehicles use a high viscosity (150) PAG Oil, and non-GM vehicles use a low viscosity (46) PAG Oil. You cannot use a 100 viscosity PAG Oil as a "1 size fits all" universal lubricant. Ester Oil, however, is truly universal and will lubricate properly regardless of viscosity. PAG is a better oil, but it makes a corrosive mixture if mixed with any remaining chlorine in the system left over by the R12. When you retrofit, if there's any mineral oil left in the system there could be some chlorine trapped in it. POE (ester) oil can mix with the mineral oil, but not the PAG.

If you re-use the evaporator or lines from the system and it has black death, it doesn't matter what oil you use, it's going to spread the black death throughout the new stuff, you can't clean black death out of anything.
 






Ok thasnks for the explanation... I guess I will use either the ester or PAG 46.

Is the variable orifice tube worth the extra money? they are about $30 compared to $2 for the regular.
 






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