Looking for a little help from the community on getting my AC to work.

In December I retrofitted from R12 to R134 by accomplishing the following:
1. Flushing all hoses and evaporator
2. Replacing the compressor, accumulator, orifice tube, and O-rings
3. Placed compressor on it's nose for over 3 minutes (manufacturer recommended to lube seal)
4. Rotated clutch more than 10 times

After about a month the compressor failed (had oil & dye on the bottom). Checked orifice tube and there were no metal shards on it.

Then I redid the system again.
1. Replaced compressor, accumulator, orifice tube, high & low pressure switches, and the condenser
2. Placed compressor on it's nose for over 3 minutes (manufacturer recommended to lube seal)
3. Rotated clutch more than 10 times

The shop that recharged the system did a leak test and pulled vacuum for 45 minutes prior to charging each time.
New compressor failed again after less than 150 miles. I noticed on the day that it started failing, each time I turned the AC on it initially really brought the RPMs down but then recovered and ran normally.

Utilizing a dye testing light there was no evidence of leaking at any of the connections.

I know it's a loaded question but what could I be doing wrong?

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1986 Fiero GT
Muncie 4-speed
2.8L V6

what oil are you using and how much?

[This message has been edited by skywurz (edited 05-07-2021).]

Per 4 Seasons I used PAG150. 8 ounces total. The AC compressor was pre-filled with 3 ounces and I added 1 to it. Added 2 ounces each to accumulator and condenser.

You flush the Evap?
How?
Because "Flushing" that is often a big problem and still leave crap there too. Plus If whatever flush media doesn't dry out before recharge then the media can wreck the compressor.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

Thanks Ogre!

When doing my research on changing out the system I found a thread on that but it was after I'd already done it. That was on my first go round and I left it open for a week while blowing compressed air through it multiple times per day until nothing came out. Didn't flush the system on the 2nd try.

I guess a better question now is . . . how should I proceed on the 3rd try to have a successful repair?

quote Originally posted by Ronbo4786: Thanks Ogre! When doing my research on changing out the system I found a thread on that but it was after I'd already done it. That was on my first go round and I left it open for a week while blowing compressed air through it multiple times per day until nothing came out. Didn't flush the system on the 2nd try. I guess a better question now is . . . how should I proceed on the 3rd try to have a successful repair?

When flushing, you should use plenty of flushing agent.a flush kit is needed to do it properly. Just compressed air won't cut it.

I am not a big fan of Four Seasons rebuilt AC compressors. They sometimes fail. Also not big on using PAG oil except in completely clean systems or systems that originally used it. . If there is any residual 525 mineral oil in the system the PAG will not mix with it and oil function will be poor. I always use Ester oil on old R-12 systems. Overcharging and/or a clogged condenser can cause a failure. Did you check that the condenser was free clear and not obstructed?

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Thanks for the inputs.

I used the flush kit from Auto Zone with a proper flushing liquid.

The second time I replaced the condenser with a brand new one. Both compressors were new not remanufactured.

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1986 Fiero GT
Muncie 4-speed
2.8L V6

I just had my compressor replaced with a new Four Seasons compressor, dryer and metering tube. Flushed and used ester oil. The compressor is noisy as all getout.

quote Originally posted by fierofool: I just had my compressor replaced with a new Four Seasons compressor, dryer and metering tube. Flushed and used ester oil. The compressor is noisy as all getout.

Just researched where all the brands of new A/C compressors are manufactured and it looks like they are ALL Made in China. My experiences with Chinese parts is that the quality is all over the place. They can be good but they can be very bad. Sometimes a noisy compressor is caused by the clutch that may not be adjusted properly or uses a low quality ball bearing. When you replaced the compressor did you replace the accumulator, orifice tube and insure that the condenser was not blocked with debris?

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Yes. This was a complete new KIT that included everything except the flush. Done with commercial AC equipment by a licensed tech. We used ester oil instead of the PAG oil that came in the kit. My system has been 134a for about 10 years, so mineral oil wasn't a concern.

quote Originally posted by Ronbo4786: Per 4 Seasons I used PAG150. 8 ounces total. The AC compressor was pre-filled with 3 ounces and I added 1 to it. Added 2 ounces each to accumulator and condenser.

You add oil Only to the compressor and Acc/drier.

adding a slug of Oil in condenser can slug to Orifice causing flow problems etc.
Many add oil to evap but then oil mostly just sits in the bottom of evap.

Yes, Most PAG hate R12 oil in the system anywhere.
Even if you flush before replacing a lot of parts, you never get rid of old oil.

Plus If you let system Or Oil "Bottle" open to air for hours to days... Many Refer oils draw water from air like Brake Fluid or worse. You likely heard only use New Brake Fluid from Sealed "bottles..." Same is true for most Refer Oils. A capped "bottle" after a seal is broken can let a lot of water in them in just a few hours to days depending on weather, more specific the Relative Humidity, and how good is the cap seal.

Drier pillow(s) in Acc/drier can do same thing. Can take hours to days to pull out water from a system.
Worse, Running a vac pump 24/7 often only wears out the pump but many shops to that anyway. Most Shops need Pump rebuild many years ago because of this. And because of pump wear, the pumps can't pull down the system to pull out the water.
Is hard to pull out water from AC even w/ "lab pumps" that are only started after the "normal" pumps pull down the max vac they can.

Side note: This is why many "leak sealers" fail and worse often plug the whole system. Many that claim to seal holes in metal use moisture to activate it but most systems that leak "dead" have water all over the place. Worse, many have "fine print" only works w/ very small holes that tries to keep vacuum for awhile. Not holes that loose vacuum in seconds to minutes after pump is off.