I just completed swapping out the A/C compressor on my 2000 SR5. I'm pretty sure it was the original stock compressor. It seized up and broke the belt last fall, and with summer coming on I figured I should finally fix it.

The Denso replacement I used has instructions indicating you should empty the oil from the new compressor into a measuring cup, empty the oil from the old compressor into a measuring cup, and make sure the amount you return to the new compressor matches the amount that was in the old compressor.

I did so. The new compressor had about 2 fl. ounces. The old compressor was bone dry. Not a single drop of oil.

I figure this is probably why it died! I returned the full 2 fl. ounces to the new compressor, and installed it.

I've seen threads indicating the oil volume for our trucks is 1.4 ounces, but I was reluctant to short change the thing given my ignorance of how this works. So I just went with what the Denso compressor shipped with.

Questions:
1. Was that the right thing to do?
2. Does the total lack of lubricating oil in the old compressor indicate some other problem I should be concerned about?
3. Is checking the amount of oil in an A/C compressor part of some routine maintenance of which I was ignorant? Seems like the only way to do it would be to remove the compressor completely from the engine, which is a bit of a pain in the ass, requiring evacuating the A/C system, etc.

Your questions,
1. Yes you did the right thing.
2. Old systems fail various ways, compressor a norm, the filter/dryer 200k+ mi
can and did screw up my system, chicken before egg - egg before chicken kinda thing.
You changed original Comp did you change original Filter/dryer? You should.
3. No, checking Comp oil is not a routine maint item. Requires attention when replacing components.

You DiY'ng it? FSM sec AC-1 good place to fill in the gaps on system.

You really should blow out all the lines with compressed air and a cleaner. That grenade’d compressor may have blown debris everywhere in the system.

You vacuumed it out?


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Correct, if you want a one n done repair on this you have to do the right chit in sequence.
Or it a crap shoot, Comp & Drier two pieces of puzzle that can fail n put debre in system you may get to replace it all.
You gotta do the investigative stuff not wanting to shoot own foot.
OP didn't mention if charge was lost for 6+ months, if so that definitely new drier.
You pull vacuum like you should your pulling 90% of oil out of system, you need to add oil amount for whole system.
OP, pull a vacuum two 12oz cans/24oz can of freon see what happens.

you are definitely not pulling out 90% of oil out of the system because you vacuum it.

You have to recover it slowly then you might lose less than an ounce. Vacuuming won't take much out either. I'd know because the oil goes into my vacuum pump oil and raise its level accordingly. It's a negligible quantity if done well.

If you are sure your system is empty, your new compressor should come with proper amount of oil, then add the amount of oil for dryer/condensor and evaporator, which should be stated in the shop manual. If I replace a compressor and condensor, I'll add the condensor and dryer amount stated in the shop manual, and no oil for the compressor if it comes with oil (I don't think I ever bought an A/c compressor that didn'T come pre-filled)

Also, if you want to do the job well, think about going with the denso. I replaced mine in 2016 with oem denso from Rock Auto and it still is going strong, as cold as ever, didn't even need a fill-up since, but don't forget to clean your evaporator.

I still kick myself in the butt for another situation where I had access to OEM denso and went with a crappy jobber. Meaning I paid twice and worked twice.

I always add dye to my system. That takes the guess work out of my leaks.

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You Vacuum it to pull 90% out, "/Hg for a given time, gives you the best shot one n done repair
with partial parts change out. Old oil is bad oil, it easier to calculate amount of oil to use,
too much not enough oil is a thing.
Pump catches part rest is vapor/saturated vapor that you wipe off atmospheric vent, fog at vent is oil hand over vent?

Dye/UV good stuff. UV Shows stuff, all kinds of stuff.