[jschiller]

I have posted this question elsewhere but haven't gotten a workable response yet so I thought the experts here might have a solution.

I have an '89 S4. What is the secret to dropping the AC compressor? Does it have to come out with the console attached?
I've removed every bolt I can reach except this one:


I believe it is holding the top compressor lug to the console. It is lower than the flange on the pulley so I can't get a tool on it except a crowsfoot and that just slips off due to the angle. Even my Mountain wrench is too deep to fit in small gap between the pulley and the bolt head.

So far my options are remove the clutch and pulley in place to reach the bolt or grind a divot in the flange so I can get a socket wrench straight on. Or is there another answer? If the compressor has to come out with the console attached, how is it removed?

Am I going about this all wrong?

[worf]

Before you go further:

- make sure you've disconnected and unrouted the lead from the front main harness to the compressor clutch (can't tell from your picture)
- if you aren't going to remove the compressor immediately then make sure you have something to slide under and support it once you've removed it from the console.

Now... that 17mm-head bolt. Here's what I do:
- once the rear bolt is out or barely engaged and the tension bracket is disconnected
- break it loose with angled box-end wrench. I have a not-as-thick-as-the-Mountain extra-long ratcheting flex-head. You can do it with a typical bent-end combo wrench too.
- from underneath, use the right hand to "wiggle" the compressor to take the weight off the bolt and use a stubby open-end 17mm in left hand to turn the bolt until fingers can rotate the bolt. If the compressor has been on forever, then it probably won't "wiggle" but the bolt shouldn't be hard to turn out by fingers once it's loose.

Things not to do:
- do not use a closed-end wrench once the bolt is broken loose. You'll end up trapping the wrench with the pulley.
- do not forget to unroute the clutch lead.
- do not drop the compressor on your face

Last:
- that bolt is almost always loose. No one - it seems - goes to the trouble of actually tightening it except Hans at the factory and a few OCD types like me.
- every once in a while the threads are screwed up. That's when the the stubby 17mm comes in real handy - when you have to turn that bolt out one flat at a time.

[jschiller]

Now... that 17mm-head bolt. Here's what I do:
- once the rear bolt is out or barely engaged and the tension bracket is disconnected
- break it loose with angled box-end wrench. I have a not-as-thick-as-the-Mountain extra-long ratcheting flex-head. You can do it with a typical bent-end combo wrench too.
- from underneath, use the right hand to "wiggle" the compressor to take the weight off the bolt and use a stubby open-end 17mm in left hand to turn the bolt until fingers can rotate the bolt. If the compressor has been on forever, then it probably won't "wiggle" but the bolt shouldn't be hard to turn out by fingers once it's loose.

Thanks for the tips, just what I need from someone who has BTDT.

I think I might have to sacrifice the shoulder on my Mountain wrench by grinding it off so it will slip into the small gap (hopefully the head it not too big to engage the bolt in-situ) if I can't locate a suitable box wrench. As I understand you, once I have cracked the bolt loose, there will be sufficient room to back the bolt out far enough to clear the lug threads even though the bolt may still be captured by the pulley flange if I can't fully withdraw it. PET says the bolt is 33mm long and I don't think there's that much clearance. I'll just have to try it. Wish me luck!

[worf]

I think I might have to sacrifice the shoulder on my Mountain wrench by grinding it off so it will slip into the small gap

I used a run-of-the-mill Craftsman bent-end combo wrench to break loose that bolt for years before I got a longer one. It's a bit futzy, but I wouldn't spend time and sacrifice a perfectly good Mountain. Surely you have some other 17mm wrenches.

(hopefully the head it not too big to engage the bolt in-situ) if I can't locate a suitable box wrench. As I understand you, once I have cracked the bolt loose, there will be sufficient room to back the bolt out far enough to clear the lug threads even though the bolt may still be captured by the pulley flange if I can't fully withdraw it. PET says the bolt is 33mm long and I don't think there's that much clearance. I'll just have to try it. Wish me luck!

Yes. There's enough clearance for the *bolt* just not enough clearance for a wrench over the bolt.

[worf]

[jschiller]

Took a little doing but Worf's statement that they are not usually re-tightened snuggly suggested another approach. I used a somewhat disposable HF 17mm box wrench with a 3 foot cheater bar slipped over the end. I wedged a looong pry bar between the bolt head and the pulley to keep the wrench on the bolt (it wants to rotate off the bolt head due to the angle) and pulled both like hell. It finally cracked and I was able to back it out.

Now to document the hose clockings and I can pull it out of there.

Onward and upward.

Thanks Worf

[jschiller]

Another thought. What to do with it; drain the oil and flush, clean it up and put it back with new o-rings, or buy a reman from somewhere and be done with it. This one has +80,000 i on it. I don't want to put $500 into something that ain't broke but I sure don't want to do this any anytime soon. I'm in Florida so it will be getting a lot of use.

[worf]

Another thought. What to do with it; drain the oil and flush, clean it up and put it back with new o-rings, or buy a reman from somewhere and be done with it. This one has +80,000 i on it. I don't want to put $500 into something that ain't broke but I sure don't want to do this any anytime soon. I'm in Florida so it will be getting a lot of use.

There’s no way that compressor isn’t leaking at every seal. If you have a way to make it squeaky clean inside and out you can replace the nose and case seals. Or you can just expect to need to recharge more often.

At this point I always buy the new/reman from the ND store for ~$400. It’s not worth my time or warranty exposure to do anything else.

The other thing is hoses. The original hoses aren’t r134a barrier-type hoses. Is that why you’re worried about the clocking? Because you’re going to get them rebuilt?

[jschiller]

There’s no way that compressor isn’t leaking at every seal. If you have a way to make it squeaky clean inside and out you can replace the nose and case seals. Or you can just expect to need to recharge more often.

OK, I'm convinced. I can clean it and put new seals in it but I wouldn't ever trust it to last. I'll get a reman unit. I'll put up with the current hoses and just pop in a can of R134a every few years. Getting the hoses rebuilt locally (and accurately) might be too much of a challenge.

[SeanR]

Like Worf, I just get new ones from Roger and put them on. I have rebuilt a number of them and I'd say it was 50% good and the rest we don't talk about.

[worf]

Curious as to where you were able to get a new compressor hose set for $300?

Oh. Nevermind. I see that Griffith's has 6E171 barrier hoses for $300 a set.

Be glad you don't have the 10PA20 or you'd be rebuilding your own.

[worf]

Like Worf, I just get new ones from Roger and put them on. I have rebuilt a number of them and I'd say it was 50% good and the rest we don't talk about.

LoL. Yeah. Just getting them clean enough to work on was too much effort.

[jschiller]

So the new compressor arrived today and I have some new questions.

It's a reman from DENSO so I am fairly certain it has mineral oil in it as that's the original spec for R12. I know to pour it out and measure the amount so I can refill with the same amount of ester or PAG or whatever I decide to replace it with. The first question is how then to flush it. I have AC flush and I can pressure flush it on my homemade flush setup but is that sufficient? I can dial up the flush pressure to any reasonable amount (50psi, or so using shop air). Will the flush circulate throughout or will there be oil I can't flush out so will mix with the new oil?

Then the big question...which oil? POE (ester) is safest as it will mix with any residual mineral oil in the system. Double end capped PAG is the best performing if there is no mineral oil left anywhere.

Should I rely on my home flush skills and go with the PAG, or fall back to ester for safety?

[SeanR]

I keep Ester/PAG 46 and Mineral oils on hand and if I'm doing a change from r-12 to 134a with all new components then I'll do a complete flush and use PAG. If it's a partial like you are, I'll use Ester after doing a flush, with the caveat that I can't warranty it for any length of time, but for the cost compared to full rebuilds, it has worked well for me. For the R-12 cars who want to keep it stock, Mineral.

[worf]

Double end-capped PAG is compatible with mineral oil. And I have used it on 134a systems that I have flushed.

I have never, ever used "plain" PAG oil on a 928. I do not consider my flushing mechanism sophisticated enough to remove all traces of mineral oil.

So, for the most part I use Ester oil in 134a systems.

[worf]

If it's a partial like you are, I'll use Ester after doing a flush, with the caveat that I can't warranty it for any length of time,

So... this makes me curious. What's so bad about Ester relative to PAG except for PAG's superior moisture absorption characteristics?

[SeanR]

If it's a partial like you are, I'll use Ester after doing a flush, with the caveat that I can't warranty it for any length of time,

So... this makes me curious. What's so bad about Ester relative to PAG except for PAG's superior moisture absorption characteristics?

Just covering my own ass after advising I need to to a total flush and replace all components and they choose not to.