Paul Waterloo

I am starting a new thread on the AC compressor replacement, but here is the run up to the removal of the old one:

https://rennlist.com/forums/968-foru...ly-pan-on.html

When I removed the compressor from the car, I did not detach the AC lines from it before unbolting it, not a good idea. You'll want to remove the refrigerant, then unbolt the high and low pressure line from the unit, then the tensioner and two mounting bolts and drop it down. See pictures further down the post when things were going back in.

So here is the broken bolt in the ear, not the greatest pictures, but you get the idea.





I tried to drill it out but couldn't.



This is as far as I got....



Then I broke the ear off.....if you look at the machine surface where it goes into the mount, it was getting hosed up and I kind of wanted to replace it at that point anyway.

So I bought a rebuilt unit from Stockwiseauto.com. I actually bought a 471-0127, which is what I took off (two owners ago it was replaced) but their website says a 471-0128 is the correct one. I'm not too worried. It was $385 shipped.

Then I read about guys here that replaced the rebuilt compressor many times due to issues....and another place on ebay that I was considering had emailed me back stating they rebuild them in house.

However, when I got it I was happy to find out that it appears to be factory rebuilt by Denso. It looks great, has some simple instructions.

You can see that I need to swap the top fitting on my old compressor onto the unit, so I need O-rings for that. I might get to replacement tomorrow....thinking I will then bring it in to have it evacuated and charged. That's another $125.

Will take some more pictures as I go along. Thinking about draining the oil out of the unit to ensure it has the proper amount, but I think it already does.

Old Unit:



New Unit:

thomasmryan

Nice and pretty. Put a little never-seize on the treaded tab/ear but it must have been over torqued at some point? Have you ever tried pb blaster? I noticed your can of WD. PB is pretty awesome stuff for rusted item.....I am taking apart a 50 year old VW 1500 and lots of rusted things. Not one stripped bolt yet.

Weigh you new and old compressor. That will give you an idea of how much oil to add. It is also wise to replace the dryer when the system has been opened. Again, weigh old and new for the oil you are removing with the old parts. I just changed the core, expansion valve and the dryer in a w140 and my kid got at gassed for me for 40 bucks. The repair guy had some 30k recovery type machine that calculated the oil left in the 134. It makes the dash sweat it is so damn cold)))

griffiths

Paul,

Good idea for a thread.

When you have a broken bolt you can use an "easy out" to remove the broken bolt.

You might want to show removal of the 4 6mm allen head bolts from the old comperssor holding down the manifolds, cleaning of the manifolds, replacement of the 4 manifold o-rings, dumping of the factory oil in the new compressor, explain how you can either put new oil (ester or pag, you need to determine) in the compressor before you bolt it back on or discuss how the shop will inject it, replacing your drier, maybe replacing all the o-rings for good measure, inspecting the comp to cond hose and cond to drier hoses as they typically fail by now, checking drive belt... etc.

Paul Waterloo

Sounds good....the system was working perfectly when I took it apart so I'm not replacing anything but the compressor.....but will capture some or all of those items that you mention.

MB968

Glad to see the new compressor arrived. Definitely replace the dryer while you are at it. They aren't that expensive. And once they've been exposed to the air for a while, they could loose their effectiveness.

Paul Waterloo

So the new compressor is in, I have made one trip to the ER during installation due to falling compressors onto my face, had my stiches on my face removed this morning, and then had the system evacuated and recharged. It works like a champ and I don't think anyone will think much of my face in a month or so, will just have a little more character.

So here are the details:

Old vs. new compressor. When you get the new one, you have to change the car specific manifold over to it. It just comes with cover plates. The new compressor comes filled with oil, and you are supposed to measure the oil from the old compressor by draining it and then drain the new compressor and adjust the fill to match the old one. This I did not do, I lost an ounce or two during installation, but it has in it, what it came with, minus an ounce or two.

NOTE: DO NOT turn the compressor with the covers off, it will pump the oil right out. You can turn the belt drive part because the clutch isn't picked up, but once the shaft of the compressor is turned, oil will pump out.



Remove the manifold from the old compressor:



Here are the O-rings, the black ones come with the compressor, one of each other type are required for the low and high pressure hose connections to the compressor. Note new part number on the purple o-ring.



Install manifold with new O-rings using a torque wrench, as I recall it was 18 ft-lbs.





I changed the lugs from an uninsulated lug to an insulated lug.







For the back side mounting bolt (the aft one), I used a longer bolt so that it comes out of compressor mounting ear. If the bolt ever breaks again, I will be able to get to it.

Paul Waterloo

Here are the new O-rings installed:





You are going to want to mount the compressor on the car before installing the refrigeration lines. The first thing you will need to do is to tap the sleeve back a little bit for the aft smaller bolt. I did this by using a smaller ball peen hammer turned 90 degrees so it fits were the compressor is and just tapped the sleeve a few times, it moved back. Test fit the compressor so you make sure it will clear the mounts.



GET A FRIEND to start the bolts from the top while you bench press the compressor in. I did this myself and after the fourth try, it feel and hit me in the face. Here I am at the ER before I got my stiches:



Then after I got back from the ER:



My neighbor helped start the bolts....took all of four seconds.

Once you have the compressor in, snug up both the front and rear bolts (especially the rear) so the sleeves seat in the holes, as you tapped the sleeve back to create clearance for the installation. Then back off the mounting bolts 1/4 turn so it can pivot for the belt tensioning procedure.

Install the new belt, install the tensioner, and then hand tighten the tensioner and finish with a few turns of the wrench to get a nice tight belt. I would turn the bottom part of the belt (longest run between pulleys) in the middle and see how hard it is to turn it 90 degrees with my fingers. I left it where I could basically get it just a little less than 90 degrees with my fingers. Tighten the tensioner bolts, then tighten the forward and aft compressor mounting bolts.

It should be noted that I added some spacer washers on the tensioner to get a nice straight run from the compressor to the other mounting point to minimize any side forces on it.



You will have to remove the power steering pump belt for this procedure to get to the ribbed belt, it's the same as the compressor, first loosen the two 13 mm nuts on the forward and aft part of the main mount so it can pivot, then loosen the tensioner and take the tension off.

My tensioner had stripped nuts, so I bought this one from ebay, worked great:



In the end, I installed a new dryer, the following pictures are pretty self explanatory:













The correct part number for the two O-rings that need to be replaced is 909-707-262-40. The following picture shows the O-rings that I bought (which I thought were correct, but were wrong based on my view of which one it is, it's number 60 on the exploded diagram).....the AC shop replaced them with one the correct size. Correct size is the dark green one.



I then brought it to an AC shop, had it evacuated and charged. Works AWESOME again.

MB968

Nice pics and writeup on how to do this. Can we eliminate the one step and still get cold air. I prefer to avoid ER. Cheers, Joe

docmirror

So, here's some unrequested advice. Since you changed the dryer, and have a new comp, it's a very good idea to pump down the system and let it stay pumped down for a few hours. Opening the AC system in summer lets in quite a bit of water vapor, and it's best to get all that H2O vapor, and also air out of the system before charging.

An AC shop will pull a vac, but they only leave it down for about 30 minutes cuz they have cars to get out. It's better to have it pumped down for a while, because getting all the air out takes a bit of time. Next pressurize with N2 for a few hours as well. Let it sit on a cardinal pressure and check it so that you know you aren't losing pressure. This is really important on a R-12 system because of the cost of R-12. Once you're sure you aren't losing pressure, evac again and then charge with the R-12 juice.

That back bolt is going to give your trouble in time. They all back out due to the jerking of the comp as the clutch picks and releases. I hogged out the hole, put a bigger thread in there on the ear, then I nutted it on the inside with a custom ground nut. It's a weak design and it will come lose eventually.

Have fun, it takes a good 6 hours to get the system vac, pressure, vac, charged if you do it right. Most places don't bother with enough vac or pressure test.

griffiths

Wow Paul, looks like a Denso caught you with a right jab when you dropped your glove; your lucky, you could be wearing an eye patch .

The reason we go through multiple evacuations is two fold: on long systems (911/930) is because it is possible to pull a vacuum and have residual moisture in the system turn to ice before it vapors off to a gas, and on systems that are not virgins (having old components that have not been liquid flushed) if you are retrofitting from R12 or R134a it is possible to have some previous refrigerant gas trapped in the old refrigerant oil). Using refrigerant as the purge gas is easier than adapting a nitrogen cylinder for the average DIY, but if you got an inert gas like nitrogen it will work as well.

dougs968

Paul, this thread is going to come in handy pretty soon. My 92 has been without AC since I got it. I believe the compressor is toast. The reason I think that is when I push in the AC button to energize the compressor it locks up. Horrible belt squeal until it powers down. That takes a few seconds to do even after its switched off.

I would like to stick with R12 if I can find it. Otherwise some other refrigerant. It gets pretty darn hot here in North Texas.

Doc, those are great ideas! I can do the whole mod easy as pie. Extended draw down of the system might take a little doing. I need to check with a couple local to me guys.

Paul, ouch! I try not to drop things on my head but sometimes it happens. My worst was the drive shaft on my 3/4 ton Dodge. When I pulled the stub end out by the carrier bearing, it flopped out and hit me in the mouth. Thought I broke teeth for sure, but only bit completely through the upper lip.

Jay Wellwood

Shameless plug for Griffiths items.

Worked great on my Black on Black 928S4 and on my 968.