Keywords: compressorworks compressor works R4 air conditioning rear seal W123 1983 300CD 300D 300TD Delco Harrison GM
I’m re-habbing my air conditioning and replacing the compressor. This should be an easy job: one belt, six bolts, available parts. But no……
Warning/disclaimer: Venting or discharging your refrigerant (R12 or R-134a) into the atmosphere is illegal (and messy, and dangerous). Get your system evacuated, then work on it.
Wear goggles – there’s no end of greasy crud under your car.
Try to wear gloves – I did sometimes, but the darn Texas summer heat made that more miserable than greasy dirty hands
I’m removing a Harrison HR100T compressor and replacing it with a CompressorWorks 620230 unit. Both are R4, neither are M-B OEM.
I’ll skip the diagnostics that led me to decide to replace it. (highlights: leak from rear seal, probably bad clutch bearing, possible bad front shaft seal and maybe bearing, already evac’d system once…)
Get your parts:

Compressor – bought from a major chain for less than $200. CompressorWorks R4 compressors are made in Dallas and are reputed to be the source for re-branded units for Delco and others. That’s rumor I read on the Internet, but if you’re price shopping, you may want to ask the source before paying extra . http://www.compressorworks.com/

Belts – I went ahead and got all four: 2 x alternator belts, P/S belt, compressor belt. You don’t HAVE to replace the belt, but mine were old from the PO, had some wear and cracks and I figured I’m halfway there with the P/S pump and A/C belt out, so I’ll do ‘em all. It’s probably a good idea to buy alternator belts in pairs, from the same production run. That way they’re no-kidding the same size.

Oil – This is not a trivial decision. Are you going R12, R-134a, or just not sure? If R12, get mineral oil, if 134a, go for a 150 viscosity double end capped PAG, if you’re not sure go with Ester. I’m going 134a, so I used DEC PAG. What is “double end capped”? I don’t know, since I’m not a petro-chemical engineer but it refers to the oil molecule and it is resistant to absorbing moisture. See here for a science experiment with test tubes, graduated cylinders, and words like “polymerize”: http://www.autoacforum.com/messageview.cfm?catid=20&threadid=17571

Seals – this was the bane of the install. More later, but look here to see the rainbow of variety of sealing washers for GM compressors. For this specific install I needed the yellow one and the green one. Of course, I didn’t have them or know that. The major chain compressor did not come with them. The pic for the compressor at the AllParts site shows them, too. Do not assume you can re-use your old ones. http://autoacrepairs.com/sealing_washers.htm

Receiver/dryer – I won’t cover it in this install, but if you’re opening up the system you may as well replace this. They’re listed for some astronomical price, but you can buy Behr brand for less than $20 online.

Get your tools, at a minimum:

Phillips screw driver, 19 mm socket and wrench, 15 mm, 13 mm,10 mm, various adapters and extensions and drives. One of the most useful combos I found was using 1/4 inch drive hinged ratchet with a 3/8 adapter and the 19 mm socket. It made for faster turning after the bolts were loose. I also got the loaner clutch wrench from AutoZone.

1) Wash and degrease as much as you can. You’ve probably got leaking oil line residue, leaking P/S pump residue, maybe leaking compressor oil residue and road grit. It’s messy under there.
2) Get the system evacuated.
3) Loosen the P/S pump. There’s no mystery here, but here are some pics. I removed mine since I also discovered it was leaking from the rear O-rings (and yes, I’ve got a kick-butt DIY on rebuilding those…)
4) My nuts/bolts were all 13 mm. Watch out when loosening the lower inboard because there’s another 13mm bolt back there maybe an inch higher or lower. You may think you’ve got it, but you loosened something else.
5) The upper inboard is the pivot, lower inboard and lower outboard are sliders (note the lower inboard has the least travel) and the upper outboard is the adjuster. This “nut” that mates into the P/S pump body is just plastic, so you may want to think about that the next time you’re torquing down on that guy.
6) Loosen the P/S pump and remove the belt.

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7) Unplug the compressor. Take a look at your connections. I think the PO did not have the connection on tight which may have led to an intermittent connection and a slipping clutch. The connectors should be a “spring fit”. The auto-focus wasn’t so great, but one fitting was shiny/worn on the front and the other on the back. The plastic housing was also worn through, so I think the electrical connection was made between the spade fitting and the plastic, not by the actual spade fitting. These were also saturated with old oil, so I cleaned them to get a good electrical connection later. If you remove the Philips screw near the oil lines you have more room.
8)Start loosening and removing bolts on the compressor. I found that moving the compressor was easier after I disconnected the manifold. You did evacuate the system, right? If not, you’re in trouble now. There’s a 13 mm nut/bolt that hold the manifold to the compressor via a bracket and a 15 mm between the two ports. Before you remove that, take a look at the small gap (<1 mm or so) between the manifold plate and the compressor body. That’s what you’re looking for at the end of the job (note: I have no experience with O-ring style R4 compressors, you probably don’t want a gap there if you have an O-ring.)
9) As you loosen the manifold, bright green oil (if it’s a 134a system with UV dye) will leak out. You may want to capture the oil to measure how much is coming out. Since I was going to flush my whole system, I didn’t bother measuring, but I did have a catchment pan. Wear goggles.
10) The 15 mm is sort of a hassle. I couldn’t fit a socket in there and I don’t think there’s room for a ratcheting box wrench. Tough it out.
11) A sealing washer MAY fall out as you really loosen the manifold.
12) There are three 19 mm bolts that go from rear-to-front and one 10 mm adjuster bolt. The pattern is similar to the P/S pump: counter-clockwise from top – pivot, slider, slider, adjuster. I needed to use a variety of sockets and extensions. A hinged 19 mm box end would have been primo. I don’t have one.
13) When the bolts are loose, you can remove the belts. If you’re going to do the alternator belts, now’s the time. I’m not covering that this DIY, but don’t dork up your adjusting bolt – it’s a $70 part. Loosen ALL the nuts and bolts, then turn that adjuster. Put on the new belts and get back to the compressor.
14) As you remove the mounting bolts, the spacers will fall out and roll away or hit you in the face. Wear goggles.
15) Remove the old compressor.

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16) The pic is from floor up with the spacers back in place. I’ve got a crappy auto-focus, but on the left you see the middle-sized spacer and the adjuster banjo bolt that goes up to the 10 mm nut on the top. Slightly to the right and a bit lower in the pic is the pivot bolt. Top center in the pic is the manifold, with a sealing washer still stuck to it. Just to the right of that, and behind it in depth of field, you see the long bolt and tube with a thick washer. That bolt goes through the mounting bracket to the thick spacer. This is more/less your pre-assembly set up.
17) Before you put your new compressor in, you should do a few things. You should inspect your lines for any signs of “black death.” Do a search on Google and see what I mean. If you’ve got “black death” then you need to flush the heck out of your system or you’ll be doing this job again soon.
18) If no black death or other crud, then carry on and break the seals on that shiny new compressor. Here is where I screwed up and it cost me time and effort. Dry fit your sealing washers before you do anything else. I ass-umed R4 compressors were all the same. I knew I had a leaking sealing washer, so I bought two new ones just like my old ones. The compressor didn’t come with any others.

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19) The Harrison HR100T has two recesses of equal size and equal depth milled into the back – this fooled me into thinking I was prepared. The CompressorWorks has one large shallow recess and one smaller deeper one. Look here for the variety. http://autoacrepairs.com/sealing_washers.htm You may find different AC and parts supply sources that say you need two black ones for your M-B. They may be right for a different model compressor, but not if you’re using the same model CompressorWorks I did.
20) What you’re looking for is the washers to stick up just above the surface of the compressor body. On my old Harrison, the recesses were about 2 mm and the washers are about 3. On the CompressorWorks, the deep one is a little over 4 and the shallow a little over 2. The 15 mm bolt on the manifold will sandwich the rubber sealing faces against the compressor body for a tight fit. If the manifold fits against the body of the compressor, or it’s uneven, then it’ll leak. (Note: this is not an O-ring install).
21) Dry fit all your bolts: the short 15 mm for the manifold and the long ones to bolt up the compressor. First, it’ll be peace of mind that when you’re installing the compressor and the bolts aren’t moving and you’re sure you’re cross-threading a metric thread into an SAE hole that you aren’t actually doing that and they DO fit. Next you’ll see how much dirt and crud are in the threads and how gritty it is and you’ll be inspired to get the old toothbrush out and clean them. You’ll think you’re really clever when the bolts go in easier later.
22) Once you’re sure you’ve got the right parts, you can put oil in the compressor. You MUST do this. I’ve read some compressors come pre-oiled. Mine didn’t, and it’s just as well since I wanted the DEC PAG oil in there. The exact capacity is not entirely clear. The FSM section 83-520 has specific quantities to add depending on what you’re doing and how much oil you’ve removed. The compressor re-install section, 83-522, says a total capacity of 170 cc, or about 6 ounces. Your call. Too little oil is bad, too much is very bad.
23) CompressorWork’s installation instructions http://www.compressorworks.com/InstructionSheets/Install%20Instr%20-%20AC%20Compressors.pdf say to add 2-3 oz to the suction side. This is consistent with pretty much everything else I’ve read. Then they say to turn the compressor at least 10 times. Now you need the loaner clutch wrench from AutoZone.

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24) The clutch wrench has three adjustable pins that mate up to holes in the clutch. I adjusted them when it was clutch-up, then turned the whole thing upside down.
25) I put one-third-ish of the 8 oz bottle into the suction port while holding the wrench stable and rotating the compressor body.
26) Some of this oil will run out when you try to mount the compressor. To minimize this, I loosely replaced the rubber seal in the ports.
27) You can lube and place the green sealing washer over the manifold now.
28) Reinstalling is somewhat of a hassle, since you’re trying to align three holes with spacers on two of them, the oil is starting to drip, the compressor is heavy and awkward for one hand while you’re trying to get the other hand with wrench in place.
29) The technique that worked for me was to start with the adjuster screw bolt. It seemed to line up easiest. At this point you may want to consider putting the belt on since you’ll have the most freedom of motion. I had fitment issues, see below. The downside of doing the belt now is that you’ll have no guarantee you can get it off without the manifold attached, just in case you have the wrong belt or something.
30) I used the manifold bolt to pull the manifold closer, removed the rubber seal, put a jar to catch the dripping oil, placed the yellow sealing washer in place and struggled getting the 15 mm bolt in place. The hoses are stiff, but I found that if you push up on the manifold the hole line up and you get the bolt to screw in. Pushing up on the manifold was the only thing that worked for me. For a while I was sure the bolt didn’t fit and I was stripping the hole, so I removed everything to check. It fit fine. I didn’t feel clever. End torque on this bolt is 50 Nm, I think. I can’t get a socket in there, so my calibrated 15 mm Craftsman box end has to do.

31) I put the other bolts in place. I didn’t have too much trouble getting them aligned and in. I left them very loose.
32) I was puzzled when I could not get enough slack to put the belt on. I could see I had plenty of travel left, but the compressor wouldn’t move. I discovered the manifold nut was now hung up on the lower oil cooler line. Since the manifold is connected to the compressor, it has to move, you can’t just loosen the small connecting bolt to the mounting bolt.

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33) I loosened the oil cooler line brackets (10 mm sockets) and forced the nut past the cooler line in order to get enough slack to get the belt over both pulleys. Then I had to force the nut back up past the oil line in order to tighten the belt. My oil cooler line is ContiTech, but I don’t think it fits as well as the M-B stamped one I took off. I really need those 2-3 mm back.
34) When I used the tightening bolt, I did get some clearance that the nut and hardline are no longer touching, but I’m not happy with the risk to the oil line and may replace it. I am concerned about maybe having to overtighten the belt and put wear on the compressor and clutch bearings to keep the lines apart. I’ll watch it and see how it plays out.
35) In a previous junkyard expedition, I pulled off an intact plastic clip to replace my worn through one for the electrical connection. To ensure I got a tight fit on the spade connectors, I pulled the connectors all the way through the cover, then put them on individually onto each connector on the clutch, then I pushed the plastic cover into place. Don’t forget about the Phillips screw if you removed that to get cable slack.

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36) I tightened the belt, then tightened the three mounting bolts. FSM says 60 Nm for mounting bolts.
37) In the pic, you can barely see the slight gap between manifold and compressor body and a snug clean electrical connection. You can also see what I didn’t notice until very late in the repair. My manifold was repaired and rebrazed at the hose fitting. There’s a large blob of brazing material right in front of the hose. I don’t know if he hit a rock or had some other damage, but I’ve never seen it leak there, so I guess it’s tight.

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38) Install a new P/S belt, if desired. Remember about the plastic tension bolt and tighten up the other three mounting bolts. FSM says 25 Nm for 8.8 hardness and 35 for 10.9.
39) Double and triple check for misplaced tools. Do a “tool count” and put them away. Take a break, come back out and look everything over one more time.
40) Dry run your belts and other connections. Make sure the A/C is turned off so the clutch doesn’t try to engage, even though the low pressure switch should stop it.
41) Have your system vacuumed and charged (note: you should also replace the receiver dryer, but this DIY is long enough already).
42) Before you go all wild with your new in-car coolness, you should burnish your shiny new clutch. This is what Ryder says about burnishing: “Burnishing is the cycling of the clutch to allow a wearing in of the engagement surface area. The reason for burnishing a clutch is to increase the initial starting torque. Most technicians fail to follow this important procedure when replacing a compressor or clutch. An unburnished clutch can produce a low torque condition, causing the clutch to slip and thereby fail. When replacing a clutch or compressor & clutch assembly, follow this important burnishing procedure. Run the engine at 1,500 to 2,500 RPM. Using the controls on the dash, cycle the clutch ON and OFF at a rate of 10 to 15 times per minute for a total of 50 cycles minimum. This should bring the clutch up to operating torque capacity.” The Ryder page is an excellent reference with clear simple paragraphs: http://www.ryderfleetproducts.com/cgi-bin/ryderfp/technicalbulletins/acClutchfail.jsp
43) I haven’t used my system yet since I’m still waiting for a new parallel flow condenser (Yeah, thanks a lot for expediting the already two week overdue parts Arizona Mobile Air – I hope your parts are good, because your service is lacking…UPS ground on Wed and you think it’ll be here by Friday?) Assuming they ever get here, I hope to have the system evacuated, leak checked and charged soon.

Yak, Did you get the PF condenser yet?

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

No. I was on vacation. I talked to the guy who built the new hoses and he insists it was shipped but they couldn't track it. They were ready to build a new set of hoses and overnight it. Since I was gone, I said I'll wait. It didn't come in while I was gone, so now they're shipping again. It'll be here before the end of the week, I hope.

I just purchased a NEW Compressorworks R4 and was wondering how your system turned out? Thanks for your response

I've installed dozens of them. ALWAYS a happy customer with it!

if you've got any questions, just start your own thread, and I'll likely see it, and chime in with help for ya!

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

BIG thanks...will do