Which compressor?

I'm thinking about replacing my A/C compressor due to metal shavings in the line. Sometime in the near future anyway, it still works aside from the leaky seal.

Looking at Rock Auto there are quite a number of compressors available. Mine looks like the H6 or HD6 style, not the R4 one (1994)

I'm just curious if anyone has any insight or recommendations as to which one is "the most correct" and operates the best, I suppose.

New Delphi. CS0123. Also, replace the accumulator while you are at it. Four Seasons or Delco.

Any particular reason why the Delphi one is any better than the Delco or other ones? Just curious- some of them cost (way) more and it may be because they're better. Or it may be because they cost more.

Looking at the instructions it mentions turning the compressor by hand with a tool that threads into the hub or with a spanner wrench after adding oil and before installation, I hadn't expected that.

Also do I really need to change the accumulator? I changed it less than a year ago. The system has a slow leak that I think I've finally tracked down, but it never lost pressure or opened to the atmosphere. It would just leak down to about 25 PSI and stay there. And that's one of the reasons I think the compressor may need to be changed. Down that low it cycles on and off very rapidly and it may have been left that way for years.

If you have metal chips in the system, you need to completely flush it, or buy all new components. You might be able to clean all of the crud out of the parts, but the cost/risk analysis is not in your favor.

The OEM compressor was made by Delphi. At the time, they were owned by GM, but have since been spun off into an independent company that still supplies GM with OEM parts.

AC Delco was also once a GM company, but is just a brand name now. Their parts come from various sources (including Delphi). Sometimes they switch suppliers so it isn't possible to figure out who actually made the part in the AC Delco box, but there's a good chance that you would just be paying a premium to get the Delphi compressor anyway.

Four Seasons is, for the most part, a reputable aftermarket company, but the genuine OEM Delphi is only $20 more than the new 4S. Both probably source some of their parts from elsewhere I suppose, but as the OEM supplier, Delphi has to meet GMs quality control requirements.

Remanufactured units can be fine. Just not in AC compressors for some reason. I've read about more problems with remanned AC compressors than I can shake a stick at. For the $40 difference in price between the cheapest reman and the new Delphi, I'd go with the new Delphi. You'd spend more than that just swapping in a replacement reman if it failed. Think of it as cheap insurance!

The accumulator not only serves as a buffer for residual liquid, it contains the desiccant and tends to trap any debris that could make it through the orifice tube screen. If the system was properly vacuumed down when you changed the accumulator, and has not lost all pressure since, then you could probably get away without changing it again. That said, I think you will void the warranty on the new compressor if you don't change it.

Speaking of warranty, if anybody asks, you installed a GM Part # J44551-10 suction filter screen in the line to the compressor, because it is a warranty requirement that the system be flushed or a filter installed when the compressor is changed. (for more detailed info, please read http://buickforums.com/forums/threads/26737-Basic-principles-of-Auto-AC?p=132019#post132019). Warranty or no, you might install one just for your own peace of mind.

Having run the system low on refrigerant for years, the old compressor may be well-worn. The oil is distributed by the refrigerant, so running the AC in an undercharged condition means restricted lubrication for the compressor. The metallic flakes of compressor will plug up the inlet screen of the orifice tube, so I would strongly recommend replacing the orifice tube. They are dirt cheap anyway.

Forgot to add: Cranking the compressor over by hand is a very necessary step to prevent compressor damage by distributing the oil inside the compressor and ensuring that the compressor is not trying to compress straight oil. Oil is the lifeblood of the system. It is absolutely essential to ensure you have sufficient oil in the system. But it's not compressible! Your hand can't exert enough torque fast enough to damage the compressor, but an LT1 engine sure can.

Reading Fred's comment on flushing/replacing parts, I would like to reiterate that not all flushing is created equal. Those cans of flush sold in some parts stores can actually do more harm than good. Proper flushing requires high-volume equipment and special chemicals. The wrong chemicals can cause damage, insufficient flushing loosens up any debris, getting it ready to plug something up when you run the system.

Also, there is no way to flush the parallel-flow condenser in the B-body. If the condenser still works reasonably well, then the orifice tube filter screen will prevent any debris from travelling further into the system. If the condenser is plugged up, then it must be replaced. The orifice tube filter screen is actually a good canary of the condenser condition -- a few flakes of metal is nothing to worry about. A heavily encrusted filter screen is a strong sign that the condenser needs replacement.

If it is still working, and not making horrible noises... I wouldn't change it. I would simply open the line, change the orifice tube, refill.

He said the seal was leaking too.

Thanks guys, lots of good info here

So in absorbing this and thinking about it, and seeing as how I now have all the tools necessary to service the A/C system whenever I want, I may as well follow the path of least money spent. The seal set is only a few bucks, the accumulator is cheap, and the expansion tube is too. So I'll first replace the leaky seals at the back of the compressor and see what happens. I'm most curious to see if there are any more metal chips on the expansion tube.

A few followups- last time around I replaced the expansion tube with the "standard" one. This time I wanted to try the "automatic" one and see if the system behaves any differently.

The pressures I measure in the system seem ok according to the service manual, and the compressor itself doesn't seem to be exhibiting any signs of impending death.

Oddly enough the system holds a vacuum for as long as I can test, but under pressure it does slowly leak down to a point and stay there.

Ah, my bad. When you said the seal was leaking, I assumed you meant the shaft seal, not one of the o-ring seals at the back.

Actually, are you sure it is an o-ring seal and not the belly seal? These compressors are known for belly seal leaks.

Make sure you have sufficient oil in the system. Unfortunately there's no dipstick but these analyzers are a good guide:

http://www.aliexpress.com/item/Free-shipping-auto-ac-repair-tool-aircon-oil-checker-R134a-oil-analyzer/1744908399.html

You run the system for 5 minutes to get things evenly distributed then put one of these over the LP port and press it down briefly a couple of times, releasing a small puff of refrigerant vapour through the filter medium. If the filter is wet with oil from one end to the other, you are good to go. If the filter is dry, so is your compressor. Also, you can see how contaminated the oil is from any residue on the filter. It's not a precision measurement, but it's a darn sight better than guessing and a whole lot faster than disassembling the system to drain all the oil from each component into a measuring cup.

Ok, I got the testers on order. We'll see if we have sufficient oil in there.

I must confess as to not knowing what the belly seal is. I can tell you that I do see some oil on the bottom of the compressor, and it's fluorescent so it's the stuff I put in last year. Maybe a drop or two's worth, and I assume that it's coming out of the back where I get a solid hit on the leak detector.

I'd be inclined to change the evaporator and condenser along with the compressor if either the compressor ends up dying, or is leaking from somewhere bad, or if I just can't figure out where all the leaks are. Mainly because figuring out exactly how much oil is in there seems pretty hard.

The belly seals are the o-rings in the joints between the case sections. There are actually four separate housings forming the body, held together with six through bolts that pass from the
front nose plate and thread into the rear head plate. Most other horizontal compressor body sections are aligned with dowel pins, but not this style.

If the case is torqued -- either by improper installation or warping of the brackets over time -- the case can twist, causing a "belly" leak. That's why it is important to make sure the bracket lines up properly and then tighten the bolts to spec with a torque wrench, rather than just hammer the bolts in with an air gun or something.

To be fair, a belly leak can also occur on any compressor due to corrosion of the metal at the joint.

Under normal circumstances, there should be very little oil in the evaporator or condenser -- maybe an ounce in each. Most of the oil tends to accumulate in the accumulator or the compressor. If in doubt, more oil is better than less oil. The extra oil will reduce the overall efficiency of the system (from a cooling standpoint, oil is just taking up room that could be used by refrigerant), but too little oil will kill the compressor.

Do you have a recovery machine? If so, when the analyzer shows the oil concentration is low, you can add oil using something like this:
http://www.ebay.com/itm/331580840797

It has fittings to match the yellow lines. Suck out some refrigerant, pour however much oil you think is appropriate into the "can" (with the valve closed), pull a vacuum on the remaining space in the can, then with the valve down, open the valve and put the refrigerant back in the system, flushing the oil into the system with it.

There's also this style:

http://www.ebay.com/itm/180860638244

That connects directly to the LP port and lets you crank in oil by hand with the system under pressure. More money, but simpler in operation and it doesn't require a flow of refrigerant to use it.

And, with your location, stick with the stock orifice tube.

Ok, I did pick up one normal and one auto orifice valve. I see how the auto one works- it's clever but it does seem like one more thing that could break.

I will sniff around the compressor body and see if I get any hits. I hope the oil I see isn't leaking out of the compressor itself!

I don't have a recovery machine, just the usual round of DIY tools - manifold gauge set, vacuum pump, and leak detector.

I'm going to guess if people have been juicing the system up there may be an excess of oil in there, but as you mentioned without draining and measuring everything who knows how much is really in there.

lamune wrote:

Ok, I did pick up one normal and one auto orifice valve. I see how the auto one works- it's clever but it does seem like one more thing that could break.

I've heard good things and bad things about VOVs. At best they improve cooling at idle and low speeds and are most noticeable in hot climates. At worst, they make no difference and are a waste of money. I live in Northern Ontario so what feels like a heat wave to us is refreshingly cool to someone in Texas or Arkansas and I have to take the highway to go anywhere. So I never bothered trying one. Let us know how it works out for you.

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I will sniff around the compressor body and see if I get any hits. I hope the oil I see isn't leaking out of the compressor itself!

Get a compact fluorescent black light bulb from the local hardware store and put it in a drop light. The incandescent black light bulbs are useless. Get underneath and use the black light to see where the leak is. You may have to clean things off and run the system for a bit first since the oil will get pushed around by air flow over time. I have found that the leak detector is great for finding the general area, but visual confirmation is sometimes necessary to pinpoint a leak.

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I don't have a recovery machine, just the usual round of DIY tools - manifold gauge set, vacuum pump, and leak detector.

That's how I started. But I kept my eye on eBay etc. for good deals. Was outbid on things several times, but with patience I eventually got a great deal ($300) on a very clean Stinger. I added an inline filter to protect it, Chinese digital scale, extra yellow hoses, oil injector, valve core assortment, sealant detector, micron vacuum gauge, compressor inlet filter screen kit, etc. etc. I made my own recovery tank out of an old BBQ tank. It seems like a lot of money if you add it all up, but my immediate family has a small fleet of older vehicles that I look after so it has paid for itself many times over.

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I'm going to guess if people have been juicing the system up there may be an excess of oil in there, but as you mentioned without draining and measuring everything who knows how much is really in there.

Hence the need for the oil analyzers... You can usually find them at most DIY auto parts stores too, if you need them right away. Red Tek, etc. repackage them 2 for $5 or $10. So you don't have to wait for your order to arrive. But that bulk link is the best pricing I have found.

Buickwagon: Thanks for the tips

I'll try the VOV first and see how it works. If I don't like it switching it out is pretty simple.

One other thing popped up. The FSM says specifically not to use PAG oil to lubricate the seals when installing. PAG oil is what I used last year on the o-rings when I first fixed this thing.

The reason seems to be that PAG oil is hygroscopic and can turn acidic, and eat away at the fittings.

Asking the internet, the opinions range from "never use PAG oil!" to "I've used it for years and years and have no problems" to "I use motor oil" to "Any old grease will work"

I ordered a bottle of Delco 525 mineral oil just to be on the safe side (it's only $12) - any opinions here? Should I take everything off and re-lube with 525?

I always lube the o-rings with mineral based refrigerant oil. I'm not sure that it's any better than PAG, but I still have a quart bottle left over from the days of R12 systems. A little goes a long way!

The orange wagon would hold vacuum all day long,.

The core on the high pressure port would leak under pressure,.

i went to the JY and pulled a few,. then picked the nicest cleanest one,.

nice cold air now,.

Nick- funny you mention that, because a leaking high pressure port valve was the main problem I had when I got the car. I can understand why that would leak down to a point and stop.

Getting under there I see a nice glowing drip on the bottom of the compressor that's dripping onto the steering damper. No sign of drippage from the rear seal area. Looks like the compressor body itself is leaking.

I may just throw in some stop-leak and see what happens, and then during the off-season replace the whole system.

There are two kinds of "leak sealant". One helps seal O-rings by swelling them slightly. It's not so bad. The other claims to seal hard parts. It's very bad, reacts with any moisture and can plug up the system (particularly the orifice and parallel flow condenser) and any equipment used to service the system. I have a sealant detector kit and won't connect my equipment to a car that has sealant in it.

Depending on the severity of the leak, I think I would add oil and refrigerant for now, recover it when I had the new compressor in hand, then just replace the compressor, orifice tube, and accumulator (to protect the warranty) and install a suction screen (to protect the new compressor).

As for the high pressure port, it is a very poor design, well known to be susceptible to leakage. I bought a half-dozen brand new ones to have on hand and one of them even leaked. Make sure you have the plastic cap and that the o-ring is in place in the cap. That seems to be the most reliable way to prevent leakage from the port!

The oil analyzers came in, and I was able to determine that the oil in there is clean. Also that there's probably not very much of it. Seems logical that a belly leak would push the oil out of the system. That may also explain the metal bits.

I threw some R134 with leak sealer in there just to see what happens. At this point I'll probably just refill it when we're going on a trip. I'm not worried about the leak sealer- my plan is to just change out the compressor, evaporator, condenser, etc before the next two weeks of summer comes around again. If I'm going to go through the hassle of changing the compressor I want to be sure everything is clean. Also the condenser has a bunch of rock-strike damage anyway.

I did see that low-side refrigerant filter. How does that get installed? Just slice the hose and clamp it in place?

The one I am talking about (GM Part # J44551-10 suction filter screen) is a thimble-shaped screen that is pressed into the line feeding the inlet of the compressor. You unbolt the fitting at the back of the compressor and press it into the line. (I found it easiest to bring the lines up to the top of the engine and do it from above rather than from below). GM sells a special tool to install it, but the tool is awkward and with a little ingenuity and a c-clamp, not really necessary

There are also filters that can be cut into the line. AC Delco 15-10413 is cut into the metal tube on the liquid side of the condenser, replacing the orifice tube. Not really much protection for the compressor, IMHO. AC Delco 15-1747 is cut into the rubber line on the low pressure side, but I've never used it and I'm not dead certain it is the correct diameter for our lines. Looks like a recipe for leakage anyway, IMHO.

If you still have oil on the analyzer, I'd add 2 ounces and test again.

Thanks - I'll see how it looks after I shoot in a can of oil.

I will also chime in on flushing the system when you swap it all out..... don't and you'll be sorry. I bought one called flush in a bucket or something like that, worked great....all kinds of black crap came out of the lines...

I ran the A/C today, and it seems to be holding pressure- at least in the timespan of a week.

Ambient temperature was 82f, RH 45%. Low side pressure 33PSI, high side 185 PSI. The chart in the service manual seems to agree with those values, for what that's worth.

I was kind of hoping it would have leaked out so I could dump some more oil into the accumulator

The temperatures of the two pipes on the evaporator seem to be about the same temperature. There's a hole there that was blowing out cold air out of the firewall. Is that the drain? Is it supposed to be capped or covered?

Also the accumulator seems to be getting really cold. I don't remember if that's supposed to happen or not.

Temperature of the inlet and outlet of the evaporator should be equal, so that's a good sign. If the outlet was warmer than the inlet, that suggests an undercharged system. But the pipe should warm up considerably after the accumulator, otherwise it's overcharged. (speaking of refrigerant, of course. The oil charge cannot be determined this way).

The drain should have a rubber elbow so that wind doesn't just blow the condensate back into the car to rot out the floorboards. But at least it's not plugged up!

Ok, I should see if I can find the elbow for that!

Speaking of oil charge, I used the tester and it seems better. It's not clear from the instructions how long you should wait before reading it. If I look at it immediately it seems dry, but if I let it sit on its side for a few minutes, it looks wet.