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AC Compressor's


Scotty

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In the old days I never noticed AC Compressors having to be replaced, as a matter of fact I don't think I ever replaced one. Is it my imagination or has the frequency of replacing compressor's increased from what it once was? Many of the failures eminate from the hub bearing, how can that bearing be improved to stop the failing that is taking place or has it been improved in later years? Personally I think this type of field information regarding component failures should be considered by engineers designing tomorrows components. This is an observation and not a criticism, lets face the fact that the Cadillac's of old NEVER needed compressor replacement and the AC systems were bullet proof, that is the direction to head. Obviously the compressors of today are smaller, lighter, use R134, have to deal with serpentine belt stresses and need to deal with engines that put out a lot more heat. Is the increased frequency of failure part of a "learning period" where the frequency of failure will improve over time or is this failure rate considered normal now? Mike

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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I think it is a problem with the sub-contractor used by GM. Your compressor is made by Delphi. They manufacture the same components for several other makes including Honda and BMW among others. I often find that Delphi parts break more often than other makes of parts. For example, the Delphi alternators on Honda's are for lack of a better word, crap. The compressors on Cadillac's as you know also have problems. Most Delphi products seem to last for about 4 years under normal use. Alps is another part company I have a low opinion of. I like parts made by denso, standard, deka, timiken, and TRW. They seem to make decent stuff.

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I think it is a problem with the sub-contractor used by GM. Your compressor is made by Delphi. They manufacture the same components for several other makes including Honda and BMW among others. I often find that Delphi parts break more often than other makes of parts. For example, the Delphi alternators on Honda's are for lack of a better word, crap. The compressors on Cadillac's as you know also have problems. Most Delphi products seem to last for about 4 years under normal use. Alps is another part company I have a low opinion of. I like parts made by denso, standard, deka, timiken, and TRW. They seem to make decent stuff.

You mean my compressor is not made by AC DELCO? Mike

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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Perhaps it's not that compressors are of less quality; maybe it's the fact that cars are lasting longer. Depending on how far back we go, I remember 100,000 miles was considered high mileage. I think this is proven by the fact that the maximum reading on odometers into the 80s and early 90s was only 99,000 miles. Today, it’s standard for odometers to allow readings up to 999,000 miles. So maybe it’s more about perception because cars are lasting longer, which equates to compressors wearing out, etc. Any thoughts?

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Perhaps it's not that compressors are of less quality; maybe it's the fact that cars are lasting longer. Depending on how far back we go, I remember 100,000 miles was considered high mileage. I think this is proven by the fact that the maximum reading on odometers into the 80s and early 90s was only 99,000 miles. Today, it’s standard for odometers to allow readings up to 999,000 miles. So maybe it’s more about perception because cars are lasting longer, which equates to compressors wearing out, etc. Any thoughts?

Thats a possibility but during the 100,000 miles that cars used to last, you never changed the compressor.... Personally I think that there is a lot of stress on the hub bearing and its not up to the task. My Deville has about 55,000 miles on it. Mike

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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Most FWD Northstar Cadillacs use the Dephi H6 compressor, If you take the compressor out, there is a sticker on the side of it.

http://www.delphi.com/products/auto/comfort/climate/

http://delphi.com/pdf/h/cc_h6comp.pdf

Thanks, then if its Delphi maybe they are not up to the task over the long haul. I just thought that Delphi and Four Seasons were aftermarket units and that the OEM unit was AC DELCO.... that is ONE reason I bought my new compressor from GM... Mike

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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i have noticed todays compressors are aluminum,and isnt r-134 a higher pressure system.or is it that all new technologies heve to be revised (debugged)or whatever.by the time they get something right it changes again.

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My last car '92 Deville was 8 years old with 125K on it when I traded it. Never a problem and only topped off the R12 about a year before I traded. Maybe it's like Guru say's, you only hear about the problems here, not the millions that are running around trouble free, though I would admit 55K sure seems premature. 86K on mine and so far trouble free (knock on wood). I do recall changing a bearing on my '72 Deville.

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good question! just yesterday I was thinking of the same thing I have a 77 riviera with a 403 and a A6 compressor with 166000 mi. a couple of years ago the clutch came apart and this month I replaced it. (Had to buy a sae hub installing tool the 97 is metric), It has the original pully hub assembly, the whole unit runs very quiet. For over 2 years the compressor did not turn I thought I would have trouble with it but it runs great. You would think the pulley bearing would have had to be replaced during 166000 mi. It needs r12 but still runs very quite the 97 gets noisier when low on r134 I think the 97 is a d6 Im just guessing but isnt that the same design axial 6cyl? I think quality has something to do with this problem with these space age metals and grease they should be able to overcome other obstacles. Just a thought Mike

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On the older cars , back in the 70's and so...the AC compressors on GM cars were huge units that could refrigerate a reefer in all likelyhood. In fact, they could cool a school bus. As such, they were very understressed, used a separate oil bath for the bearings and swash plate, and didn't have the serpentinve belt loads. Even when those units were converted to the cycling compressor style units in the late 70's they held up extremely well due to the low stresses.

I also think that there is something to the fact that the cars back then did not last nearly as long and, with a multiple belt V drive, people would just not fix the AC if it caused a problem. They would take the belt off and drive the car without AC. AC was an option back then that was not that high in penetration so AC was a bit of a luxury that many second and third owners (at the high end of the mileage scale) did not consider something to fix.

Todays compressors are much smaller and far far more efficient in terms of the energy they take to drive them and the fuel economy penalty they impose. They are more highly stressed so anything that is not right in the system will tend to show up at the compressor. The compressors run with oil in the refrigerant that is not as good a lubrication system as having a separate oil bath...but it works fine as long as everything is OK. Newer engines rev much higher and spin the AC compressor to more RPM as a result... Remember an engine from the 60's and 70's that regularily shifted at 6500 RPM....??? Also, with the serpentine belt, fixing the compressor is no longer and option. If the compressor hub bearing fails then the entire belt drive is out of commission so it has to be fixed instead of simply cutting that belt off. Plus, there are far more AC compressors on the road today. It is extremely rare to see a car without AC...I don't even know what cars could be ordered that way anymore. So, with the penetration of AC nearly 100% on cars there are bound to be "more" failures. Probably not more failures in terms of percentage of the units out there failing...but more failures in terms of absolute numbers to read about. R134a cnversions done poorly on many of the cars inquestion here also contribute to some failures, I'm sure.

I would say that the durability goals and life cycle design of the compressors has increased dramatically over the older systems. They are operting at higher speeds,, higher loads, in higher underhood temps, etc....so if anything goes wrong it is maybe more likely to take out the compressor...but I don't think that they are failing more than they used to...

Thank bbobynski, you are correct I HAVE cut my share of AC v-belts over the years... In addition, I have seen my share of cherry red hubs and squeeling belts in the old days.... I had forgotten! I don't think we were apt to get the AC fixed in those days wereas today its become a norm and necessity. My wife refuses to ride in my car with NO AC... Thanks for the insight, Mike

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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Another thing to consider is the number of compressors replaced when only the shaft seal or the clutch bearing is bad.

Most shops won't even replace a shaft seal anymore.....

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Who says the old compressors didn't used to go out? I don't know how many A-6 compressors I replaced on my 75 Cadillac not to mention expansion valves and POA valves. Maybe it was because they were rebuilt compressors but it seems like I replaced one a year. Also, the clutch didn't cycle on and off but it stayed on constantly as long as the selector was in any position other than "OFF" or "ECON." The valves regulated the freon flow. I did tend to always leave the selector in the "AUTO" position so the compressor ran year round.

Max

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I have often wondered if it where better to leave them run rather than go from 0-10,000 rpm in an instant, countless times.

That's histerical! I never thought about that. The cycling must cause a good amount of internal stresses... Maybe this is a dumb question but why do they cycle? I am sure it's related to fuel efficiency. What occurs for the cycle off and cycle on to happen, temp or pressure thresholds? Is any consideration given to throttle position, will the compressor be cycled off with hard acceleration? Time to buy a manual... Mike

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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WOT will disengage the compressor. Assumption is that you want max power. I'm not sure if cycleing is related to fuel efficiency or not but as I recall it aims to keep the tempurature at 35 degrees at some point in the line. Can't recall where. So it cycles off when reached and back on when it climbes to some predetermined temp, I forget what it is, probably about 40. The more I think of it, I think it may be for fuel efficiency. I am far far from an A/C expert so this may not be exact.

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