ac compressor
05-08-2008, 08:41 PM
#16
hmmmmmm..... for a DIY ? First time out of the gate? NOT!
He could probably do the mechanicals, however the recovery, charge and test would be less painful if handled by the shop.
Yeah that's great only to find out the mechanicals didn't work after all and now you've got a $100 shop bill, still no A/C and back to square one.
and, if you follow the directions above:
A) your evaporator core will be oil soaked... way too much oil. And, don't mix PAG and Ester, determine what type is in the system first and stick with that.
Your own website says 4 - 6 oz's. I didn't say mix, in fact a Nippo 10P15E compressors recommended oil is PAG 46.
B) no hint about inspection for prior contamination, does not make sense to put a new or rebuilt unit in a vehicle with possible contamination
Good point
C) no notice of can right side up (vapor) or upside down (liquid)
Liquid charging can freeze the compressor. I also know how to heat the cans to increase pressure, but I didn't put that in here either.
D) replacing a drier does not insure moisture is gone
That is why you vacuum the system.
E) the depth of the vacuum, and altitude ....relative to the the ambient air temp determines when moisture's evaporation point starts, however neither guarantees total removal of moisture, its a matter of all plus time and purging
That's why you purge until there is no residual moisture
F) you don't need to jump the switch if you have allowed enough refrigerant into the system to overcome the low side cut out
I don't think there is a low side cut out on a 944
G) you can charge by liquid if you know what you are doing
Yes you can, but it is risky to do prior to getting the compressor turning.
H) you don't need to leave the windows open unless you are doing a major stress test or you want to listen to tunes
I) the pressures noted mean nothing unless they correspond to a Pressures and Temperatures chart for a specific refrigerant
R-134. It gets you in the ballpark, but you're right if you want to be **** about it get an A/C service book with diagnostics (like I have) and look up the aforementioned charts.
OMG
He could probably do the mechanicals, however the recovery, charge and test would be less painful if handled by the shop.
Yeah that's great only to find out the mechanicals didn't work after all and now you've got a $100 shop bill, still no A/C and back to square one.
and, if you follow the directions above:
A) your evaporator core will be oil soaked... way too much oil. And, don't mix PAG and Ester, determine what type is in the system first and stick with that.
Your own website says 4 - 6 oz's. I didn't say mix, in fact a Nippo 10P15E compressors recommended oil is PAG 46.
B) no hint about inspection for prior contamination, does not make sense to put a new or rebuilt unit in a vehicle with possible contamination
Good point
C) no notice of can right side up (vapor) or upside down (liquid)
Liquid charging can freeze the compressor. I also know how to heat the cans to increase pressure, but I didn't put that in here either.
D) replacing a drier does not insure moisture is gone
That is why you vacuum the system.
E) the depth of the vacuum, and altitude ....relative to the the ambient air temp determines when moisture's evaporation point starts, however neither guarantees total removal of moisture, its a matter of all plus time and purging
That's why you purge until there is no residual moisture
F) you don't need to jump the switch if you have allowed enough refrigerant into the system to overcome the low side cut out
I don't think there is a low side cut out on a 944
G) you can charge by liquid if you know what you are doing
Yes you can, but it is risky to do prior to getting the compressor turning.
H) you don't need to leave the windows open unless you are doing a major stress test or you want to listen to tunes
I) the pressures noted mean nothing unless they correspond to a Pressures and Temperatures chart for a specific refrigerant
R-134. It gets you in the ballpark, but you're right if you want to be **** about it get an A/C service book with diagnostics (like I have) and look up the aforementioned charts.
OMG
05-09-2008, 12:31 AM
#17
Yeah that's great only to find out the mechanicals didn't work after all and now you've got a $100 shop bill, still no A/C and back to square one.
This stuff ain't rocket science.
Ironic is it not? That is why one paragraph posted will not answer all the questions.
Your own website says 4 - 6 oz's.
You are correct. On a typical 944 compressor and drier R & R, we have found, over the past 15 years of doing this type of work, that is a reasonable amount of oil. What your post suggested is the following: "add 2 to 4 ounces appropriate PAG/Ester oil to compressor (bench prep)" + "Connect a can of 8oz Oil Charge (PAG/Esther oil) and charge oil into system." Hence you are suggesting by instruction to put 10 to 12 ounces in the system. So we say too much oil which soaks the evaporator coil and reduces heat transfer.
Liquid charging can freeze the compressor. Actually liquid or vapor can cool down a compressor. Charging by liquid through the high side is a normal procedure for those who know what they are doing. Review the compressor's high side circuit.
That's why you purge until there is no residual moisture And how many DIY's know when there is no residual moisture? Most DIY's don't have the equipment to purge nor equipment to check for moisture.
D) replacing a drier does not insure moisture is gone
That is why you vacuum the system. Quote "replacing drier will ensure all moisture in the unsealed system is gone." Taken verbatim by a DIY, means what is written. The purpose of a drier to is to a) store liquid refrigerant, b) acts as a filter, and c) (yes to a limit depending upon how much h20) remove residual moisture, however a drier does not ""ensure" all moisture in the unsealed system is gone".
I don't think there is a low side cut out on a 944
Read section 87 of the Porsche Shop Manual, or look at what is attached to the refrigerant hose between the condenser and the drier.
G) you can charge by liquid if you know what you are doing.
Yes you can, but it is risky to do prior to getting the compressor turning.
Nooooo. Getting the compressor turning has no affect, however "if you know what you are doing" you can charge by liquid all day long. But, given most DIY's don't have a Shop Manual, don't have all the tools or knowledge, for the cost (material, time, frustration) vs. benefit..... then recovery, evac, charge and test is best left to a professional (professional means a mechanic who works with you naturally... they are out there).
I) the pressures noted mean nothing unless they correspond to a Pressures and Temperatures chart for a specific refrigerant
R-134. It gets you in the ballpark, but you're right if you want to be **** about it get an A/C service book with diagnostics (like I have) and look up the aforementioned charts.
So you are suggesting that on a 50-60 degree ambient day during the early spring when a DIY has some free time, its OK if the high side is 200 psi? And then what is his "approx" "in the ballpark" going to be when he's sitting in traffic on the freeway when its 95-100F outside? And what is one of the common tell tale signs of air in a system? Knowing the relationship between pressures and temperatures is just one of the key cornerstones to understanding how the ac system works and how to trouble shoot it. Right?
One successful DIY fix will pay for all the required tools and books.
Maybe. And, maybe not. Read all the posts and you'll find more maybe nots.
I didn't say mix, in fact a Nippo 10P15E compressors recommended oil is PAG 46. You are correct, but "appropriate PAG/Ester" could be said better as "determine the correct oil to use, PAG or Ester......"
And you are correct on what many OE's recommend, such as PAG, however for most "conversions" Ester works perfect. Its amazing how many do an alternative refrigerant conversion or simple DIY work and can't seem to find the little sticker.
Cheers!
Confrontation is not a dirty word. Sometimes it's the best kind of journalism as long you don't confront people just for the sake of a confrontation.
Don Hewitt
This stuff ain't rocket science.
Ironic is it not? That is why one paragraph posted will not answer all the questions.
Your own website says 4 - 6 oz's.
You are correct. On a typical 944 compressor and drier R & R, we have found, over the past 15 years of doing this type of work, that is a reasonable amount of oil. What your post suggested is the following: "add 2 to 4 ounces appropriate PAG/Ester oil to compressor (bench prep)" + "Connect a can of 8oz Oil Charge (PAG/Esther oil) and charge oil into system." Hence you are suggesting by instruction to put 10 to 12 ounces in the system. So we say too much oil which soaks the evaporator coil and reduces heat transfer.
Liquid charging can freeze the compressor. Actually liquid or vapor can cool down a compressor. Charging by liquid through the high side is a normal procedure for those who know what they are doing. Review the compressor's high side circuit.
That's why you purge until there is no residual moisture And how many DIY's know when there is no residual moisture? Most DIY's don't have the equipment to purge nor equipment to check for moisture.
D) replacing a drier does not insure moisture is gone
That is why you vacuum the system. Quote "replacing drier will ensure all moisture in the unsealed system is gone." Taken verbatim by a DIY, means what is written. The purpose of a drier to is to a) store liquid refrigerant, b) acts as a filter, and c) (yes to a limit depending upon how much h20) remove residual moisture, however a drier does not ""ensure" all moisture in the unsealed system is gone".
I don't think there is a low side cut out on a 944
Read section 87 of the Porsche Shop Manual, or look at what is attached to the refrigerant hose between the condenser and the drier.
G) you can charge by liquid if you know what you are doing.
Yes you can, but it is risky to do prior to getting the compressor turning.
Nooooo. Getting the compressor turning has no affect, however "if you know what you are doing" you can charge by liquid all day long. But, given most DIY's don't have a Shop Manual, don't have all the tools or knowledge, for the cost (material, time, frustration) vs. benefit..... then recovery, evac, charge and test is best left to a professional (professional means a mechanic who works with you naturally... they are out there).
I) the pressures noted mean nothing unless they correspond to a Pressures and Temperatures chart for a specific refrigerant
R-134. It gets you in the ballpark, but you're right if you want to be **** about it get an A/C service book with diagnostics (like I have) and look up the aforementioned charts.
So you are suggesting that on a 50-60 degree ambient day during the early spring when a DIY has some free time, its OK if the high side is 200 psi? And then what is his "approx" "in the ballpark" going to be when he's sitting in traffic on the freeway when its 95-100F outside? And what is one of the common tell tale signs of air in a system? Knowing the relationship between pressures and temperatures is just one of the key cornerstones to understanding how the ac system works and how to trouble shoot it. Right?
One successful DIY fix will pay for all the required tools and books.
Maybe. And, maybe not. Read all the posts and you'll find more maybe nots.
I didn't say mix, in fact a Nippo 10P15E compressors recommended oil is PAG 46. You are correct, but "appropriate PAG/Ester" could be said better as "determine the correct oil to use, PAG or Ester......"
And you are correct on what many OE's recommend, such as PAG, however for most "conversions" Ester works perfect. Its amazing how many do an alternative refrigerant conversion or simple DIY work and can't seem to find the little sticker.
Cheers!
Confrontation is not a dirty word. Sometimes it's the best kind of journalism as long you don't confront people just for the sake of a confrontation.
Don Hewitt
05-09-2008, 12:54 PM
#18
Nordschleife Master
My advise FWIW, buy a compressor, $345 for a good remanufactured one with a one year warranty from HERE (no affiliation) + a new dryer + the oil they recommend.
Have an ac shop evacuate the system for you before you start and purchase an assortment of new seals from them.
Replace the compressor and seals yourself, don't forget the seals at the condensor and dryer, its an easy job. Add oil after the compressor is in place but before you fit the lines. Lube the new seals with the oil.
After everything is replaced and tightened down, do not attempt to start the compressor, drive it back to the ac shop to charge.
You will have saved yourself about $250 in labor.
Mike
Have an ac shop evacuate the system for you before you start and purchase an assortment of new seals from them.
Replace the compressor and seals yourself, don't forget the seals at the condensor and dryer, its an easy job. Add oil after the compressor is in place but before you fit the lines. Lube the new seals with the oil.
After everything is replaced and tightened down, do not attempt to start the compressor, drive it back to the ac shop to charge.
You will have saved yourself about $250 in labor.
Mike
05-09-2008, 01:56 PM
#19
Instructor
Join Date: Sep 2006
Location: Kansas City, MO
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I am not a professional wrench and have done all the a/c work on all my rides. I've never had to do the same car twice. A/C is very simple. Don't let some guy pushing his own stuff scare you off.
05-09-2008, 08:38 PM
#20
My advise FWIW, buy a compressor, $345 for a good remanufactured one with a one year warranty from HERE (no affiliation) + a new dryer + the oil they recommend.
Have an ac shop evacuate the system for you before you start and purchase an assortment of new seals from them.
Replace the compressor and seals yourself, don't forget the seals at the condensor and dryer, its an easy job. Add oil after the compressor is in place but before you fit the lines. Lube the new seals with the oil.
After everything is replaced and tightened down, do not attempt to start the compressor, drive it back to the ac shop to charge.
You will have saved yourself about $250 in labor.
Mike
Have an ac shop evacuate the system for you before you start and purchase an assortment of new seals from them.
Replace the compressor and seals yourself, don't forget the seals at the condensor and dryer, its an easy job. Add oil after the compressor is in place but before you fit the lines. Lube the new seals with the oil.
After everything is replaced and tightened down, do not attempt to start the compressor, drive it back to the ac shop to charge.
You will have saved yourself about $250 in labor.
Mike
