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Need steps to replacing Air compressor


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daytooday's Avatar
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July 14th, 2011, 9:04 PM   #1  
Need steps to replacing Air compressor

2001 Suburban, I need the steps to replacing the compressor,drier and tube. I have helped with this before but just wanted to make sure it didn't need to be done in a specific order.

thanks

 
spinne1's Avatar
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July 15th, 2011, 12:33 AM   #2  
1) hook up gauge set to high and low ports
2) recover r134a with recovery machine
3) remove compressor, drier, and tube
4) inspect tube for debris. If all is clean, put new parts in place and coat new green o-rings with either Nylog or mineral oil. If it is dirty, consider taking the whole system apart and flushing the condenser and tubing.
5) Determine how much oil has been removed by draining each part removed and measure it
6) Add the same amount of oil back as has been removed into the accumulator and compressor and piping (I believe you need PAG 150, but check for sure.)(Also, follow the compressor manufacturer's instructions on determining how much and then putting the oil in it.)
7) Put system back together if haven't already.
8) Vacuum pump for at least 20 minutes, but preferably several hours.
9) See if your gauges show that the system is holding the vacuum. If so, charge the system to the specified weight (4.0 lbs on a 1995--your mileage may vary.) If not, you have a leak. Find the leak and fix it. Then revacuum and charge.

 
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July 15th, 2011, 9:55 AM   #3  
Its my understanding that once the dryer has been open and installed you need to act quickly (hours not days) to get the system evacuated and charged or the dryer will start to do what its supposed to do and adsorb moisture from the environment...

 
daytooday's Avatar
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July 15th, 2011, 12:43 PM   #4  
How do you vacuum pump the system

 
73shark's Avatar
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July 15th, 2011, 1:25 PM   #5  
You connect a vacuum pump to the gauge set. After pulling a hard vacuum for several hours (this will remove most of the moisture in the system), close the gauges & shut the pump off to ensure the vacuum holds and there are no leaks. Then you can fill the system.

As in2pro stated, you'll need to get the system closed quickly after opening and installing the new drier.

If you can stand releasing a very small amount of R134a, you can recover most of it by attaching an empty refrigerant bottle that's sitting in ice water. At today's prices for R134a, it's worth buying an empty if you don't have one.

 
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July 15th, 2011, 1:31 PM   #6  
Harbor freight has some fairly inexpensive equipment for pulling the vacuum as well as gauge sets, it will still cost you money but probably cheaper then having it done and you will have the knowledge and satisfaction of doing it yourself...

 
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July 15th, 2011, 1:41 PM   #7  
The project is probably a medium skill level repair not because of difficulty but because of the steps and procedures involved in doing it right. You don't necessarily need to get it perfect, but the better the job the longer the repair should last.
I have heard of folks replacing most of the major components and charging the system without evacuating and it will most likely work but will not cool to its best or last as long.

 
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July 15th, 2011, 2:31 PM   #8  
Posted By: in2pro I have heard of folks replacing most of the major components and charging the system without evacuating and it will most likely work but will not cool to its best or last as long.
That sounds like the old "purge and release" method when freon was about a $1/lb. You'd fill the evacuated system and then release the freon and then evacuate and refill. Would be prohibitively expensive.

daytooday: Don't forget to replace the refrigerant oil that's in the components you are replacing.

 
daytooday's Avatar
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July 15th, 2011, 4:38 PM   #9  
Oil already in?

it says on the new compressor that it has been filled with 6.8 oz of PAG oil. Is this enough oil. I have replaced compressors before without pulling a vacuum. And they seemed to have done ok.Do you have any idea on how much a vacuum gauge would cost at Harbor Freight and what kind to buy. Is there a flush that i can buy to flush the system before I remove teh old or any any point tomake sure I don't get any of the particles let in the system

 
spinne1's Avatar
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July 15th, 2011, 5:43 PM   #10  
Enough oil? Hard to say. It depends how much is left in the components left in the system. It depends if you had a catastrophic loss of r134a. If so, some oil went out with it. You also need to drain your old accumulator and add back that amount of oil.

You do NOT want to fill your system without vacuuming first. You need to remove the moisture and that is how you do it. Also, the vacuum helps draw the r134a in when charging.

Vacuum pumps are often a "free tool rental" tool at some auto parts stores. Call them up and ask until you find one. If you get one from Harbor Freight it will be minimum of $99:

Electric Vacuum Pump - 2.5 CFM
Air Conditioning Vacuum Pump - Two Stage, 3 CFM

I got mine from Craigslist or ebay (can't remember) and it is a 5 CFM pump from Mastercool. You CANNOT use those super cheap vacuum pump devices from Harbor Freight that hook up to an air compressor. They are useless.

As for flush, I would not do it unless I knew what I was doing. It is expensive to buy flush equipment and also too much can be done wrong and you could make your system cool worse.

 
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