AC compressor question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**7D2N** · 09-20-2012, 07:00 PM

I was cleaning up a used 72 big block AC compressor for my blazer and I tipped the compressor and some oil fluid leaked out, can someone tell me if I need put more in and if so what of fluid type it is?

Thanks 7D2N

rsavage · 09-21-2012, 07:53 AM

The Four Seasons AC system requires 10 oz. of A/C oil. It is old oil that ran out. Not all of the oil stays in the sump of your compressor - some in the dryer, evaporator etc. I am not an AC expert at all. That being said, if the parts you have were from a system that wasn't converted from R12 to another refrigerant, the oil is mineral oil. You can take the drain plug out and drain the rest of what is in it out. Other oils are used with different refrigerants. Your parts (lines evaporator, condenser)will need to be flushed ( you can buy a can of A/C flush (do not flush the compressor or dryer/filter as you will replace the dryer filter) and about 5 oz of oil added to the compressor through the drain plug IF it is dry before installation and the rest pulled in via vacuum when the charging process begins. Replace your filter/dryer. Your system is "open" so there will be moisture in it which is death to AC. My advice would be to put it together and take it to someone who knows what they are doing to pull a vacuum and both add the rest of the oil and recharge. You can still find R12 on Craig's list. You will need 3lbs. 4 oz. of refrigerant.

61_FL_Apache · 09-21-2012, 07:11 PM

I 2nd the tip on using an expert!

I would convert to 134a. R12 is hard to find these days.

**7D2N** · 09-21-2012, 09:56 PM

Thanks Guys. I have been collecting AC parts to fit the big block in my Blazer, is it a big deal to convert to 134a.? should I have not wasted time and $ and went with after market?

Thanks
7D2N

rsavage · 09-22-2012, 12:51 PM

It is not hard to convert to 134a. However R12 cools much better and it is easier and cheaper to get now than it was a few years ago. Check out Craig's list. I found two sources at $10-15 per can last spring when I did the Blazer AC. I coverted the 70 shortbed to 134a a couple of years ago and wish I had kept it R12.

**7D2N** · 09-24-2012, 07:01 PM

rsavage, I'll get the system installed go with the R12 for now.

Thank you.
7D2N

09-20-2012, 07:00 PM	#1
7D2N Senior Member Join Date: Aug 2007 Location: Morgan County Utah Posts: 718	AC compressor question I was cleaning up a used 72 big block AC compressor for my blazer and I tipped the compressor and some oil fluid leaked out, can someone tell me if I need put more in and if so what of fluid type it is? Thanks 7D2N Attached Images

09-21-2012, 07:53 AM	#2
rsavage Registered User Join Date: Aug 2009 Location: Alden NY Posts: 2,705	Re: AC compressor question The Four Seasons AC system requires 10 oz. of A/C oil. It is old oil that ran out. Not all of the oil stays in the sump of your compressor - some in the dryer, evaporator etc. I am not an AC expert at all. That being said, if the parts you have were from a system that wasn't converted from R12 to another refrigerant, the oil is mineral oil. You can take the drain plug out and drain the rest of what is in it out. Other oils are used with different refrigerants. Your parts (lines evaporator, condenser)will need to be flushed ( you can buy a can of A/C flush (do not flush the compressor or dryer/filter as you will replace the dryer filter) and about 5 oz of oil added to the compressor through the drain plug IF it is dry before installation and the rest pulled in via vacuum when the charging process begins. Replace your filter/dryer. Your system is "open" so there will be moisture in it which is death to AC. My advice would be to put it together and take it to someone who knows what they are doing to pull a vacuum and both add the rest of the oil and recharge. You can still find R12 on Craig's list. You will need 3lbs. 4 oz. of refrigerant. __________________ 1961 C1 Corvette 1959 El Camino 350 TPI, 9" 4 w disc 69 Blazer K5 - sold July '20 2021 Durango RT 5.7

09-21-2012, 07:11 PM	#3
61_FL_Apache Who Me? Join Date: Sep 2010 Location: Royal Palm Beach, FL Posts: 4,067	Re: AC compressor question I 2nd the tip on using an expert! I would convert to 134a. R12 is hard to find these days. __________________ Steve 1997 Tahoe LT 4D 2WD (DD) 2001 Blazer 4D 2WD 1961 Apache 10 (sold) 1965 C10 Stepper (sold)

09-21-2012, 09:56 PM	#4
7D2N Senior Member Join Date: Aug 2007 Location: Morgan County Utah Posts: 718	Re: AC compressor question Thanks Guys. I have been collecting AC parts to fit the big block in my Blazer, is it a big deal to convert to 134a.? should I have not wasted time and $ and went with after market? Thanks 7D2N Attached Images

09-22-2012, 12:51 PM	#5
rsavage Registered User Join Date: Aug 2009 Location: Alden NY Posts: 2,705	Re: AC compressor question It is not hard to convert to 134a. However R12 cools much better and it is easier and cheaper to get now than it was a few years ago. Check out Craig's list. I found two sources at $10-15 per can last spring when I did the Blazer AC. I coverted the 70 shortbed to 134a a couple of years ago and wish I had kept it R12. __________________ 1961 C1 Corvette 1959 El Camino 350 TPI, 9" 4 w disc 69 Blazer K5 - sold July '20 2021 Durango RT 5.7

09-24-2012, 07:01 PM	#6
7D2N Senior Member Join Date: Aug 2007 Location: Morgan County Utah Posts: 718	Re: AC compressor question rsavage, I'll get the system installed go with the R12 for now. Thank you. 7D2N



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