AC Step-By-Step or Where to Start?

Gonzo1970

Gonzo1970

G-Body Guru
Supporting Member
Sep 30, 2018
576
93
No, he primarily works on much older cars that have aftermarket A/C units installed.

In his shop, my 86 GP is one of the newer cars. :D

-Gonz
 
Bonnewagon

Bonnewagon

Geezer
Sep 18, 2009
6,305
113
Queens, NY
YIKES! Fleabay wants almost twice what RockAuto does. For the price I think the brand new AC Delco 1520229 for $180 is what I would do.
 
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TURNA

TURNA

Geezer
Jul 24, 2009
8,729
113
Socialist NY
Your AC compressor should be the same as a Monte if you have the 305 in it Advance Auto Part # DW57231
 
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airboatgreg

airboatgreg

Royal Smart Person
Oct 2, 2016
1,670
113
It is easy to bolt on parts. The accumulator has to be changed with the correct amount of the right oil. Remember the accumulator holds the oil for the system.
Orifice needs to be changed. Sounds easy but a good way to ruin an evaporator as they can be tricky to remove.
System must be flushed.
Must be put on a vacuum pump that works.....
Just because the gauges say 30" does not mean it is doing its job. 5 or 6 hours is great. Never have seen a vacuum pump that is operated by air work.
I can opine more if you want as I have a lot of experience in this field.
 
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pontiacgp

pontiacgp

Canadian Prime Minister
Mar 31, 2006
25,638
113
Kitchener, Ontario
It is easy to bolt on parts. The accumulator has to be changed with the correct amount of the right oil. Remember the accumulator holds the oil for the system.
Orifice needs to be changed. Sounds easy but a good way to ruin an evaporator as they can be tricky to remove.
System must be flushed.
Must be put on a vacuum pump that works.....
Just because the gauges say 30" does not mean it is doing its job. 5 or 6 hours is great. Never have seen a vacuum pump that is operated by air work.
I can opine more if you want as I have a lot of experience in this field.
one question, is the accumulator the same as a dryer on the G body..?
 
Bonnewagon

Bonnewagon

Geezer
Sep 18, 2009
6,305
113
Queens, NY
Yes, the accumulator is also the dryer. It has desiccate inside to hold any moisture. Similar to the little bags you get with a new pair of shoes. I agree the accumulator and orifice should be changed if the system has been open to atmosphere and some kits include them. But is not always needed. My '05 Sunfire had a compressor fail but there was no leak- it just quit pumping. I disconnected the manifold, covered the ports with duct tape, and quickly swapped in a rebuilt compressor. I didn't change anything else because the system was never opened before this. I still vacuumed it down for an hour and then charged with the correct amount of R-134a. It works terrific and blows 35° below ambient.
 
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C

clemsparks

Not-quite-so-new-guy
Jul 26, 2009
24
3
Columbia MO
Must be put on a vacuum pump that works.....
Just because the gauges say 30" does not mean it is doing its job.
I'm curious what you mean by this. One argument would be that pulling 30 inHg vacuum defines that it is doing its job. What else do we need to be looking at in a vacuum pump?

To be clear...I'm not second-guessing you. I don't have a lot of experience in A/C work but am trying to learn as I go. Sounds like there's more to vacuum pumps than vacuum level in your experience.

Thanks!
 
Bonnewagon

Bonnewagon

Geezer
Sep 18, 2009
6,305
113
Queens, NY
A vacuum pump must be able to get to least 29" of vacuum. At that point water boils. Then the water vapor is drawn out via the pump. That removes any moisture in the system. The system only works at max performance with no moisture. The orifice is basically a tiny hole and as liquid freon exits the hole, it expands into a gas causing a temperature drop. Moisture can freeze up there and block the flow. Venturi pumps that run off a separate compressor are OK but a dedicated electric pump is much better but much more expensive.
 
Last edited:
69hurstolds

69hurstolds

Comic Book Super Hero
Jan 2, 2006
2,631
113
Watch your compressor inlet/outlet ports. Your original hose connection has a flat connector on it. The new R4 compressors have staggered heights because they were designed for 134 SYSTEMS. Not R12 systems. Meaning the physical connection points are height staggered. I guess so idiots could install them by not getting anything backwards. Who knows.

You'll hope to have the offset washers to fix that if you're retrofitting it on an 86. The compressor manufacturers won't tell you that anymore, but it's obvious R12 systems haven't been made in seemingly centuries. So good luck getting a new compressor with a flat connection point.
 

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