Modern A/C swap from donor?

[Supa.Slo.SS]

If you have everything there just replace the O rings, the drier and orifice tube and either charge the system with R134a yourself or pay someone. Dad and I have done this to half a dozen R12 systems (and he has done it since the 90's on off highway equipment) and if the compressor has been sealed it's almost always fine. I have killed 2 compressors doing this but the compressors were shot anyways and sat exposed to atmosphere for over a decade.

The amount of parts that will swap to an LS from the stock R4 system is small. The cost to get the existing system working is small if the compressor is fine.

You can get the stock system working for under $100. If it dies quickly you are out $100 but it's cheaper than dumping $700 into redoing the entire system or adapting a sanden compressor onto it and then making lines and brackets that will get used for maybe 1-2 years.

Do I replace the O rings with OEM one's? I remember reading that if switching to R134 you want to have different material/type o-rings, but not sure if you did that? If so, were do I buy them? Do you just charge it with straight Freon? No oil? What about evacuating the system of an remaining R12?

 

[81cutlass]

Do I replace the O rings with OEM one's? I remember reading that if switching to R134 you want to have different material/type o-rings, but not sure if you did that? If so, were do I buy them? Do you just charge it with straight Freon? No oil? What about evacuating the system of an remaining R12?

Yeah, the O rings should be replaced with the Green style. The old O rings are probably bad anyways. You can get a generic O ring kit from the auto parts store or order a specific seal kit for your make/model from online or any parts store.

You need to replace the drier, it's under $30. That has a lot of your oil in it. 4 seasons makes them and are direct fit. I also recommend pulling the evaporator and condenser to remove as much oil as you can. You can slosh some acetone in and blow the old stuff out with an air gun.

You need to add new oil that is synthetic PAG based.

If your system has existing R12 and want to be legal yes you need to evacuate any old stuff out. My bet is it's already fully leaked out. You need to fully evacuate the system before you can put R134 in it anyways.

 

[Supa.Slo.SS]

Yeah, the O rings should be replaced with the Green style. The old O rings are probably bad anyways. You can get a generic O ring kit from the auto parts store or order a specific seal kit for your make/model from online or any parts store.

You need to replace the drier, it's under $30. That has a lot of your oil in it. 4 seasons makes them and are direct fit. I also recommend pulling the evaporator and condenser to remove as much oil as you can. You can slosh some acetone in and blow the old stuff out with an air gun.

You need to add new oil that is synthetic PAG based.

If your system has existing R12 and want to be legal yes you need to evacuate any old stuff out. My bet is it's already fully leaked out. You need to fully evacuate the system before you can put R134 in it anyways.

Thanks for info! I actually already have green o-ring set ready to install that I bought so I could get free shipping from Summit some time ago. Sorry for continuing with questions, but how much of the PAG oil do I need to add to the system? Is there a cheap DIY way to evacuate the system? Or would I need a professional to do it? Also, once it's all ready to be charged, what about the actual fittings to actually charge it? I have also read, that those are garbage and leak. Is there is a good brand you typically use?

 

[Supa.Slo.SS]

Yeah, the O rings should be replaced with the Green style. The old O rings are probably bad anyways. You can get a generic O ring kit from the auto parts store or order a specific seal kit for your make/model from online or any parts store.

You need to replace the drier, it's under $30. That has a lot of your oil in it. 4 seasons makes them and are direct fit. I also recommend pulling the evaporator and condenser to remove as much oil as you can. You can slosh some acetone in and blow the old stuff out with an air gun.

You need to add new oil that is synthetic PAG based.

If your system has existing R12 and want to be legal yes you need to evacuate any old stuff out. My bet is it's already fully leaked out. You need to fully evacuate the system before you can put R134 in it anyways.

Also, I did a quick check on AutoZone and they have different orifice tubes, some are a few bucks others are $25 & one is $43, does it matter which one?

 

[bs009]

you can't use the ls style compressors. G-body units kick the compressor into on & off cycles, where the new compressors have variable internals. These compressors will work for a while with g-body controls, but WILL eventually fail. Wish I had known that earlier with my LS swap done back in 2002'.

FWIW in case someone else is looking at swapping over to a newer compressor as part of an engine swap:

Newer AC compressors use variable displacement compressors so they can modulate how much volume they're pushing and don't need to cycle because of it.
G-body's use one low side switch to control the AC but newer engines also have a high side sensor to see how much pressure the compressor has built up. The only thing the HVAC controls in the car do for AC is to kick on the AC compressor since they are wired to the low pressure switch and then to the compressor. In a swap you would just rewire this to instead go to the AC request pin on the PCM and it would decide if it can turn it on or not based on what the engine is doing and what the pressure in the line is.

You can make it run like it would have from the factory by adding the high side pressure sensor, I'm doing that in my GP but with a V5 compressor and this fitting on the high side on the condensor:

# 6 Inline Hose Adapter with 10mm Switch Port

This is a #6 (3/8") Female Oring to #6 (3/8") Male Insert Oring Inline adapter with 10mm switch port. The 10mm switch port is ideal for metric switches or transducers.

coldhose.com

I had a really hard time finding an adapter/fitting like that but I'm glad I did.

I am also still running the low side switch too though so it won't kick on unless the PCM tells it to and the low side switch is closed too. Been running great so far for the last 2 years

 

[81cutlass]

Thanks for info! I actually already have green o-ring set ready to install that I bought so I could get free shipping from Summit some time ago. Sorry for continuing with questions, but how much of the PAG oil do I need to add to the system? Is there a cheap DIY way to evacuate the system? Or would I need a professional to do it? Also, once it's all ready to be charged, what about the actual fittings to actually charge it? I have also read, that those are garbage and leak. Is there is a good brand you typically use?

An electric or siphon vac pump can be a good investment. If you don't own one you'll need a shop to do it. I use Dad's siphon pump that connects to the air compressor that he's had for 30 years. Vacuuming the system also removes any left behind moisture.

The adapter r12 to r134 fittings are kinda junk. I just remove them when I'm done. That way they won't leak. I'm sure ac decent one exists but I don't bother. Youd need a set of gauges also.

Oriphice tubes, I go with the cheap 97 cent ones of rock auto. The expensive ones are self adjusting and I'm not sure what they do.

 

[airboatgreg]

yes I do. Everything is there and functional just doesn't blow cold air.

Then I would convert to R134A like i did. Blows cold. Just has to be right

 

[565bbchevy]

I bought this a few years ago and for a few dollars less but worked really well when it was time to charge the new AC set up in my Regal.

2.5 CFM Vacuum Pump

Amazing deals on this 2.5Cfm Vacuum Pump at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

 

[Supa.Slo.SS]

Then I would convert to R134A like i did. Blows cold. Just has to be right

Did you take the same approach as 81Cutlass? Vacuum out old system, green O-rings, accumulator, orifice tube, pag oil and refill with 134?

 

[airboatgreg]

Did you take the same approach as 81Cutlass? Vacuum out old system, green O-rings, accumulator, orifice tube, pag oil and refill with 134?

Yes. Very important to flush system an use a good vacuum pump. Not all vacuum ums are created equal