Filling R134a from high side in liquid state with engine *OFF*

[WestPoint]

Greetings fellas and fellettes,

I'm in the process of wrapping up my AC (and cooling system) overhaul on a 2004 Honda CRV.

I came across several posts on the web where experienced guys fill a can of R134a upside down as a liquid into the high side while the engine is OFF. They say it is ideal as it gets the compressor working with refrigerant now in the system and thus is much faster than doing gas/vapor fill from the get-go. Also, there is no chance of slugging the compressor when filling liquid in the high side (can upside down) as it's on the other side of the AC system.

Has anyone done it this way? It sounds like if you gas fill R134a from the low side (suction) it can take a long while for the car to pull in the 18.7 oz (max) of refrigerant.

Any thoughts would be greatly appreciated. Keep it one hunid.

[JohnHere]

Has anyone done it this way? It sounds like if you gas fill R134a from the low side (suction) it can take a long while for the car to pull in the 18.7 oz (max) of refrigerant.

Yes, you can do it. But why? A long while? Not true. Why not avoid the potential risks of charging liquid into the system, pull a vacuum in the normal manner, and charge into the vacuum through the low side with gaseous refrigerant using an accurate refrigeration scale? It'll only take a few minutes, and the compressor won't engage anyway until you have sufficient refrigerant in the system.

[Cusser]

pull a vacuum in the normal manner, and charge into the vacuum through the low side with gaseous refrigerant using an accurate refrigeration scale? It'll only take a few minutes, and the compressor won't engage anyway until you have sufficient refrigerant in the system.

I'm NOT an AC professional, but I do this JohnHere's way.

[WestPoint]

Assuming the compressor is already filled with PAG, how is there wear on the compressor if the clutch doesn't engage and AC is not on?

[WestPoint]

I'm still confused as it seems the vast majority charge through the low-side as a vapor. But enough still charge as a liquid through high-side as refrigerant is in a liquid state on high-side anyway, plus engine is off. It almost seems like it's taboo that's why I'm trying to get clarification if it's ok.

https://www.autoacforum.com/viewtopic.php?p=476#p476

My plan is to vacuum down to 300-400 microns and ensure it stays below 1000 microns after 30 min. While the system is under a vacuum, add liquid refrigerant (can upside down) on high-side and see how much it will take. Afterwards, vapor fill the rest with engine running.

[Tim]

Simple answer.

If you hook up the gauge set and try to charge on the high side while the vehicle is running. You will blow your fingers off as you will be adding pressure into the can.

So if you want to get in the debate on charging. People go to extremes.

You can charge by a liquid on the low side. Just do it slowly as to not slug compressor with refrigerant. This is how it has been done for many many years.

You can charge on the high side if you have an R&R machine that works this way. It's done by the R&R machine while the vehicle is off.

[WestPoint]

Tim, thank you and I'm well aware that it's dangerous via the high side while the engine is on. I was merely asking why more people don't do it while engine is off.

[WestPoint]

Thanks for the info. So everyone compressor that gets filled as vapor via the low side suffers immediate wear and tear?

If that's the case, why aren't more filling through high side with engine OFF? All those Youtubers have been doing it wrong then!

[Tim]

Going far back as the early '80s. Charging a system via low-side liquid was the method used. There were not even 30lbs cylinders around and certainly no such thing as an R&R machine. When in a vacuum, you will pull pretty close to the entire first can into the system. Cycling the on/off switch when first starting the system moves the oil. Turning the compressor prior will also help lube the compressor once this is done. I love to see factual data that says the 5 seconds it takes to return oil to the compressor causes this damage!

I'm more worried about what people put in their systems or how cheap they try to repair a system. Then to always come back to vendors claiming crappy parts. It's one reason I may sound blunt at times. I have seen the crazy stuff that people try. Only to use a forum like this to bash a product. Never to mention they used BBQ gas and some magic sealer.

[WestPoint]

Thank you for your expertise guys. I am a noob but always willing to listen and learn. Tim, i wasn't aware of your site until after the fact but I already bought a Nissens branded scroll compressor. Does Sanden offer anything for the generation 2 (2002-2006)Honda CRVs?