In the 88 Fiero service manual using R12, it says to charge the system with the can upside down. My understanding is the refrigerant will enter the system in a liquid state rather than a gaseous state if the can is upside down.

Does the same apply to R134? Should the system be filled with the can upside down?

You can fill it through the high side port by liquid. Engine off.

Takes about 10 seconds to empty a can vs 10 minutes by hooking into the low side port and charging with gas.

If you use the entire can there isn't much diference, which was you do it. It might fill a little quicker with the can upside down, but as far as the system goes, I'm not aware that it matters

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Ol' Paint, 88 Base coupe auto.
Turning white on top, like owner.
Leaks a little, like owner.
Doesn't smoke, unlike owner

If you turn the can upside down while filling through the low pressure port, engine/compressor on, the compressor can ingest a slug of liquid refrigerant. Which is about as destructive as driving your car into a lake. It's generally not recommended.

However, on the fiero the fill port may be on the other side of the car (I don't remember)... giving it plenty of time to boil and expand. In that case, it doesn't matter.

If you have a set of gauges, you can safely charge liquid into the low side. Just keep the low side gauge below 40 PSI while you charge. This will make the freon boil inside the charging line, it will be a gas by the time it enters the compressor.

This way is a lot faster than trying to charge with gas (IE the can right side up)

Max

The low side port can take the charge upside-down (as liquid) because it goes into the accumulator first. The accumulator stores the liquid until the system demand causes the liquid to change to vapor. Using the high side to charge is for specialty equipment only. Not a DIY kinda thing. This is only for an accumulator / fixed orifice tube system.

A receiver-dryer / expansion valve system is more complex and (depending on the location of the service port) usually requires filling the system with vapor with the can upright. The reason is that liquid cannot be compressed. If you feed liquid to the compressor you will bend the vanes inside. This is a Bad Thing.

GM cars use the accumulator / fixed orifice tube with the service port before the accumulator so upside down is no problem.

EDIT: Never blindly dump a can of anything into the system. Always use some kind of gauge. Over filling is as bad as under filling.

[This message has been edited by Hudini (edited 04-30-2007).]

quote Originally posted by Hudini: If you want a chemically superior product and are not scared of being different, try this. Works wonders on my old S10 Blazer with a 2.8L carb'd engine. http://www.autorefrigerants.us/ I am very pleased with the results. Been running it for 2.5 years.

This "chemically superior product" is nothing more than a mixture of propane and butane. They are great refrigerants and are used widely in industrial applications. The only thing wrong with these products is when they vaporize and mix with air they can form explosive mixtures. So if there is a small leak in the evaporator there is the potential to fill the cabin with an explosive mixture that is just waiting for a spark to go boom. Despite what the Envirosafe website says, the same is not true of Freon refrigerants. We all know that natural gas is widely used for home heating. Generally it is safe but every now and then a house goes boom due to a gas leak.

I've converted two Fiero systems to R-134a and if the system is healthy R-134a cools fine. So personally I don't see a necessity to charge the system with LPG.

[This message has been edited by sanderson (edited 04-30-2007).]

To each his own. That is why I posted "if you are not scared of being different".

By superior I mean the boiling point is colder than R-12. (-30 vs -21)

And the fact that a hydrocarbon based refrigerant is inside the cabin is why automakers do not use it. I use it because it cools far superior to R-134a in my S10 Blazer. No A/C on my Fiero, so can't use it there (I would if it were an A/C car).

IIRC those 'super' refrigerants only have a small percentage (2-4) of hydrocarbons in them anyway, that's how they get epa approved as there is minimal danger. However I don't think a/c shops like them since it would contaminate any existing refrigerant in their recovery machines.
Pure propane/butane though is another topic entirely (apart from being seriously illegal).