C900 A/C charge

charging

1.0kg for R12 if you know the proportional change for R134A to do the corrective maths. Sorry if that's no help. Cheers

For an easier swap over, consider R49/R314/RS24 rather than R134A. Compatible with old and modern synthetic oils, filled as a liquid rather than gas, and about 50-80% volume of the old R12. I used it in the Celica. It rocks.

The components of it also leak out at disproportionate rates, a lot of places won't touch a system that's been charged with a nonstandard refrigerant, and it's harder to find than 134. At any rate I did the conversion last weekend, charged it up with 24 oz of 134 and once again it blows cold. I still wish the filter/dryer had a sight glass but the air is cold, the high side pressure is reasonable, and it's not making any unusual noises so I'm happy. It's a nice system, uses a TXV instead of a silly fixed orifice so the charging is not nearly as critical, and the evaporator is easily accessible in case of bacterial or fungal growth.

975g on mine!

Look on the various "Do not touch a/c system idiot!" multilingual stickers on the fenders, you'll see.

Standard procedure is 80% R134a.

However, you do need to use a pressure gauge and some other stuff to do the retrofit. Also, there is a reason the R12 leaked out in place #1. So find out what has happened, a leaky hose, dried up seals etc. Fix it proper and do a correct R134a retrofit and the aircon will be nice and cold (not as cold as new but more than fine) and you will enjoy it for a good long time. However, if you go to Wal Mart and buy a $40 "AC retrofit kit" which has a can of "sealant" goo plus some R134a or a mix of propane/butane etc will only last a short time and not work very well at all. It's a half-assed solution.

Yes that's a given, there was a hose with a loose fitting between the rubber and metal so I replaced the assembly as well as all the seals. Also it's a

17 year old car and refrigerant does slowly leach through rubber hoses and seals so some loss of charge over time is normal.

I agree that the kits are a bit misleading, to do it right you really have to flush the system with solvent to remove all traces of the old oil, replace the expansion device and all the O-rings in the system and then use a decent vacuum pump to evacuate it for charging.

Is there a way to tell, ignoring the presence or absence of labels/stickers around the engine bay, what type of refridgerant is inside the A/C system? My 1985 900i doesn't have any stickers or labels saying it's been refilled with R134a but the compressor's spec plate says it's designed for R12. That could mean that the system still has R12 but then again it might not. Once I get the car running enough to renew it's rego and insurance after 2 years without any, I'll look at getting an A/C tech to explore the A/C system and figure out if it needs re-filling, etc.

Regards,

Craig.

Fair enough if you did a full conversion. Just that a lot of places will just drain and refill a "late" R12 system with R134, and add a "special oil" leak blocker to the synthetic oil.

I must see about getting aircon fitted to the Vert. Somedays are too hot, but still too wet for the roof down.

When they draw down the system, there is equipment that can tell you exactley what gas is in the system, before they either refill, or rebuild all the seals, replace the oil, and refill.

Well the system is an R12. All C900 had an R12 system. Generally speaking, if you didn't retrofit and there aren't any stickers or weird things (writing on compressor, non-stock hoses, etc) then it should never have been touched.

Mind you, my 1990 900turbo bears a sticker saying it contains "leak detection dye in A/C system", the brake reservoir has "134R" written in black marker, and the compressor has "don't use this port" on it also. My hoses are the original "Murray Manuli" date coded Feb 1990 or so. When I got the car, A/C belt missing, what does that tell you?

labels/stickers

You can evacuate some of the old refrigerant into a tank of some sort so that there's enough that some is in it's liquid state, then measure the pressure and generally get a good idea of what the substance is. If it's R-12 then it has value, if it's some other concoction you pretty much have to just throw it away.