’86 Volvo 244 AC

I posted this earlier concerning all the things to do with an A/C.. There have been black death problems associated with conversions though, but that is another subject..

I am going to do my cousins husbands A/C as soon as he gets money for the suction lines…. I found the leak and will photodocument it here and post it in the Repairs section… May be a week or so before this happens…

Anyway… Here is some info:

Do you know the condition of the system… When compressors go they often spread flakes of metal throughout the system. All of this metal has to be cleaned out with special cleaner using a special tool which uses compressed air to push it through the condenser and all the lines.

To do the Air conditioning properly you must follow the following steps.

Discharge the system in accordance with the laws of the land.

Remove the Compressor and inspect the lines for signs of destruction… The orifice tube is a very good indicator of the systems health although not all systems use an orifice tube.

If contaminated, the cleaner needs to be flushed through the system.. Oftentimes I remove lines if I have access to them and blow them out separately.

When I have any chance to replace an O ring, I do it. Ensure the O rings are coated with the proper system oil. I use a lot of PAG46…

The new compressor will need the proper amount of oil added to it if it is dry. Measure the proper type of oil you system takes… This information is very easy to find.. most take 5-12 ounces of oil. Put about 80% of the oil into the compressor directly and cycle it through by hand to ensure it gets in the compressor.

You can find your systems capacities of refrigerant and oil here—
http://www.techchoiceparts.com/refrigerant-and-oil-capacities

Replace the receiver dryer… This is good cheap insurance. Best place to buy inexpensive dryers is online… Some cost as little as $15 US.

Replace the schrader valves while it is open… cheap insurance here as well, many times leaks come from old schrader valves… Also, absolutely use a plastic cap on the system…

Assuming all the lines are now cleaned out reassemble the system. Add the remaining oil directly into the Receiver/Dryer.

Once the system is all re-assembled, then put it under vacuum. You can buy an inexpensive venturi system that works on compressed air that can pull vacuum but I don’t recommend it. HF sells a nice Vacuum pump for around $100 that does an excellent job on this.

Pull vacuum on the low side of the system system with your gauges until you have 30 inches of mercury. Do this for 5 minutes or so and then shut off the pump and turn off hose going to the low side. Wait about 15 minutes. Ensure your vacuum is still on 30 inches of mercury… If it lowers even one iota you have a leak and need to find it… Do not proceed until the system holds vacuum pressure like a rock… By the way, 30 inches of mercury is physically impossible on this earth but your gauge should read there.. the best you can do on Earth is around 29.something… Most gauges aren’t that accurate, the part that is important is that there is no vacuum leakage…

After you have confirmed that it holds vacuum, put the system under vacuum again for an hour… This will boil off all the moisture.. the physics lesson here is that moisture under vacuum lowers the boiling point to room temperature.. if you listen closely you actually may hear the moisture boiling away.

After this is complete, Then add the refrigerant… Your make and model will have an actual amount.. for example a Ford focus is 26 ounces. Oftentimes the cans are sold in 12 ounce cans so you know when you have 24.. You can get more specific by reading the weight of the can if you have a small scale…

Turn the engine on and turn the A/C on high..Set your idle where the manufacture recommends. Most cars this is around 1000-1400 rpms… At around 25 psi the clutch will kick in. This is when you will start to notice cooling… Add until the proper amount of refrigerant is added. For outside ambient air temperatures between 70-95 the reading should be 35 to 50 psi respectively. The high side should be somewhere around 2.2 to 2.5 X the ambient air temperature. So on a 70 degree day your low should read around 35 and the high should read 155 to 175. Different types of A/C units can be different, but these are ballpark figures. If you add the proper amount of refrigerant, your pressures should be there… There are also tables online to be more specific about pressures at ambient air temperatures.

Replace the caps and enjoy your new A/C…

If you have any other questions, feel free to shoot me a PM.

Here is my A/C box… I have been doing a lot in the last few days!

Cheers

Karl