Automotive Air Conditioning Information Forum

I'm going to be helping a friend charge the AC in this car. The tag on the radiator support says a min of 0.77 lbs to a maximum of 0.90 lbs. Every online source chart that I have found says 17 ounces.
I'm not sure to go with the tag on the car or if the online references show more because maybe it was discovered at a later date that a max of 14.4 ounces was not enough.

What source would you go with? Thanks.

The under-hood decal always takes precedence over all other specs. If given a range like the decal indicates, I would charge it to the maximum amount by weighing the refrigerant into a well-held vacuum, then checking the pressures and center vent temperatures. If performance is satisfactory, I would leave it at that.

This car is about 18 years old and has a direct-drive, electronically controlled, variable-displacement compressor. Did the car experience a catastrophic A/C failure of some sort, or did the refrigerant leak out slowly over time to where the system wouldn't cool anymore?

JohnHere wrote: ↑Mon Aug 19, 2024 9:19 pm The under-hood decal always takes precedence over all other specs. If given a range like the decal indicates, I would charge it to the maximum amount by weighing the refrigerant into a well-held vacuum, then checking the pressures and center vent temperatures. If performance is satisfactory, I would leave it at that.

This car is about 18 years old and has a direct-drive, electronically controlled, variable-displacement compressor. Did the car experience a catastrophic A/C failure of some sort, or did the refrigerant leak out slowly over time to where the system wouldn't cool anymore?

They bought the car a few years ago with non-working air. It still has about 30 psi on both sides in the system so I think it probably leaked out over time. I looked everything over that I can see and used a UV light over everything to see if maybe there was some dye put in the system at some point but I didn't see any signs of any. I didn't see any signs of oil seepage either. He is going to have the rest of the charge evacuated before bringing the car back over.

We don't know the car's service history and don't know whether the A/C system has ever been recharged. That said, the source of the leak might be the compressor shaft seal. Since the system hasn't been run for at least a few years, it could be a lack of oil at the seal causing the (only??) leak. The system still has some static pressure, which is a good sign.

After having the remaining refrigerant recovered, taking note of the amount of oil (if any) that the machine collects, and you get the car back, replace the desiccant kit in the Receiver/Dryer while you're at it. I believe the R/D is integral with the condenser on this car. After ~18 years, I recommend not taking a chance on the integrity of the old desiccant bag. If it ruptures shortly after you service the system, desiccant beads will spread downstream, requiring additional time, money, and frustration to fix.

Then, add back into the system whatever oil the recovery machine collects, evacuate the system for at least one hour, and determine whether it holds a vacuum. If so, recharge it by weight according to the specs on the under-hood decal, and performance test. Hopefully, that'll be be all that it needs.

Thanks for the information. We shall see how it turns out.

I charged the car to the 0.90 lbs spec on the sticker but found that the compressor will not kick on. It has a two wire connector and I had power on one pin and ground on the other so I guess the electrical part of the compressor is not good. I tried tapping on the end of the compressor and that did nothing.

According to the information I have, that car's compressor is directly driven by the engine and doesn't have a clutch, meaning that the compressor runs whenever the engine is running. Instead of a clutch cycling system, this system uses an ECM-governed electronic control valve to vary the compressor's displacement depending on the heat load.

JohnHere wrote: ↑Tue Aug 20, 2024 4:56 pm According to the information I have, that car's compressor is directly driven by the engine and doesn't have a clutch, meaning that the compressor runs whenever the engine is running. Instead of a clutch cycling system, this system uses an ECM-governed electronic control valve to vary the compressor's displacement depending on the heat load.

Interesting. The compressor was not coming on and the gauges stayed at a static pressure which was close to 90 psi on both gauges. The power wire at the compressor connector only had power on it when the car was running. Key on, engine off there was no power at the connector. There was a ground on the other wire in both situations. Because of this, it appears that there is a request to the compressor when the car is running and the compressor should be working. I'm not sure what else to diagnose to determine why the compressor is not doing anything.

I do want to add that when the AC button is pressed and the blower fan is turned on, the radiator fan does come on, so it seems like the system is getting the inputs it needs to work. Low pressure line is not getting cold at all so the compressor is not doing anything. I had my fiancé turn the system on while I looked at the compressor and noticed nothing different other than the radiator fan coming on.

I think you're right that the system is getting the proper electrical signals to run. Additionally, if the pulley on the front of the compressor is turning with the engine running, then the compressor itself is also turning since it's directly driven by the engine and doesn't have a clutch (if my information about the car is correct). The two wires you mentioned should connect to the control valve at the back of the compressor.

It's possible that the compressor is stuck at minimum displacement and therefore, not pumping anything, due to a faulty control valve, which can be replaced separately. Or the compressor itself could have destroyed itself internally if it was run with a low charge and/or not enough oil.