EdJennings

A few years ago this car had sat unused for a couple of years. It’s 21 years old, and still only has about 72K miles. When I put it back in service, I charged the AC. It was pretty much dead. Anyway, I was able to add a couple of cans of 134a in the system, and it has worked well for several years. I decided that I needed to check the charge as I didn’t think it was quite as cold as it should be. Anyway, I got everything hooked up, and on the suction side I was reading 25 psi. Needs to be at least 30-35 psi.

For some reason I cannot add Freon. The clutch is turning. It feels like I’ve gotten a smidge of Freon in the system, but it’s still reading 25 psi. System is blowing fairly cold air now, but I didn’t test it before and after. Usually if the system won’t take gas, the compressor isn’t turning. Anyone know what the problem might be.

KevinH2000

I am not an AC system expert, but my understanding is that it may be necessary to evacuate the system before attempting to add refrigerant. I understand that most auto parts stores sell DIY refrigerant kits, but they may not be adequate in all circumstances.
As you noted, the car is 21-years old (mine will be 20 soon) and it's possible that a defective component is the cause.

slammer111

The bigger problem is that you have a leak. Probably want to get that checked out. A properly working AC system should have basically 0 refrigerant loss. I've never had to charge my system.

In any case, I'm pretty sure refrigerant can be added through the low side in a system. Maybe the can doesn't have enough pressure?

C230 Sport Coup

If it's cold out it won't want to kick in.
In my case I discovered I had to warm the cans in a pot of hot water.

KevinH2000

The video I linked suggested holding the can upside down. This would allow the liquid portion of the contents to flow first rather than the gas portion. But, as Slammer pointed out, finding the leak is job one.

EdJennings

I tried the van upside down with no apparent difference. As to the “leak”, this air conditioning system was last serviced in probably 2016. So, it has seeped probably less than a lb of Freon in 8 years. I was an industrial maintenance manager for more than 30 years. The mechanical seals used in pumps and compressors are not 100%. They will successfully hold fluids and gasses for a long time, but some leakage is going to occur over time, though it may be at the molecular level. The system is working real well at the moment. But, it is only about 85° here in central Alabama. I’ve been using one of those kits to recharge for 20 years or more. I’m not 100% confident that the dispensing working properly. I have a regular set of gauges that I’ll hook up next time and see if there is a difference.

EdJennings

The low side of the system is a suction. The can doesn’t have to have any pressure.

slammer111

Are you sure about this? My understanding of any AC system is the gauge pressure is still positive on the low side even when the system is running.

EdJennings

well, I guess that’s true. There is a pressure on the low side. But it’s also true that when the feed valve is open, the pressure drops to nearly nothing at lest momentarily.

C230 Sport Coup

To be certain its not flaps any halfway decent scanner such as iCarsoft will tell you pressure and
temp of freon. I'm going to be checking that myself, since today, I tried to turn on the AC and nothing.
Might just be a flap, I don't have AC guages, at least not without buying it ie renting at Oriely, but I check live data.