AC cooling problem...gauge reads too high??

[shocker91]

i have been searching and reading related posts however I haven't found the right match. On my '91 EB which has been converted to 134 I've noticed the AC starting to get warm. From the various posts on the forum I purchased the Autozone 134 can and attached pressure gauge. I put the gauge on the proper attachement and found that the gauge read up into the "red" zone of high pressure. I'm looking for advice on how best to proceed and whether and how I can do it myself to save money on my hih mileage explorer.

 

[Glacier991]

A/C system pressure (high side or in your case low side) is read with the system operating.

 

[cifer]

I got the can for my gf's car, and was confused when I encountered the same thing you did. But if you grip the connector on the hose, and push down onto the AC port, it should give you the correct reading. It seems that as you hold down the button on the can to charge, the connector gets loose and pops up. Just be sure to stop charging every once in a while, push the connector onto the port, and read the guage again until your charged up.

 

[shocker91]

I did have the AC system operating and on high-cool when checking pressure. I thought I had a good connection with the gauge only because I recall having some trouble initially with the "snap on" connector. Per Cifer's point I will try the pressure gauge a few more times to see if I can get an accurate reading. If I find the high pressure where does that point me?

 

[gearz]

Was the compressor on the whole time you tried charging it up or was it cycling on and off? If your refrigerant gets low enough the pressure switch will turn the compressor on and off and will prevent the refrigerant from entering the accumulator efficiently and the gauge will go up into the red zone each time it cycles. Mine did that untill I jumped the switch which will keep the compressor on all the time--then I was able to put a full two cans in mine which now works great and has been for the last month or so since I did it. Don't forget to restore the switch when you're done.
Good luck and hope this helps.

 

[shocker91]

With all of your help I was successful in getting two 17oz. cans of 134 into the system with the gauge now reading in the "full" yet I am not seeing any significant change in cooling. It appears that it blows a bit cooler than it did but it is not where it needs to be in the heat of the day. The compressor seems to be working and the lines that should be cold are cold (not sure if should be colder) and vice versa...what is the weak link and the component most likely not holding up or ready to fail?

 

[Glacier991]

To start out, I am not a fan of the kits such as you used. A gauge set is a far more worthwhile investment and can help diagnose the system to boot. I'm concerned that you may have overcharged the system... 34 ounces of 134 is nearly a full charge - and we don;t know what the system condition was prior to the addition. With a gauge set we could have a better sense of the operating pressures on both high side and low side... in theory the pressure (in lbs) on the operating low side will roughly equal the temp of the evaporator. The myth on the kits is that the charge is a refrigerant system is like putting air in a tire.... it's not that simple.

So, my first suspicion is that the system is overcharged, which will flood the evaporator and prevent proper cooling. From a mechanical perspective it is possible you have a partially plugged expansion valve, however that will usually show up as an excessively low, low side and a high high side.

To tell you anything more would be only wild guessing. A gauge set would tell us a TON more.