Q: Air conditioning blockage pressure - 1988 Mercedes-Benz 300TE

asked by on September 16, 2016

My air conditioning isn’t working right. Its summer now, so I need to get it fixed. I think there might be some kind of blockage in my AC but not sure where. I cleared out the system and vacuumed it down to ~29hg. There's only 12 ounces of refrigerant in it, and I’m getting 45/320 psi lo/hi. That’s only a third of the recommended capacity for r134a refrigerant and 28 ounces is recommended. So why is the pressure so high after 1 can? I think it’s a blockage but not sure. Could something else be causing this? I’m clearing the lines of air before I start. The vacuum held fine for 30 minutes after I shut off the valves. Do you have any idea what might be wrong and how I can fix this?

Hey there. The condenser is blocked or the expansion valve is stuck causing the problem. Make sure when testing you have proper air flow across the condenser. If the fan clutch is not working good then the pressures will be too high. Check the fan clutch if it is at full flow. If you would like to have this checked, a qualified pro from YourMechanic can come to your car’s location to inspect the air conditioning and proceed with the proper repair.

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