I’ve charged my system, and for some reason, my AC is not performing properly. It’s 74° and these are the numbers:

Seems to me that the more I add, the less it cools in the cab. Best temperature I got was 55° or so. The settings are at MAX in the cab. I did reference the FSM charts, but no luck. Everything is brand new. The refrigerant used was R-134A from a 30 lb cylinder. If anybody can help, it’ll be greatly appreciated! Thank you. (1996 Dodge RAM 2500 V8)

 

Having too much is just as bad as not having enough..... However, for the current temp, your pressure look spot on. Is the temp door closing all the way?

 

By “temp door” you are referring to the blend door correct? The cable controlled door? If so, yes. But how can I verify?

 

Those charging numbers look good, however, the cooling temperature inside the cab is definitely high. On hot summer days here in central VA, I've gotten my standard cab temperature down to about 40 degrees - feeling like you could hang meat in there. Did you vacuum out the system fully before recharging it?

 

Yes. The system was evacuated for 2 hours, and held.

 

I think there is a procedure in the service manual for adjusting the cable operated blend door..... But, that's a poke and hope kind of thing. If you have a bore scope, might be able to snake the camera in there, and have a look-see.

 

Do you have a scale to measure the tank as you charge the system? The A/C system on my '96 Dodge Ram 2500 standard cab truck takes 2 pounds of R-134a for a full charge (you should have a sticker under the hood on the radiator support that shows the R134a charge for your truck). When I charge my truck, I usually rev the engine to about 2,000 RPM until its fully charged, then read a thermometer I stick in the main output duct to get a reading on the inside cab temperature.

 

Too much refrigerant will keep your system from having a pressure drop. That's what causes the refrigerant to give up heat. It's been about 50 years since I was trained on a/c systems so I can't recite the rules of thermodynamics in play here, but you need a pressure drop to cool. Some years Ma Mopar used an orifice tube and some year an orifice block. Is your clean?

One question, why does it look like engine coolant on your gauges? As expensive and delicate as they are, I keep mine pristine.

 

Look up the terms 'subcool' and/or 'superheat' in google. You can navigate your way from there. I use 'subcool' to do a partial recharge on 'ol picasso ('96 Ram 1500/5.2) myself. My hi press shrader valve leaks, so about once a year I have to recharge instead of just sticking a crobar in my wallet n replacing the valve. Hope it helps.