Another ac thread

[iceman]

Ok that’s a good sign. Really no exact target, the baseline numbers I gave will indicate a correct charge and clean evap and condensing coils, with good air flow across them. Not sure which system you have but when you say thermistor I’ll guesss it’s a thermostatic expansion valve (TXV). These have a capillary line with a bulb on the end that attaches to the outlet of the evaporator. The bulb has a cross charge of refrigerant in it so that when the outlet line of the evap coil gets cold, it closes the diaphram in the TXV thus reducing refrigerant flow and cooling capacity. This exact same thing happens if the low side coil is dirty- Low air flow does not let the refrigerant “grab” enough heat from your cab,thus lowering the temp of the refrigerant and causing the txv to pinch off. In a case like this no amount of adding refrigerant will help except to cause the compressor to shut off on high head pressure sooner. Most important thing is keep both coils clean for proper airflow and your system will work as intended.