At how many psi should the low side be running?

Answer 1

the psi on either side, high or low, is determined by temperature. the low side is the inside reading and the highside is the outside. To check if your psi is correct you need to get a temp conversion chart and see if the pressure, when converted to temp, matches the temp in the house at the return. Since that is the air temp before being (air)conditioned or the heat being removed. you can find a conversion chart in refrigeration books in the libary or you can go to a refrigeration supply store and ask if they have any. the'll probably give you one but here's some fast checks: the hotter the house the higher the psi. house temps between 70-90 degrees you're looking at pressures somewhere between 65 to 85 psi. if you're there, then you're in the ballpark. but your highside needs to be in the ballpark as well or you have got a problem. a high head pressure (highside) and low suction (lowside) can mean a restriction in the metering device, poor airflow over the evap coil, dirty filter and more. and high suction low head can mean a restriction in the condenser coil and more. meaning you have to look at both not just one. rule of thumb for reading highside is 30 degrees above ambient temp (outside temp) if your unsure if its right, double check by taking the temps at the return and the closest vent to the FAU you should see a 18-22 degrees difference. hope this helps. >>>>> It depends on what type of refrigerant you are using. The answer above is for R-22.