Originally Posted by NewShockerGuy
By bumping it to 35 psi wouldn't I then run the risk now of overfilling the system since I put the correct weight in? How does one know what range is best... Would it be better to add it and then keep waiting a little bit and if the temp STARTS to go up then relieve some and vent some of the excess r134a out until the temps lower again?
Thanks again for all this info!!
If you look back at the charts I posted, the Normal Suction Pressure or Low Side Pressure chart shows a range based on outside air temperature and humidity. Along the bottom of this chart (horizontal line) you'll see the outside air temp and on the right vertical side you'll see the corresponding pressure range compensated for humidity.
You said the temp was around 70 at night when you filled it. Humidity is typically higher at night. So if the average humidity was 50%, the pressure would be around 30 -35 psi.
I'd recommend checking it during the daytime hours. First check your local weather channel (online) and find the current relative humidity for your area. Check the current outside temp with your thermometer. Then look at the low side chart and find the optimal pressure base on the above information. Warm up your truck and then jump the cycling switch so the system stays on. Set your idle speed to around 1500 RPM and look at your pressure readings (low and high side) and write them down. Check the air outlet temp from the dash vents and write that down. Then reference the charts to determine the optimal pressure.
For example say the outside temp is 80 and the relative humidity is 30%. The corresponding low side pressure would be around 30-35 PSI. If the humidity was 60% it might be as high as 45-50 PSI. The corresponding high side pressure would be about 155 PSI at 30% and 230 PSI at 60%.
Bottom line, get the system to the lowest reading for the temp and humidity given and with your thermometer in the dash vents slowly add a little more, watching the dash temp. If it starts to go up, bleed a little off. If it continues to drop, add a little more, not exceeding the max shown on the chart.