The system works, so i know its not under or over charged, its a sensor of some sort, because if it was trying to blow cold air it would be warm, but this air is HOT as it can get, like heater is stuck open. but its random, i can get in car and hit auto, and its ice cold one day, and next day, it can push air out, and as the car wams up , the hotter the air gets, i know when i hit the auto button, the compressor kicks on, like some valuve is stuck shut or sensor is not working properly.As many have stated on these boards, monitoring ONLY the low side does not ensure proper charging of the system.
I just did this this past weekend when I changed out the Compressor and Condenser Coil. Here's what you want to do.
Go to Autozone and rent a set of A/C Gauges ($200). When you return them you get your money back.
Start w/ Car off
Hook up the yellow hose so that it loops back on itself (essentially closing it off and preventing anything from getting into the system).
Close your Blue and Red Gauge valves
Hook up the blue line to the Low side port and the red line High side port. The connectors are meant to be pushed on. When you want to take them off you pull back on the quick release and remove them.
With the car still off, take note of the static pressure. There is a chart that you can use to figure out what the pressure should be. Also, this pressure should read the same on HIGH/Red Gauge and LOW/Blue gauge. This is b/c at this point the entire system *SHOULD* be equal.
Link: http://www.hantech.com/support/documents/H...ratureChart.pdf (if link goes down at any point, do a Google search for 'r134a tables')
1st column is the temperature degrees in F
3rd column is the PSI for 134a.
Example: If it is 85 degrees out, your static pressure on both HIGH and LOW lines should read 95.2 psi.
Once you can establish that the static pressure is good, it's time to turn on the A/C to the MAX setting (leaving the windows or doors open).
First, check to see that the A/C clutch engages and stays engaged.
Second, notice the pressures on the HIGH and LOW sides of the gauge set. The Low side should stay somewhere around 35-45psi. The High side (as a general rule) should be about 2.5 times the temperature. So, using the 85 degrees F as an example, the High side should be around 212-213 psi.
If the pressures are lower = System Undercharged.
If the pressures are higher = System Overcharged.
Either one will give you less performance for the COLDNESS of your A/C.
Post back with your findings.[/b]