My wife has a 98 grand marquis and just recently when the ac is on the car jerks pretty bad going down the road and the air will freeze you out. I started thinking maybe the system is low therefore the compressor is kicking on and off more ofter.

I have one of these low pressure ac gauges that you can buy with the r134and I hooked it up last night and it showed right at 25 on the gauge. I went to the parts store and got a 12oz can and put it in and it raised it to about 35 on the gauge.. The car is still jerking on the highway.. here is my main question.

On the gauge it has a dial and it says to set the dial to what temp it is outside. So when i move it to 85-110 degrees it shows i should put in around 50-55 on the gauge. Does this sound right?

 

Yeah. You point the arrow at the outdoor temp and the air has to be on max full fan turned all the way down. Then add a little at a time til its between the lines. Not sure if that's the surging problem but kinda makes sense. If its low the evap will be too cold then will cutout on low pressure.