I have changed the A/C to R-134R.

What should the low and high psi be ?

I was told around

Low: 50
High: 250

I used a 30lb bottle and the only way to get the high to 250 psi was to fill the low to 105 psi.

Is this to much ???????

Also when I shut off the engine should the a/c make a whistle noise. It has done this for the last 4 months when I had R-12 in it with the psi at 50 low and 250 high...

All the other cars I have worked on never whistled when you turned off the engine when the a/c is running

Thanks in advance

 

I would call an A/C shop to find out about the PSI's. My 88 F150 I just converted to R134 makes a hissing sound when turned off. I would guess it's just the pressure in the high side slowly diffusing into the low side to obtain equilibrium. As long as you are not losing refrigerant, and the truck is cool, I wouldn't be too concerned.
Good Luck

 

The best way to ensure the system has a proper charge is to use a measuring device . For instance if the system calls for 2 lbs 8oz ...If you start off with a 30 lb cylinder deliver enough to approxiamte the weight . Shops that deal with A/C work use a system that delivers whatever the tech tells it to . R134a pressures will be much higher than R12 , but the pressures also vary some with the outside temps .
Paul

 

Watch out for that "whistling" sound upon shutdown...if it's coming from the vicinity of the glove box, there is a strong possibility it's an evaporator core leak.
Ed