hi guys i just bought a 99 ram 1500 5.9 4x4 and everything works great but the AC compressor will not cycle on or off . i have checked the relays and fuses and it still will not kick on. kinda lost on what to look for next . any help would be great

You are low on R134A. And I hate to say it, but, the evap core in the HVAC box is most likely leaking since you have a 99. And without the proper equipment and know how. If I were you, I'd take it to an AC shop. If for nothing else but to just find out where the leak is.

i have put a test gauge on the lo pressure ac line and its reading fine , but it will not take any refrigerant, i think thats because the ac isnt cycling.

Check Hi and Low pressure cut out switches.

where those at?

Low pressure switch is on the receiver/dryer, high pressure switch is near the compressor.

Service manual in the FAQ/DIY section.....It will give more details and help identify components.

The low side will read fine when the compressor does not engage. Like I said, without the proper equipment and know how. Some one could get hurt. AC is not as easy as it seems. At least get the Haynes AC manual and read.

figured out y the low side was reading high was because the valve was not letting any refrigerant into the system. i got the valve cleaned out to where it will allow refrigerant into it and the compressor started kicking on and off, Now the system was reading low so im gonna pick up a recharge kit and fill her up .

Glad you figured that out. But it obviously has a leak if it's low. Please wear gloves and eye protection.