AC cold then hot

1998 jeep cherokee 4x4 limited 128k. AC gets cold rather quick, but every ten minutes or so, the AC will blow hot for 10 minutes, then return to cold air again. I thought that it needed freon, so I hooked up a guage and freon to fill it up, but it reads overcharged on the guage. I live in las vegas, so even ten minutes without AC is miserable. Going on a trip with kids and want to make sure AC is working all the time. any ideas are helpful. thanks

1998 jeep cherokee 4x4 limited 128k. AC gets cold rather quick, but every ten minutes or so, the AC will blow hot for 10 minutes, then return to cold air again. I thought that it needed freon, so I hooked up a guage and freon to fill it up, but it reads overcharged on the guage. I live in las vegas, so even ten minutes without AC is miserable. Going on a trip with kids and want to make sure AC is working all the time. any ideas are helpful. thanks
If your over charged I think a safety switch is shutting off the compressor. Look at the clutch on the compressor is it shutting on and off with the temperature change.
Depending on your tools charge enough to get a good sweat on the suction line on a hot day.
Get a loaner set of gauges and check both suction and discharge pressure.

Once you have the pressure correct, let us know if the problem continues.

If it does then there may be a vacuum leak that is causing the changes in the system.