97 Jeep Cherokee, air conditioning compressor cycling on/off and weak cooling

I have a 1997 Jeep Cherokee with factory air and about a year ago I noticed that the air was getting wimpy to the point where it just wasn't cooling anymore. This year I went to the local auto parts place and picked up a R-134 kit to recharge my system (figuring it was low and had a small leak). I hooked up the gauge that comes with the kit and read the value off the low pressure side of the airconditioning system and (from what the kit instructions say) the gauge read about 45 psi (which is supposedly good for most low pressure side readings - they say that's normal). No matter, the compressor regularly turns on/off - about 10 seconds on and about 10 seconds off - - - all the time. I just about put in some R-134 and then figured I better get on the news groups to see if this is normal or not with this rig. The air is just lukewarm - not quite cold, not quite warm either on an especially hot day today.

What do you guys think? The system low pressure reads right (doesn't surpass 45 psi and just sits there) but it's not getting cold either. What's the correct pressure reading for this system and what do you suspect is wrong? The vent system is correct (I checked that). Thanks in advance for helping out, guys.

The gauges in those kits are worse than useless.

What is the pressure with the engine off? What is the ambient temperature when the above reading is taken?

What is the low side pressure with the engine running at 2000 RPM and the compressor engaged?

What is the high side pressure with the engine running at 2000 RPM and the compressor clutch engaged?

Is there any mention of "sealer" on the can(s) of refrigerant that came in your suicide kit?

If the compressor is cycling on and off, pressure must be changing in the system -somewhere-.

BTW, odds are that it is the evaporator leaking. Figure $700+ to replace.

The pressure should be read with the compressor running. If the compressor is cycling on and off then you can't get a good reading. The system cycles off on low pressure so it also seems unlikely that your system is actually staying at 45psi steady... Perhaps you gauge isn't working or isn't connected properly.

Steve B.