A/C and Electric Fan

Whenever i have my AC turned the AC pump only engages the clutch for about 3 seconds and then kicks off. also the electric fan runs at the same intervals of about 3 seconds on, and 10 seconds off. i opened the electric relay box and listened to those, and they seem to be working fine, its just that i cant get the AC to Functionally work. any info before i just try replacing my AC unit?

Low pressure...although the whole "on for a few seconds" thing is pretty normal for the XJ AC

the fan is tied to the a/c, so that is normal.

the a/c can cycle like that if it is low on coolant.

unfortunately, since you have a '99, if you are low on coolant it is likely a leaky evaporator core (it's a problem on the 97+ you can search for info on that).

i attempted recharging the system myself with on of those cheap little things from the auto parts store, and the pressure was definatly low, but it has not really fixed the problem at all... it still does the 3 seconds on, 10 off deal...

There is a built in cut off switch so you don't burn up your pump. Take it and have pressured tested and you will find your problem.

ok will do, thanks all

What you descibe is similar to what happened to mine. It was cycling on and off rapidly. Hooked up the guages to check the pressure and sure enough, everytime the compressor came on it brought the pressre on the low side down enough to trip the low pressure cut off. Took it to a mechanic to find the leak and it was in the evaporator. He wanted $1100 dollars to fix plus $360 for the part. I bought the part myself for about $150 at NAPA. Once I find a weekend to set aside I'll change it out and recharge it.

The amount the compressor cycles is also related to evaporator fan speed as well as refrigerant charge.
With the fan inside the vehicle on high and vehicle idling the compressor should almost run nonstop. It sounds as if your low on refrigerant, the low side should run around 35 psi. If the system was ever flat or opened and not evacuated before recharging all bets are off. Good Luck