My ac compressor clicks on and off about ever 5 seconds has anyone had this problem before?

 

Sometimes they're supposed to do that. It might not be a problem.

 

Possibly low on refrigerant and cycling on low pressure switch.

 

Yup. Low freon probably.^
fix it now......even replace compressor preemptively....before it fails. Freon carries oil....low freon means low oiling. It may work....but if keep adding freon eventually whole system will need replace after compressor fails. Extra $250 is cheap insurance to do right first time. I dont like repeating repairs

 

My suggestion is to recharge with a kit that includes refrigerant, oil, leak-stop, and leak-detector dye. (something like this: http://rechargeac.com/products/our-b...c-recharge-kit ) You can then determine if the system is still leaking and if so from where, and the next step(s).

In my opinion, there's no reason to invest time and money in a new compressor on a 20+ year-old truck if it's not needed, and it's a *whole* lot more work than recharging and seeing if that does it.