The HeaterTreater is an after market kit that solves heater and AC for the Jeep Grand Cherokee and Laredo. It is much cheaper than the dealership fix and is easy to install. For diagnosis and info, check out www.heatertreater.net or search eBay for "heatertreater".
Changing a thermostat on a 1995 Jeep Cherokee is very easy to do. The thermostat has two bolts holding it in place. Take the bolts off and remove the thermostat from the casing and replace with a new one.
The thermostat on a 1996 Jeep Grand Cherokee 5.2L is replaced by draining the coolant and disconnecting the radiator hose. The housing is then unbolted, the thermostat removed, and a new unit put in its place.