one test the service manual suggests for your water pump is to turn on your heater.
it may be a sign of something else but lack of heat also points to failing water pump.
not saying yours is kaput, but it is a good thing to know if the signs are present.
97 TJ 4.0, AW-4, Clayton, A.R.B., Highly polished HP30, Super 88
There are no shortcuts to any place worth going
91 XJ 4.7