I had a broken vacuum line for 1st 2 winters I owned my 97 Grand Cherokee Laredo ZJ 5.2L (only defrost worked, no vet air or cruise); finally got it fixed over summer. Heat worked great, easily made the cabin into a pizza oven. Then this morning on way to work, no heat only cold air blowing out of the vents; temp outside was in the 30's. Jeep's temp gauge got halfway up by time I got to work but still no heat. Haven't got a chance to look at anything yet, where should I start? I have read an open thermostat, bad heater core, or a bad blend door or blend door motor. What diagnostic steps should I do to eliminate the easiest things 1st?
Went out this morning, warmed truck up for 10 minutes then got in for a little trip around the block. Small puff of warm air then cold.....then after accelerating from a stop sign warm air returned. Temp gauge had been almost to 240. Took it right home and popped hood to find an antifreeze shower had soaked the entire front 1/2 of engine. Needless to say the radiator was empty. Gonna let it dry out a little and see what I can see; obviously sounds like something was plugged
Replaced water pump and the heat has returned, no leaks. However, a new problem has arisen which probably has nothing to do with the previous. Started Jeep up this morning to let it warm up for a few minutes, put it in reverse backed up 15 feet and it stalled. Cranked and cranked and cranked until it finally started but wouldn't keep running unless I was feathering the gas. Managed to get it back in the garage and get to work via other means......so where do I start to diagnose this issue?