No heat when ambient hits 10 degrees F or colder, ( TODAY IT’S 40 degrees F and I get good heat.)
2.5 v6 2000 155k Cirrus . My heater core is open, I can blow through with house water pressure or even my mouth will blow through heater core either way. Heat output at registers at full hot engine is 100 degrees (at 40 degree F ambient.) I replaced stat with a Mitsubishi 180 factory part just in case,,prior one was aftermarket 180. Stat change made no diff in temp output. Mitsubishi/Chrysler or aftermarket do not list a hotter stat available. Say 190 degree
The coolant hose supplying heater core gets hot ,,such that I cannot hold my hand on it very long, the return side I can hold all day long. I cut the return hose and put it into a clear gallon jug. At idle no flow, when revving it will squirt a little bit every time you rev it to like 3000+ rpm. ( I can blow through the engine) using the other end of the cut hose and blow coolant into the gallon jug without any problem 1 good breath = (about1/2 to 3/4 of a quart ) heck of a lot more than revving the engine up to 3K 25-30 times.
the water pump was replaced two years ago FOR mtce reasons only when I did timing belt replacement at 110K,,now it has 155k miles.
have you heard of any issues with 2000 Chrysler cirrus LXI with 2.5 v6 Mitsubishi engine.
I have a 1999 Cirrus and replaced water pump and timing belt and it's just fine, register output is 140.. I tried a Chevy Blazer 3.4 v-6 vent register temp output at 170 degress at 40 ambient

the water pump was replaced two years ago FOR mtce reasons only when i did timing belt replacement...at 110K,,now it has 155kmiles.