2000headssuck

Specific to the following, applying some compressed air to my vacuum line (the one that ends at the battery) must have actuated a door (2, or 3, as I can see door #1 moving when I turn the heat dial on the dash from cool to hot) ...

2000 XJ 4.0 Purchased 2 months ago, 149K miles

Replaced the following:
Radiator
Coolant overflow tank and hose
water pump
thermostat (not the housing)
power steering pump
upper & lower coolant hoses to rad
cylinder head (clearwater)
intake manifold (was broken where I couldn't see it towards the firewall, luckily Advanced Auto Parts had one ready for me


So, maybe instead of getting to the point you decide to replace your core, try brute force with an air compressor into the vacuum line that actuates the door(s). Admittedly, I do not know which door was affected but it turned my "heat" from something 2-5 degrees warmer than outside air to what I think is about 75% of stock heat. Remember, by applying air pressure to this line, you'll rev the engine...so don't freak out or get scerd haha...kidding but worth noting.