What would make the heater in a 1998 Cadillac Catera not blow out hot air?

did u ever discover the problem?...My catera is having the same issue... Thx

Try taking the cap off coolant tank, and running enging till all the air bubbles come out, as it sounds like you have a air lock in your cloolant lines.

Water control Valve, very common on catera's. about $90 dealer only part.

in my case it was my oil cooler, it had blowen a seal and was mixing my oil and coolant, the oil cooler is located in the valley of the engine, and installed would cost almost $1100.