2003 Cadillac CTS 6 cyl Two Wheel Drive Automatic 92000 miles
I have a 2003 Cadillac cts. I replaced my water pump and thermostat. I still don't have heat. When you first turn on the heat it blows warm for a second then goes cold. Any ideas why it's still blowing cold air?
If it does blow warm shortly, it could be low flow through the core either by a plugged core or restriction to it. If you can get to the connections and disconnect, you can try compressed air through it. Or if you can determine which line is outlet, disconnect it and when started, check the flow. Your heater control valve should have vacuum at the line when heat is requested.