you might want to check and see if the heater core is bypassed
Heater core changed three years ago,I changed Thermostat Heater still blows cool air.
you have an airlock
You have not bleed the air out of the system after you installed the t-stat, causing the heater not to work and the engine to overheat. Use a coolant filler that screws into the radiator and get the air out
I have a 1991 190e 4 cylinder with the same problem - in cold weather the engine does not warm up. I know that I have a head gasket leak due to oil in coolant. I changed the thermostat but no improvement. I suspect the head gasket leak somehow affects the working of the thermostat or circulation of the coolant.
If it still blows cold when it is at running temp, check the engine thermostat, its probably stuck in the open position.
control fuse blows when you plug thermostat to base controlling a gas pack unit
If you KNOW for sure that you installed it correctly Then you probley have a air pocket in the water jacket / air locked.Run engine with radiator cap off for a while,being sure that the engine does not over heat/ watch Temp. Gauge.Add coolant as needed.
why do you want to. This would be a terrible idea as the 2.2 engines have head gasket issues. When the gasket weakens, the engine will start to overheat, and without a thermostat you wont know until the gasket blows and you ruin the entire engine. So you "can" run without a thermostat if you feel like blowing your engine.
On the 3.4 V-6 Chevy Malibu the thermostat is located at the rear of the engine. The exhaust cross over pipe that goes between the exhaust manifolds makes the thermostat housing hard to access. The easiest way to change this thermostat is to first remove the exhaust shield and exhaust cross over pipe, then the t-stat can easily be changed. After changing the thermostat, be sure to bleed the air from the system, look for bleeder screws and run heater until air blows warm.
That is normal, It is a thermostat
Bad Thermostat
Check coolant level Perhaps thermostat is not opening to allow coolant to circulate through engine and heater core