ImaFungi

Hi All.

I searched and did not find this specific question for this particular car. I have a 05 Monte Carlo 3.8 liter that is blowing cold air when the heat is on, seems as though I can feel some warmer air blowing when I first accelerate, but once I hit cruising speed (55 -60mph) the air blowing isnt even warm. Since I live in MN and the current temp is about 5 degrees above zero I expect the car to take a little longer to warm up.

I have tried the following things.

Checked coolant level (all is good)
Replaced the thermostat and bled system.

Prior to replacing the thermostat the temp gauge would not come close to half way, following replacing the thermostat it would hit the halfway mark on the gauge and then fall back down.

It doesn't seem to matter if I have the defrost or vents on, just blowing cold once I am not heavy on the gas..

The hoses running to and from the heater core are both hot when at running temp. I had noticed since I bought the car, that when I start the car and turn & stop the car I could hear fluid sloshing around under the dash, but nothing is leaking inside or outside the car, this sound is no longer there so I am wondering if my heater core might be plugged?

oldchevy

If the heater core was clogged then one heater hose would be hotter than the other one. More than likely you have a bad blend door actuator.

ImaFungi

Thanks for the quick reply and idea! I was thinking the same thing with the hoses both being hot. If you don't mind another question, if the blend door actuator was faulty, wouldn't the air blowing not change from vent to defrost? The air stays cold wether its coming from the vent or defrost. Sorry if its a dumb question, but prior to this I have lucked out in regards to car trouble not including dashboard issues. Thanks again for the quick reply!

oldchevy

The blend door actuator has nothing to do with which vent it is blowing from. That is another actuator. Not familiar with the Monte Carlo, but some vehicles have 3 or 4 actuators.

ImaFungi

Thanks! I'll check it out.

billboyd

I think these are both the same actuator part number, but the blend door actuator affects cold to hot and the mode door actuator affects where the air is blowing, floor to defrost etc. I have a similar problem with my pickup but it is intermittant. If your car has temp settings for driver and passenger then there will be more actuators to check. Once you find them, you can generally put your finger on the bottom of the actuator itself and tell if it moves when you turn the temp control from cold to hot and vice versa. I have also heard of certain vehicles with issues in the control module itself or with the blend door being stuck in one position.

ImaFungi

I'll have to check it out, thanks! Sometimes I'll get warm air and then the heat just stops and blows cold again.

billboyd

I have the exact opposite problem with my truck. It will be blowing cold air and then all of a sudden stop and blow hot air. Bummer in the summer, but not an issue right now. The intermittent issue is my problem. I'm leaning towards a connection or solder joint somewhere, but just not sure where.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>

ImaFungi

OK, I couldn't take the cold any longer and brought car to a local repair shop to be checked out. They found a couple of things with the cooling system that needed to be addressed. First, I did have a leak in the heater hose fittings (elbows), not that this would cause me not to have heat, but I did notice that distinct sweet smell of antifreeze once in a while. The coolant would hit the hot engine and never made it to the ground. The issue with the lack of heat was caused by a plugged up heater core. I had the elbows replaced to the tune of $228.00 (the parts were $9.00) and the rest was labor. The back flushing of the heater core was $56.00. I thought for sure the lack of heat was going to be something a lot more involved, but thankfully it wasn't. Had the weather not been so cold I would have tackled all this myself, but a lack of time and a warm place to work on a car was my deciding factor to have a shop take care of this for me.

gasteffens

That's very common on that car, from what I have seen at work. Glad you got it fixed!