I have a 2000 v6 Ranger that my son drives and a 99 Mazda B2500 that my wife drives.

The heat blows luke warm in the Ranger and has for a couple of years.

The same problem started in the Mazda at the end of last winter. Getting cold again, so my wife isn't happy.

I have checked the heater core door motors, replacing the one on the Ranger and the Mazda appears to be functioning.

When you move the dial from blue to red, you can feel just enough temperature change to know something happened, but it isn't even warm.

Both vehicles have new radiators within the last couple of years. The Ranger after the heater issue, the Mazda before.

I put a new thermostat in the Mazda today, to no affect.

Is there a sensor somewhere? Something more to the door issue than a quarter turn to open and close it? I am at wits end. Even talked to a couple of mechanics and had tried anything they could suggest.

 

flush the heater core..start there and then make sure ALL the air is out of the system

 

I flushed the heater core out today, again. Did it at the end of last winter and didn't help either.

How do you get air out of the cooling system. Wouldn't that work it's way out just by driving/heating up.

 

no you need to take the rad cap off...start the truck and let it run with no cap for 10-15 mins or until it warms up completely with the heat on full blast..reving occasionally...im willing to bet you have an air pocket in there

 

do as stated above, and also record the temperature of the heater hoses before and after the heater control valve

 

I replaced the heater control valve last year. Could it be out again?

I cut a hole in the side of the box behind the glove box to see if the blender door was functioning.

It is opening and closing as I assume it should. There is hot are blowing when it is closed, but then it turns cold.

It feels like the AC is not turning off and the heat and air are battling each other. ( or could this be from the air pocket thing ?)

The AC is supposed to turn off isn't it, not just be blocked by the blender door?

The fan was pushing hot air for 5 or 10 minutes sitting still, but when I started driving it would alternate hot and then cool down significantly.

 

Ok, I have found out some more info.

I am getting hot air when only the floor heat is on.

When you turn the defrost on, the AC engages to dry the air? Also happens when you turn the heat to panel/floor, which is what my wife likes to use.

When you do either of these last to, the AC is overpowering the heat. Cooling it down to where it is barely warm today, and outside temp is in the high 60s. If the temp gets down in the 20s to 40s it just blows cold.

Anyone know a reason why the AC would be overpowering the heat? This just started happening last winter. Wasn't doing it before that.

 

the a/c compressor engaging is normal...runs in all positions except floor only i believe...all fords do that...try and get any air pocket out first

 

Yes. Found out the ac kicks in to dry the air for defrosting.

But it is not supposed.to overpower the heat. It should still blow hot but doesn't by the time it leaves the blower/heater box.