2006 Tacoma Heater issue

Hey guys. I have an issue with my heater. At an idle it blows cold. When I'm driving at 2K rpm or higher it warms up but still isn't warm. Temp gauge is in the middle and doesn't fluctuate at all. Ive burped the system 3 times, changed the thermostat, checked heater core flow. Both heater core lines are warm.
Running out of ideas! Any help would be great

 

Sounds like the air isn't being directed through the heater core.

Have you checked all your fuses?

Have you checked airflow from vents at each circulation option?

 

What fuses would be related to the heater? Yes i have checked airflow. All functions work as they should. Temp also works as i can watch the motor turn all the way when i switch the temp dial

 

Just thinking there might be a blockage to airflow through the heater. If your temp is sitting steady in the middle that's where it should be so my guess is the issue is in the cab.

 

Changed out the water pump. Thought it might be weak at an idle. No change! I am lost!! Could it possibly be a head gasket? It runs perfect. No water in oil, no unusual pressure in cooling system with cap off..

 

Make sure that you have All of the air out of the system.

From what you have all ready stated the only suggestion I have would be the heater blend door is stuck on the cool side.

 

Ill burp it again. I can watch he blend door open and close when i turn from hot to cold

 

Did you check heater core flow by disconnecting the lines and flushing through it? I believe both lines will get warm even if it's blocked and not flowing through.

 

yes i did that. it flows perfect.

 

Be sure you have enough coolant and there is no air in the system. Check the cabin filter

 

Did both. New filter and burped 3 times

 

That pretty much rules out everything I know of. Are you watching the blend door move or just the actuator? I didn't think you could see the door since its buried in there. Maybe the door broke loose from the actuator and isn't really moving? Or the heater core is failed internally and bypassing the heat exchanger portion and just returning to the block? Neither of these 2 things are easy to check or fix is the problem...

 

I'm having almost the same thing happen. Mine will blow hot air above 1k rpm's but not at an idle. If the temp is around zero or colder I can't have the fan blowing full bore or the air will get cold even around 1.8k rpm's. Had the system flushed a couple times including the heater core. Mechanic said there was good flow through the heater core and really didn't have an idea what was up. They claim they also checked the water pump and it was good.

They seemed pretty stumped and I definitely am.

 

When i have the heater off both heater core hoses are very warm. I crank up the heater and it blows warm for a sec then cools off. As it cools off the lower heater core line also cools off. I have flushed the core twice now and seems to flow good but seems like a heater core issue! Any ideas to flush it better? I just used a water hose and ran through both ways

 

is your engine coming up to temp even at idle? This sounds like low coolant. I know you burped it several times tho. Good flow is good flow. Hows your thermostat?

 

Brand new OEM thermostat. Brand new OEM water pump. Engine always at operating temp. Coolant is topped. Burped it again last night, no air present.

 

Maybe you have a water pump issue... Not moving enough water.

 

Just a thought...have you checked to see that the A/C compressor isn't running and pumping colder air into the system? It will run on defrost, might be a switch problem that isn't letting it shut off on just heat.

 

Would that not cause an overheating issue? If the temperature gauge is sitting dead centre then it seems normal; that's where mine sits all the time, winter and summer.

 

Hey OP can you provide some details on the truck?

Year, make, model, odometer, 1st owner? Etc?