2006 Tacoma Heater issue

you are running out of things to replace. Soon you will fix it.....

 

How is the airflow coming out of the vents with the fan on? Sufficient, or slow?

 

Maybe, it depends on how much water is getting moved. But that isn't the issue probably as he stated that it is OEM new, along with the new OEM thermostat and he has good flow through the heater core.

This has to be either the blend servo or air in the system.

 

its a 2006 Tacoma 4wd 180,000 miles. 3rd owner i believe. 4.0 V6. I have no clue what else to do

 

Air from vents is strong. I can watch the blend door fully open and close when i change the dial by watching the servo arms operate. Is there a better way to flush the core? Seems like the heater is pulling heat and it cools off right away like there isn't enough flow or something

 

That's how mine is. Dealer said they used compressed air through the heater core to try blow out a blockage. They tried three times to flush the system with coolant and compressed air. They said flow seemed fine when they flushed it with coolant the last time. They said water pump seemed fine but I question if they ever checked it.

Heater worked fine all last winter. Had the thermostat replaced this summer. No issues with the cooling system until this winter. Two places would have had to have left air in the system, one place after three flushes, for air to be causing this.

So I can't help you, but I am going through the same thing.

 

No heat is basically always a clogged core or a failed open thermostat. But...

How does the air flow in the cab in order to get heat? Does the fan push air through the core to warm up or does it pull. And regardless of how the blend door is sitting can the system get enough air to blow strong without passing through the heater core on the inside.

Is it possible that a bunch of leaves and shit has bunged up the heater core inside the cab and insulated it so even with good coolant flow there can be no heat exchange on the air side?

What about using compressed air to blow out the core and clean the vents inside the cab? My 2005 did not come with a cabin air filter and being the 3rd owner means you don't know if the previous owner(s) left the truck parked under a tree that was always dropping leaves or needles or whatever.

Juuust thinking out loud here.

 

Sounds like you have a blend door not operating correctly in the dash. Not sure if it's a vacuumed operated door or mechanical motor but that's where I would start.

 

I agree with you, heater core seems to be the issue. Sounds like both lines warm up, then the airflow cools the core as expected but it's not getting enough coolant flow to stay hot. If you turn the heat off, then let it sit and run a bit, then switch back to heat and it blows hot again for a second, that would confirm it. I would be scared to put too much air pressure on the core and causing a leak. Would go both directions with the water multiple times to try and work out a blockage. An internal failure is still possible which would cause the same symptoms.

 

Yes i turn the heater off and both lines warm up. Then i turn the heater on and the exit line cools off. Gets pretty cold actually. I turn the heater back off and it warms right back up!! Im just worried about putting too much air pressure or water pressure to the heater core and blow it out. I really dont want to rip the dash apart to replace the core, its a huge job!!

 

Could one of the lines between the block and core be clogged or restricted? You said the core had good flow, but the symptoms point to low flow.

 

Disconnect the hoses to the heater core and blow it out with compressed air. Then fill it with either CLR or vinegar. Let it soak for awhile and flush it both ways.

 

My 2007 4.0 did the same thing 2 years ago. Heard a slight gurgling noise from dash area and the exact same issue. Twice had to add coolant to the resivior bottle about 12oz. Checked for leaks never found one. Checked water in oil nothing. Never found issue and no problems since. Check the resivior. Sorry could'nt be more helpful, but it did work.

 

Had a friend with a Jeep with this problem. He had a back-flush tap installed in a heater line, and when pressure was run backwards through the core, lots of rusty crud blew out the inlet heater hose.

 

Ill try flushing it again with vinegar

 

Flushed it out with vinegar. nothing came out. It was all clean!! Same issue... Completely out of ideas

 

Sounds like you must be getting some cold air into the system somewhere between the core and the vents IF the core is getting hot, AND the blend doors are operating properly. Sounds like it might be time to bite the bullet and have the dash gone into to get to the core and all the vent ductwork.