Hi everyone. New to the board and I need some help.

I've stumped myself and two shops with this problem already. The heater in my 99 Tacoma 2.7 isn't working properly (not a good situation in New Hampshire...especially this winter). The temperature gauge comes up to normal temp very quickly and then stays there, but the heater blows cold. Its not until I've driven for 45 minutes or so that it starts to throw some heat. The coolant level is very full and is very clean. The lever on the heater control valve is moving properly. The last shop I had it to said they probed the temperatures of the core inlet and outlet tube and they were normal.

The only other symptom is bad gas mileage. I'm only getting 17 mpg, without driving aggressively.

The only things I can think of is that coolant isn't getting hot enough but the gauge is indicating that it is for some reason. This would explain the bad mileage and lack of heat. The other thing that would make sense is if the coolant circulating through the core is somehow coming from the radiator and not the engine. That would explain why it is cold even when the engine is hot and how it eventually gets warm after extended use. No idea how that could happen though.

Anyone have any other ideas?

Thanks,
Tom

 

you could check your thermastat also check the heater core to see if its getting hot. its possible the heater control cable may of come loose.

 

Thanks.

The cable is working properly. I assume the T-stat is OK because the operating temp indicates exactly what it should. How hard is it to get to the core on these trucks? God...do I hate working under a dashboard...

Thanks again,
Tom

 

I'm not familiar with your truck but how hard is it to get to the heater hoses? Could you pop them off and run a garden hose through the heater core to make sure it's not clogged? It would be great if you could include the heater control valve. The cable moving back and forth may not be moving the valve inside?????

I would want to be sure water was indeed circulating correctly. The water would warm up by conduction but not throw off much heat if it wasn't circulating.