Heater not working - beyond the obvious - please help!

Hey all,

I know this issue has been addressed and I've read several different threads on this topic but I'm still in need of help. 2004 Tacoma 2WD 4cyl.

I flushed the cooling system with the heater on high with a chemical flush solution from auto zone and replaced the thermostat. I flushed the system until the distilled water came out clear when I drained it (about 4 flushes). I burped the system each time by letting it run with the radiator cap off and gently squeezing any and all related hoses I could get to until no more bubbles came up. The hoses going to and from the heater core are warm to the touch when the engine gets to normal temp. There is a noticeable difference in temperature between the upper and lower radiator hoses though. Even after I replaced the thermostat (about halfway through all the flushes I did), the lower radiator hose doesn't seem to get very warm. The hoses seem to be in fine condition, I don't see any cracking or obvious spots where coolant would be leaking. There was a little gunk built up around the cap to the overflow, but I didn't think too much of it since its the overflow and the level of coolant in it before I got started was normal. The temp gauge has always worked, before and after I replaced the thermostat.

Any advice or other things I could check would be greatly appreciated.
Thanks!!!

 

Is temp rating of new t-stat same as the one that was replaced?

 

I'm not familiar with the 4cyl, it really sounds like you don't have any circulation. The heater hoses should be just as hot as the radiator hoses, with the heat setting all the way open. On my 02 6cyl the heater valve is on the firewall, with a hose going to it from both sides with a cable hooked to it. If you have something similar to this, it could be messy, take the hose off that goes to the back of the engine. That should be the return and fluid should run out of the valve with the valve open. This way you know if you have antifreeze circulating.

 

I'm not sure as I write this, but it does sound like the water is circulating through the heater core as it should. I think your heat control operates a flapper that allows the hot air in the core's fins to flow through the air ducts inside the cab. You might want to check that.

 

Sounds like you still have air trapped in the cooling system.

 

Your hose description is proper in terms of temp delta. Its what a radiator does. Reduce temp of coolant.

 

The lower radiator hose should be cool because the radiator cools the coolant before it enters the engine, so that's normal.

Have you revved the engine to give the water pump more force to pump the air bubbles out. On mine if I sit in the cab and rev the engine and move the heater control back and forth from cool to hot with the blower off I can hear a whoosh of coolant entering the heater core, so I know it's circulating. I do this with the radiator cap on.

 

Your cold hot actuator may not be working. looking from the passenger side, looking up under the dash in front of the center console, you should see the actuator move when you turn the temp knob from hot to cold.

 

Yes, check under the dash. Even though the dash gauge works, does the engine seem to warm up and get hot like it use too???

 

Try parking on an incline or raise the front of your truck up and see if that gets all the air out of the system.

 

Thanks for the responses! I'm not sure about the temp ratings on the thermostats... I see the heater valve on the fire wall, and from my understanding, the little cable activated lever on the bottom on that valve is supposed to move when you move the temp dial to hot or cold in the cab. That little lever is not moving so that might be the problem. I guess I'll replace that and go from there. I'll also check the hot cold actuator. I should be able to see that actuator without removing the glove box?

Thanks again for everybody's help! Taco brotherhood! lol

 

You can take the cable off that valve and try to move the lever by hand to see if it makes a difference. You can find out if the lever on the valve is binding or if it's the cable that binding.

 

Yes. The actuator is behind the radio.

 

here's something you can try. see if the hoses going to your firewall are hot. while youre doing this, check to see if the heater valve is working since youre going to be there anyways.

 

I had the same problem on my Jeep.
Turns out intake/return lines for the heater core were missing and bypassed, lol.

It could be something with the blend door, if it's not working properly you won't feel the hot air.

 

Good plan.

 

Update: the heater valve wasn't the issue. I took it off and worked the lever to make sure it worked. Then I put it back on and did not attach the cable part to it, put it in the open position, ran the truck, burped the system again and still no heat. The hoses to and from the heater valve and the return from the fire wall are hot. It seems that the air coming out now is a little bit warm, but definitley not hot. So, the cable not working that heater valve lever is definitely an issue, but what else could be causing the no heat issue now with the heater valve open? Could it still be the actuator? I need to research some about how to check and inspect the actuator.

 

door actuator is the only thing really, aside from the wiring involved unless its cable driven as well.

 

The cable that controls the outside water valve I believe hooks to actuator also.

 

Not trying to be a putz, but how sure are you that you've removed all of the air from the system? Sometimes it can be a little difficult or frustrating.