Heater extremely weak

Hey everyone, first post on here. My 2003 Tacoma’s heater got really weak. I can still feel hot air coming out of the vents, it’s just not very strong. Tried replacing the blower motor and that didn’t help. Any suggestions on how to diagnose the problem? I really want to avoid messing with the heater core as I live in Alaska and don’t have a warm garage to work in. Thanks!

 

Weak as in how much air is coming through the vents or the temperature of the air?

 

If you run the AC do you have the same problem?

 

Nope the AC seems to blow just fine!

 

Weak as in how much air is coming through. The temperature is warm, just the power is low.

 

What happens if you shift heat to blow out dash instead of floor?

 

Gotcha. Can you hear the fan roaring louder with each fan setting, indicating more air is moving (just not to the right place).

And just for clarification when you run the AC the air blows a lot of air, but in heat the amount reduces?

Is there a difference between different positions you select (vent, defrost, floor)?

Sorry for the questions just trying to root cause the problem.

 

Trace the air vent tubes from the vents back to the heater core, something might be disconnected. Check the air piping from the fan through the heater core to the vents -- something might be disconnected or blocked.

If the air is hot, the heater core is probably fine, there's just gotta be some kind of obstruction or leak in the flow of air across the heater core to the vents somewhere.

 

Thanks for all the help!
Yes, AC blows a normal amount of air, heat does not.
It seems like all the settings (vent, defrost, floor) are low power.
However, the floor vent doesn’t seem to get hot, while the others do.
And yes, with each power setting it roars louder.
I’ll try tracing the air vent tubes!

 

My money is on a bad blend door actuator. Not a lot of money. But more than pocket lint.

 

I'd check the thermostat. It could be stuck in the open position and not allowing the engine to heat up as much as it should. If they get stuck on the open position it doesn't cause many issues, but in the closed position will overheat the engine.

Or if you bought it used it may not even have a thermostat. My granddaughter picked up a 2007 Mazda to drive about a year ago. It was doing the same thing and didn't even have a thermostat. It was giving the previous owner problems, probably stuck closed, and they just removed it.

 

I'll second the blend door being a potential issue, although shitty to get to. One thing I do want to ask if you turn the heat on full blast, and turn the AC compressor on (defrost) does that change the air flow?

Btw you have quite the interesting issue going on, taking a bit to wrap my head around it LOL

 

I’m going blend door like others
(bad servo motor)

to confirm
Put on heat speed 4, then check ac vents/defrost vents (to see were the forced air is escaping)
Also listen to pitch/strength of fan. I’m pretty sure fan will be spinning at #4 speed no matter what vent selection is made


That would confirm blend door servo faulty

 

Update: it seems like the defrost setting has normal blow power, but the other vents do not.
And there still is variable power between 1-4, they’re just all weaker than they should be.
I’ll look into the blend door thing, thanks