Heater cant “keep up”

Your heater cores are most likely plugged. Mine had zero heat a few years ago. Now I can fry eggs on the dash if I want.

Thermostat open is east to diagnose. Does it take more than 5 minutes to get the engine up to a reasonable temp? Is the radiator and overflow full?

Odds are just plugged cores.
 
3bears said:
than mine must not have been working corrrectly, as it would kick on even at minus 20. you could here it kick on and the engine speed up
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So does mine. It's how our defrost system works. All it needs is a few seconds on to defrost faster. That's all it's used for. :)

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Well. Tried the heater core flush with vinegar today. No change. Seems like soon as I get about 45 mph and its decently cold (Tonight was 45) it starts blowing cold. No idea what it could be. The heater valve works, can feel heat on both sides of it. If I'm just sitting there not moving, blows hot. Don't get it.

Got a Scan Gauge 2 for christmas, coolant temps staying around 197-207.
 
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Maybe you have the actuator going goofy on your blend door. Does all the modes seem to function properly when you switch the vents?

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Welp thought I had it. Ended up redoing the flush with CLR and it seemed to have helped, but with it being super cold here now it seems to have come back. Seems like anything under freezing and it has issues keeping up. Getting frustrating lol. Might just put a new heater core in it this summer.

I saw where a guy was able to get to his core and clean out debris but I couldn't figure out how he did it without tearing apart the whole dash, he said he just took the glove box out and that vent tube and presto. I did that and was able to pull that sensor out of the small hole and look in there and it didn't look bad to me.

So far I have:

New coolant.
New thermostat.
Flushed with vinegar, then with CLR (filled with CLR, waited 15 min, flushed)
New actuator/tested old ones work fine. (mine was missing a blend door one when I got it)
No leaking around water pump. (Did timing belt kit < 5000 miles ago)

Not sure what else to try. Want to play in the snow lol but I need to see where I'm going!
 
405Runner said:
Welp thought I had it. Ended up redoing the flush with CLR and it seemed to have helped, but with it being super cold here now it seems to have come back. Seems like anything under freezing and it has issues keeping up. Getting frustrating lol. Might just put a new heater core in it this summer.

I saw where a guy was able to get to his core and clean out debris but I couldn't figure out how he did it without tearing apart the whole dash, he said he just took the glove box out and that vent tube and presto. I did that and was able to pull that sensor out of the small hole and look in there and it didn't look bad to me.

So far I have:

New coolant.
New thermostat.
Flushed with vinegar, then with CLR (filled with CLR, waited 15 min, flushed)
New actuator/tested old ones work fine. (mine was missing a blend door one when I got it)
No leaking around water pump. (Did timing belt kit < 5000 miles ago)

Not sure what else to try. Want to play in the snow lol but I need to see where I'm going!
Click to expand...
Could try bypassing the heater valve to see if that helps.
 
alumarine said:
Could try bypassing the heater valve to see if that helps.
Click to expand...

So I was wondering about that yesterday as well, it has always cycled like it was supposed to but I thought hell it may be messing up so yesterday I went and got a dual 5/8x5/8 connector and jumped it, no change. The inside of the heater valve was wide open as well. It did have a small chunk broke off of the passenger side of the valve maybe 1/8th inch by 1/4 inch. Wondering if that got in there and is causing a blockage. Kind of what led me to thinking I just need a new core since obviously the CLR wont dissolve that and I def don't want it to end up in the engine lol.
 
405Runner said:
So I was wondering about that yesterday as well, it has always cycled like it was supposed to but I thought hell it may be messing up so yesterday I went and got a dual 5/8x5/8 connector and jumped it, no change. The inside of the heater valve was wide open as well. It did have a small chunk broke off of the passenger side of the valve maybe 1/8th inch by 1/4 inch. Wondering if that got in there and is causing a blockage. Kind of what led me to thinking I just need a new core since obviously the CLR wont dissolve that and I def don't want it to end up in the engine lol.
Click to expand...
I'm guessing you don't have a rear heater to see if it's working well?
 
Can you reverse the flow through core and drive it a little and see if it gets better?

When you drain your rad is any sediment in your bucket?


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I find it very curious he gets heat stopped and loses it going 45moh. I think people here may be focusing on the hydraulic part of the equation when the issue may be airflow. Not as a permanent fix, but as a diagnostic, I would suggest trying to block the outside air flow inlet and see what that does. (It's only 9°F here, so I'm not going outside and try to figure out how to do it.) If that restores heat while in motion, you can then stop sweating channels and valves and thermostats, and start worrying about blend doors and linkages.

Just my $0.02.
 
Have you checked your vent temp at idle when the motor is good and hot?
If I drive mine for say an hour at 12 degrees F my center vent temp is 160 F at idle.
 
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