Heater in 2020 Tacoma Only works intermittently

Hello All,
I have a 2020 Tacoma with a V6. Last month the heater suddenly stopped working. The engine doesn't seem to overheat though and doesn't take exceptionally long to heat up, though, which is confusing.

I checked coolant levels and all was good. I checked the two hoses that feed the heater core, both were the same temp. I took the car into firestone, they checked it out and looked at the levels, and said that nothing was wrong with it. They refused to charge me since they said the coolant still had some life in it and the cooling system is basically fine.

A week after taking it into firestone, the heat suddenly started working again, easily heating the cab to the point of sweating and then having to turn it off. Now, three weeks later, the heater is not working again. I can't for the life of me figure out what's wrong with it and I really don't want to take it into the dealer because they're going to charge me an arm and a leg and it will likely take a day or two out of my schedule.

THe truck has 105,000 miles on it.

Does anybody have any clue as to what could be going on here? Could it be a software issue? Could it be a heater control valve? Is there anyway I can at least diagnose this myself so I dont have to deal with the dealership, or is the dealership the only way forward?

Many thanks in advance.

 

My guess would be a stuck thermostat.

 

I think I read where there is no heater control valve on these trucks. I believe there is adoor that swings between hot and cold to regulate the temp. Your actuator may not be working properly.

 

welcome

air movement but no heat, blend door(s)

 

Does the blower work well on all speeds wnen this happens?

 

Yeah the blower works great, it just doesn't blow warm air, but the air is also slightly warmer than the outdoor ambient air temperature so I'm not sure if it's getting heat somewhere, seems like it might.

If the issue is a stuck thermostat, is that an issue that only a dealer can fix? Where I live there are few mechanics I trust in terms of competence, unfortunately. I may as well go to the dealership if only to avoid having to continue returning to a non-dealer mechanic when the issue isn't fully resolved.

Any insight or advice appreciated. Thanks

 

If the thermostat is stuck open, it will take longer than normal for the truck to come up to temp (depending on how cold it is where you are it may be taking longer than usual anyways), If stuck closed the truck would overheat.
Not hard to change the thermostat if you are handy.

Blend door actuators and linkages are on the passenger side of the air box and have been known to get jammed by dogs nosing around under the dash
Should be able to see them if you go in like you are changing the cabin air filter and look to the left, see if them move changing air flow/temp settings

 

Turn the fan speed up to the highest setting and then try each adjustment (face, feet, defrost, ect). You should be able to hear the blend actuator change with each selection.

If it's not the blend actuator I'd guess the heater core has a clog; in which case you should flush the coolant/radiator. When's the last time the coolant was changed or flushed? 105k miles is quite a bit.

edit: A clog or debris in the cooling system could also contribute to the thermostat sticking.

Definitely flush the cooling system if you haven't done so recently.

 

It's only 38 degrees (not exceptionally cold) and yes, the truck is taking ten minutes to heat up to the middle of the dashboard thermostat, which does seems a bit longer than usual. IF the thermostat is stuck up on open, could it have become unstuck and thus caused the cab heater to start working for a few days two weeks ago? THe fact that it briefly started working again is really confusing.

 

Do you have the manual HVAC controls or the digital control panel? Digital system could be something as simple as a sensor, the guys suggesting a blend door are offering good suggestion to check out.

 

Sounds like a system flush is the best place to start. Thermostats don't cost much and can be changed during that time. That's where I would start.

 

I like the flush suggestion first. The heater core should be throwing heat all the time. It is just like your radiator out in front of the motor....but just smaller and inside for your warmth. Really sounds like you have chunks of sludge floating around in there. Also some chunks could be blocking the flow in the motor also causing the slow warm up on the gauge. This is the cheapest and easier way to start

 

When you’re driving around with no heat, what temp is the motor at? You should be getting good warmth when the needle is all the way up, which happens at around 150°-155°. Though temps keep climbing to 195° after that but you can’t see that without monitoring the OBD.

It sounds more like the blend actuator for hot to cold is malfunctioning. Even if it takes 10 minutes to fully warm up (which is definitely slow), you should still be getting substantial heat when it’s warmed up or close to it.

As stated there is no heater control valve so what you measure at the hoses is what you get at the core (unless the core is in poor shape and not dissipating heat right). Very likely the hot to cold actuator is problematic.