Hot air coming out all the time when gas engine is on

you don't say what your hvac settings are

 

temp set to...

 

recirc or fresh air?

Over the winter I use recirc to keep the cold air out,
but I have noticed with fresh air now, the heat from engine is coming in now.

Diff model i know, but outside temps are changing?

 

That's normal! The car will let fresh air pass through the HVAC vents using the last temperature set when you turned off the system. It will warm the outside air based on the temp setting with you turned it off. If you want to turn off the HVAC, first lower the temp all the way down and then you will get fresh air without any added heat. You can also manually select the vent settings with the system off.

 

hmm, does sound a little odd. i do notice the air through the engine compartment can be warmer than outside temp, but how warm is warm?

 

might be worth a 12v reboot

 

Lots of hot-air? Sounds like it's suffering from the "Washington Syndrome".


Posted via the PriusChat mobile app.

 

negative. won't hurt anything, but you can lose radio presets, window function, trip meters, etc.

 

I had the same thing happen on a previous C-Max except it only occurred on the passenger side vents.

Next time it happens (don't turn off), take it straight to a dealer so they can verify for easier warranty process. I had no codes or trouble lights.

 

HVAC controller part of some sort. I assume it was part of the hardware to allow dual (passenger) control. Having the service manager see it happened really helped speed up the repair process.

GOOD LUCK!

 

Hi Thorn, my 2017 Prime has the same heater always on problem. Unfortunately, my Prime is out of warranty so I'm on my own. The dealer asked for $6000 to fix it. They said they need to replace the whole heater box. What was the fix that resolved your Primes problem? Thx!

 

Looking at this picture, pay attention to the little servos (callouts 87050C, D, and E, and 87130K). Those are what move the doors around inside that box. Different doors do different things: select where the air comes in from (fresh or recirculated), select where it goes (feet, face, defrost, ...), and control how hot it gets (by mixing or blending how much air goes through the heater core and how much goes around it). It's that last one that can lead to this kind of symptom, if that door is stuck in one position and the air is always going through the heater core.

People call that one the air mix servo or the blend door servo. (Some people kind of call all the servos "blend door" servos, but of course that's the wrong name for the other ones.)


HEATING & AIR CONDITIONING - COOLER UNIT. 2017 Toyota Prius Prime | Toyota Parts Center Online




Unfortunately, that parts list does not name the different servos clearly enough to tell which one is the air mix servo. I've noticed that before, even with earlier models; between engineering and the parts catalog, somebody always mixes up the names of these servos. This list is calling "air inlet door actuator" the one farthest from the air inlet door, and I really doubt that's right.

The place to see which servo really is which would be in the repair manual or the new car features manual, both described here:

Toyota Service Information and Where To Find It | PriusChat

Although the servos aren't very expensive, there's no getting around that a lot of dash disassembly might be needed to get down there. The dash really is made to come apart, more easily than it looks, but there are a lot of steps and it's tedious, and expensive if billed by the hour. Also, the 'smarts' of the servos really are built into the little wire harness, 82210K, so sometimes that's where the problem is.

Finally, sometimes the case is that the air mix door or its shaft really did break or jam up inside the box. Those parts aren't sold separately, so if that's the issue, Toyota really wouldn't have any fix short of replacing the whole box.