No cabin heat at all. Ideas ?

A man shared with me a diagram of the gen 2 prius cooling system because I was confused about a three way coolant valve. I can look for the diagram. It shows exactly how the system works and all the components including what looks and acts like a big coffee thermos in the front driver side of the car. I'm wondering if that valve getting stuck would bypass coolant from making it to the heater core. I'll dig through the threads and see if I can find some more information for you. I think the man who shared all the knowledge was named Brian from TexasHybrids, however I could be wrong. I have a terrible memory because my oxygen saturation is always so low.

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if it blew cold air, at least you can eliminate the fan assembly. on top of the coolant valve ^^^ you have the water pump and belt, thermostat, and heater core.
i agree with dlc82sv, start there.

 

A 3 way coolant valve failure or blockage in our Gen 2 cars would be the most common cause of the condition you are describing, but that usually comes with a Check Engine Light. You aren't seeing anything like that are you? Other than that, I guess you could do the normal troubleshooting that you would do with this condition in a regular car, namely trying to ascertain whether the heater core has become blocked with sludge. If you have never had the coolant changed, having a blockage in your cooling system would be not all that surprising. I would guess that your best course of action would be to perform a cooling system flush and replace the coolant in your car with a fresh couple of gallons of Toyota SLLC. That should be what is in your car currently if it has never been changed.

 

OP says "all of a sudden." Meaning yesterday had cabin heat, and today no cabin heat?

OP needs to rule out:
3 way-coolant control valve, heater core pump, radiator coolant level.

A defective 3-way collant control valve would have a logged DTC, even if the check engine light is off. Check for codes with a Prius capable code reader (ie, mini VCI w/ Tech stream from Amazon); all other code readers are likely unable to read ALL Prius codes.

The pump for the heater core might have died? But haven't seen issues with that pump. None the less, it is a part that could fail and be a cause of the problem.

OP should check the radiator to make sure there is coolant.

 

Check the coolant level before much of anything else, and check it, like, right now. Don't just look at the plastic reservoir; take off (with the engine cold) the radiator cap and check there.

The last time somebody described those symptoms to me, it took a gallon and a half.

If it takes any, then finding where it went can be the next project. But get coolant in there first.

-Chap

 

Good Morning to all. Hoping someone can help me with this. I drained and refilled my inverter coolant but now no hot air blows in cabin. Toyota told me I need new water valve replaced (16670-21010) which is ordered........but.....the hot air was blowing after Toyota diagnosed this and before I changed coolant!! Would this have something to do with the drain, refill process??? I’m confused and frustrated. Thanks in advance

 

The inverter coolant loop has nothing to do with the heat in the cabin.
If the valve is bad, that is in the engine loop circuit.

Might be time to find another shop or dealer.

 

The inverter cooling system is separate from the ICE cooling system. There has to be a reason your heater stopped working that should have nothing to do with the fact you changed your inverter coolant. How long after Toyota diagnosed the need for a new valve did you lose heat? I believe it may have only be on the verge of failing when they made the diagnosis, and now it has completely failed, thus no heat.

 

are u sure you didn't change the engine coolant?

 

+1

My $ is on you draining the engine cooling loop.

The inverter loop has only one drain spot: left side (USA, N. America, driver side) of the transaxle.

What did you open to drain your version of the "Inverter" loop? Tell us what the object looks like, color, and approximate location in the engine compartment.

 

About a week when diagnosed so you are probably correct. It hadn’t failed YET. I didn’t think it was something pertaining to the flush and fill but needed to make sure. Thanks for the quick reply.
One more thing if you don’t mind? The part I that needs replaced, is that “part” of the water pump or the “water pump” itself? 16670-21010

 

It was the inverter coolant I drained. 24mm socket, solid hex looking bolt and the only drain.

 

It is a separate component in the ICE cooling system. Its main function is control the flow of coolant between the Coolant Heat Storage Tank (the so-called "Thermos") and the rest of the cooling system. The warm coolant in the thermos can be directed back into the ICE's coolant passages on startup to allow for a quicker warmup and less fuel wasted. This video explains the procedure for changing it:

 

Great. You did indeed drain the Inverter loop.

As for no cabin heat and the dealer telling you to replace the 3-way coolant control valve, was there no CEL (Check Engine Light)?
A malfunctioning 3-way coolant control valve will cause that light to stay on, until the valve gets to the right position, then the CEL will turn off. Some people report hearing a rhythmic sound, which is the valve trying to get into the correct position; some report never hearing that sound. No matter what, codes will have been logged if the valve is not in the right position at any time period.

Did the dealer not report P1121? This code is associated with a malfunctioning 3-way coolant control valve.

The upside, this valve won't be the cause of you getting stranded, and it seems to last a really long time. It will be the cause of you being COLD, as you noticed (lack of cabin heat), and it will prevent you from passing your State's Emission Test. This replacement will probably last the life of the car, and it is relatively cheap; $78.47 at Camelback Toyota in Phoenix, AZ.
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