No heat, coolant normal, no codes, AC blows

Not sure why your mentioning the ac system with the engine coolant loop as they have nothing to do with each other.

Any coolant issues on this car is not good. Check the water pump belt and the radiator level. See if the pump weep hole is leaking bad by green flecks all over the belt area. Check rad level not the overflow tank.

The fact you have no heat means there is no coolant circulation in the engine so be very afraid here as that may mean the coolant is not circulating and like a nuclear reactor the engine could severely overheat and you would not know that (no temp gauge!) till you see a thermometer icon on the dash and that means sorry too late the aluminum head is warped and engine needs to be replaced.

i would not drive this car till you figure it out. No temp gauge you have no idea whats going on. Good idea to own a Scan gauge in these circumstances.

Good Luck. This issue here has blown many a G2 motor.

 

Are you checking the coolant level at the radiator? Removing the radiator cap to take a look? Don’t look at the coolant reservoir as that doesn’t tell you if the radiator has enough coolant

 

In winter you need to drive at least 25 minutes to be certain the heater core is getting hot coolant... Usually people don't drive far enough to get to this point and their problem is a heating element that's designed to provide heat before the engine warms up. So checking that fuse and that heating element is the next step after confirming the cabin air filter isn't clogged.

Another thing worth looking into is the valve systems for moving hot coolant around. There's a three way valve that fails fairly often. You'll notice it usually working when you hear the heat storage pump running after you turn the car off. Or if its broken it will make weird clicking sound like an old computer's floppy disc drive. The pump has a position sensor that fails and not sure how that interacts with the heater core, but you need to go through the whole system once you've confirmed engine temperature is all the way up via a phone app with OBD2 device.

 

Well, at this point you can't do much to diagnose the heater until the HV battery works (enough) to be able to start and run the engine. As mentioned - be sure the water pump drive belt is ok. I know you said radiator level was ok - just gotta double check because some people look at the overflow tank and don't actually pull the radiator cap to see what's inside.

When the engine can run I would force it on (ready - turn the heater on, or hold the gas pedal down) while monitoring engine coolant temperature (ECT) with your OBD2 device.

Normally temperature should rise slowly (while the engine runs) up to around 180°F then level off for a bit. Eventually it will go up to around 205° or so before the radiator fan turns on. You could indeed have problems with the heater core, but gotta check if the rest of the cooling system is good.

Usually I would (carefully) feel both heater hoses with the engine and heater both on. With good flow both hoses should be quite hot to the touch. I don't recall which ones actually go to the core- need to look at a diagram.

You could have a problem with the temperature air door inside the dash. One way to test is to turn the ignition on ( press the power button 2x without foot on brake - just be aware the 12V battery can run down quickly if you don't have a charger on it) or go ready if possible. Turn the heater on and twist yourself up to get under the left side of the dash.

Up towards the center of the car above the gas pedal are 2 plastic motor servos with linkage bits behind them. The lower one controls the temperature door. Watch it for movement while someone else changes the heater temperature from full cold to full hot.

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That is the correct place to be checking and the level is full. So you can check those boxes on your list.

 

Can you post a recording?

 

Did you run the engine while monitoring Engine Coolant Temperature with your scantool? It's nice to know that there is coolant hot enough to make the heater work.

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There's no failsafe mode the engine stalled because its way overfilled and oil got into the intake and choked the engine. Engine shuts off but usually the hybrid battery will work and allow you to drive for a while.

Be aware that short drive on battery only is very very hard on the hybrid battery. Very high rate of voltage depletion and very high heat. if you have an original hybrid battery don't be surprised if it pays you back for this.

Many times on this site people who have run out of gas drove till that battery died. Then your screwed. Car wont start and that battery will then have to be externally charged. Requires a high voltage charger. There available now but back then a special one had to Japan.

We saw alot of that in the early days when idiots would run till the gas to the last drop to get the most mileage. Stupid is very expensive.

Also It seems that the Jiffy Lube type joints are all using AllData books for cars oil capacity bible. The Alldata is wrong it shows 5 quarts for a G2 engine.

The G2 engine takes 4 quarts with new filter.

When I need a Jiffy Lube oil change I circumvent there nonsense and always bring them 4 quarts in a jug and the factory filter. They all say hey it takes 5 quarts I say that's nice were using 4 today.

 

FWIW, I chased a no heat problem in my car for a couple of weeks last year. It turned out to be the three-way coolant valve, but it took a while before it triggered a code. However, mine was intermittent which may have had something to do with that.

 

I did not. After a couple of weeks of chasing various things, it finally threw a code and I ordered a replacement at that point. I suppose maybe you could check coolant line temps and see if it's cold going to the heater core from the valve? I didn't look into it too closely since before the code I thought it couldn't be the problem, and after the code I knew it was the problem.

 

That is the sound of the coolant control valve "hunting". More information at this post.

Maybe you were thinking of the engine and inverter/transmission coolant circuits being different? The engine coolant circuit is exactly what supplies your cabin heat.

People sometimes get turned around because the (engine) coolant thermos and (engine) coolant control valve are tucked away more on the transmission/inverter side of the engine bay, close to the inverter coolant pump. But the thermos and control valve still belong to the engine circuit and the cabin heat.