It’s freezing outside and I have no heat!!

Air bubble holding coolant flow so water no move no heat if water being consumed whilst operating you have heat till water below pumping level very common for this model very costly . Start looking .

 

Take rad cap of degas bottle the reservoir fill it about half way up cap off engine running as it heats water should rise in the bottle. You h elec water pump to make sure it's on .it may start to make heat w cap off half full . If it does put cap on to first detent ride around heat coming??? If so keep riding wen heat stops or cools pull on driveway stop car let it cool a bit . If the heat stopped while you were driving previously then when the car cools a little bit you should see the reservoir quite low if not empty and only down in the hoses or some scenario like that so the system breaks prime and it can't pump the coolant you will have no heat no matter how hot the cooling is getting it won't circulate and go up in the heater core or something to that effect The system has to be full for the water and the pump to move said water or coolant electric pumps do a little better at this but still once they fall down below the reservoir and all that then it's harder for it to pump around an air bubble ensues it's getting stuck around the sensor and throughout the cooling loop and just doesn't produce good flow and that in turn leads you with no heat now you got to figure out where the coolant's going If it's not an obvious hose dripping on plastic or the ground in this model is probably the head gasket very costly very much thought needs to be given to this because many other problems are fixing to arise on this 12 to 15-year-old car or whatever it is now this is not the one.

 

How many miles on the car?

My guess is the engine water pump is not working properly.

Has the coolant high temperature warning light shown on the dash for even a few seconds while driving?

One way to diagnose is to buy an OBD2 Bluetooth dongle and install an app on your phone to monitor the engine coolant temperature. Another way to diagnose is to use a good quality scan tool that is able to look at live data of the pump to compare the requested water pump speed versus the actual water pump speed.

 

The heat from gjt engine is pulled into the cabin. If the i c e isn’t up to temp, you get cold air. That’s what we get for running on the hv battery to save gas.

 

It would be super helpful to plug that OBD-II scan tool back in and use it to watch the coolant temperature while warming up (or trying to warm up!) the engine.

 

Open The jug Make sure it's about half full Don't care about any of the lines turn the car on when you put the heat on high temperature medium fan does the engine immediately come on? It should and it should run until heat comes out of the vents If it doesn't something's wrong like an air bubble in the system that's just moving around it's get stuck in front of your temperature sender turns the light on for a second to a few seconds then the bubble moves and the light goes off and on and on and on check it out but in your car you have an electric pump that may be chunking out because of the plastic coming off the impeller and it's dragging in its bore. But still water should heat up right where the thermostat is and the water pump is and then the thermostat should open pretty quickly without a pump happening I would think and then everything will just stop so both sides of the thermostat housing the water pump and just right where the thermostat is will get hot then you kind of know the thermostat's open or you can pull it out and have a look and make it open in the pot of boiling water in a thermometer usually this is not the problem the thermostat that is I would be looking for the water pump to be acting up in this particular model these also aren't that hard to feel and all that as the previous model I never had any trouble with the generation 2 cooling system or heat didn't have the car running long enough they all blew up but when they were running heat was never an issue as long as the water pump was capable and the cooling system was predominantly sealed as in no leaks never a problem blazing heat quickly too even in minus degree weather.

 

+1 ^ That or put your bare hands, feel the upper and lower radiator hoses. The lower should warm up. The upper will stay cool until the thermostat opens up; but you should feel or sense coolant movement within the hose.

Hope this helps....

 

The brightly illuminated hose at centre of pic is my go-to, say for checking how the block heater's doing:

 

How many miles on her?

 

That's the funny thing even on my broken down generation threes outside the persona will still start and rattle away but boy it'll have heat when it's dark and 16° out in I don't know 6 minutes or something like that no problem as long as that water pump can circulate the water and the system is air free and not leaking sucking air coolant will move and heat will be made and the engine should stay running until the heat is coming out of the vent enough to satisfy the car before the engine will even shut off at least that's how it's been working and all of my cars that I have here and like I say the broken down Persona and even the 2010 loaded solar roof car for put a 12 volt in they'll start right up and have heat within 6 minutes coming out of the vents and if I let it continue to run it'll get blazing hot where you have to turn it down No problem so if your engine's running no problem You need to make sure your coolant is full and no air and then make sure the water pump is in fact moving water which it sounds like in this case it's a prime candidate for maybe not so much or you have air in the system from when the jug went down usually the jug goes down if it doesn't go to air you're good with the air so maybe your pump is actually starting to mess up.