2023 Lightning Lariat - Heater Not Working

[Adventureboy]

I agree, fill it again. I might take a few drive/cool cycles to pull the coolant in and expel the air pockets. If you still have no heat you should call your service department. They should be able to see if the truck is throwing any codes.

There have been cases where the coolant freezes in the pipes to the cabin heater but I don't think you are cold enough for that.

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[grizwizwg]

I'm grateful for the input. Going to let it sit overnight, put enough coolant in tomorrow to get closer to the Max line, and will keep you all posted. I'm gathering heat should clearly come back soon, so won't wait too long on that.

 

[grizwizwg]

Update, I added an additional 1 quart of coolant. The level in the reservoir was near the Max line. Drove around for about 30 minutes, hilly areas, heat (actually cold) on blast, no joy on the heater. Came home, coolant level was about exactly midway between Min and Max. Coolant is definitely working through the system, hopefully pushing out air pockets. Seems to be holding steady there. No signs of leaking underneath the truck, on the pavement, or anywhere I can see underneath with a garage creeper & flashlight.

Going to try again tomorrow. On the plus side, temps are above 50 again

 

[Grumpy2]

Coolant is definitely working through the system

Here is a video that shows what your dealer should have done to remove the air from the system. This video shows the air removal from a Mach-E with two reservoir bottles, but the process is the same for our one reservoir bottle Lightning. Go to the 29 minute portion:

 

[Adventureboy]

I think at this point, it is a dealer call. You've taken the steps to remove the obvious. Let them fix it now.

 

[tearitupsports]

Update, I added an additional 1 quart of coolant. The level in the reservoir was near the Max line. Drove around for about 30 minutes, hilly areas, heat (actually cold) on blast, no joy on the heater. Came home, coolant level was about exactly midway between Min and Max. Coolant is definitely working through the system, hopefully pushing out air pockets. Seems to be holding steady there. No signs of leaking underneath the truck, on the pavement, or anywhere I can see underneath with a garage creeper & flashlight.

Going to try again tomorrow. On the plus side, temps are above 50 again

I ended up having to add about 3.5 quarts total until it finally has a steady level. My heat has now returned to really good levels. That being said mine got progressively better each quart I added, so you may have a secondary issue. When it was bad I could feel my heat cycling on and back off (warm air to cold air and back about every 10-20 seconds).
The good news with mine is that there seem to be no permanent damage issues. I took a 5000 mile road trip being 3 quarts down in the middle of the summer. I started hearing sloshing sounds when at charging stations and should have checked sooner. It wasn't until I researched on my heat cycling issue that this forum pointed me to the answer.

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