No heat - no sign of heater power

[imstriker]

We got down below 0 last night and it looks like my heater might have bit it. Car was plugged in last night, preconditioned on set time but was ice cold.

It's not blowing any warmth and the heater pipe by the brake reservoir is ice cold. Car scanner seems to show no sign of life. I'm sure it will be a dealer call, but anything I'm missing?

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[Mach-Lee]

So the car is fully turned on (not remote started) and you have the HVAC on set to AUTO? And you’re not seeing any coolant heater power? Yeah heater may have died or a high voltage fuse blew.

 

[imstriker]

So the car is fully turned on (not remote started) and you have the HVAC on set to AUTO? And you’re not seeing any coolant heater power? Yeah heater may have died or a high voltage fuse blew.

Yes, let it sit out there fully turned on for about 30 minutes, never saw any heater power. Drove it earlier and didn't get any heat either.

Hadn't thought of fuse. Is that something I can check? Not seeing it on the normal diagrams.

 

[Mach-Lee]

Yes, let it sit out there fully turned on for about 30 minutes, never saw any heater power. Drove it earlier and didn't get any heat either.

Hadn't thought of fuse. Is that something I can check? Not seeing it on the normal diagrams.

I think it's going to be dealer time for you then. The fuse is inside the HVBJB in the battery pack, not something you can access.

 

[imstriker]

I think it's going to be dealer time for you then. The fuse is inside the HVBJB in the battery pack, not something you can access.

Makes sense. Making that call tomorrow. Appreciate the reply from the forum heating guru

 

[pr0t0c0l_dr01d]

Might be a red herring but this exact symptom happened to my car the day before the hvbjb threw a stuck contactor message in my car. I had no heat on my commute in spite of having set a departure time. The next day the heat was working again, but the car died before my afternoon commute.

 

[Shayne]

When it got really cold and I had no heat it was most of the times the coolant was frozen in the hoses. Squeezing working the heat up the hose loosened it up and then heat. Wonder when it warms up if you will have heat again (in the shop)? If so make sure they check the coolant.

 

[pr0t0c0l_dr01d]

When it got really cold and I had no heat it was most of the times the coolant was frozen in the hoses. Squeezing working the heat up the hose loosened it up and then heat. Wonder when it warms up if you will have heat again (in the shop)? If so make sure they check the coolant.

That’s very interesting. I wonder if a failure of coolant flow is what led to my hvbjb failure.

 

[Mach-Lee]

When it got really cold and I had no heat it was most of the times the coolant was frozen in the hoses. Squeezing working the heat up the hose loosened it up and then heat. Wonder when it warms up if you will have heat again (in the shop)? If so make sure they check the coolant.

He's in Indianapolis, I don't think it's cold enough there to freeze factory coolant like northern Canada. It's about 10ºF/-12ºC there. Factory 50% coolant shouldn't freeze until about -35º or so.

That’s very interesting. I wonder if a failure of coolant flow is what led to my hvbjb failure.

No, HVBJB failure has nothing to do with coolant. If the contactors were sticking, then you might lose power to the heater, but a code should be set for that.

 

[Shayne]

He's in Indianapolis, I don't think it's cold enough there to freeze factory coolant like northern Canada. It's about 10ºF/-12ºC there. Factory 50% coolant shouldn't freeze until about -35º or so.

It is always the small heater hoses that will go slushy (plug). Have no idea the mix of the coolant in his vehicle.

 

[pr0t0c0l_dr01d]

He's in Indianapolis, I don't think it's cold enough there to freeze factory coolant like northern Canada. It's about 10ºF/-12ºC there. Factory 50% coolant shouldn't freeze until about -35º or so.



No, HVBJB failure has nothing to do with coolant. If the contactors were sticking, then you might lose power to the heater, but a code should be set for that.

I certainly got no message on the dash while my heat wasn’t working.

 

[Mach1E]

I think it's going to be dealer time for you then. The fuse is inside the HVBJB in the battery pack, not something you can access.

Seriously?

That seems like a horrible place to put a fuse.

Gotta drop the whole battery pack to get to a simple fuse?

If that’s where they put it, they should at least have the car throw a code when it pops.

 

[pr0t0c0l_dr01d]

Seriously?

That seems like a horrible place to put a fuse.

Gotta drop the whole battery pack to get to a simple fuse?

If that’s where they put it, they should at least have the car throw a code when it pops.

I’ve been thinking about this a lot lately. I would love to understand Ford’s engineers’ reasons for putting these fuses and contactors in such an inaccessible place. Is it purely for safety to prevent shocks? To keep them isolated from water intrusion with the rest of the battery? As the traffic cop for all of the vehicle’s power, the hvbjb is really the heart of the car.

Dropping the whole battery pack to fix it or maintain it is such a whopper of a job. Feels to me like it belongs in a more maintainable place.

 

[Nolanbro]

I’ve been thinking about this a lot lately. I would love to understand Ford’s engineers’ reasons for putting these fuses and contactors in such an inaccessible place. Is it purely for safety to prevent shocks? To keep them isolated from water intrusion with the rest of the battery? As the traffic cop for all of the vehicle’s power, the hvbjb is really the heart of the car.

Dropping the whole battery pack to fix it or maintain it is such a whopper of a job. Feels to me like it belongs in a more maintainable place.

My guess is since the heater is high voltage, they keep all that together so regular people don't mess with it, as well as packaging

 

[Mach-Lee]

Seriously?

That seems like a horrible place to put a fuse.

Gotta drop the whole battery pack to get to a simple fuse?

If that’s where they put it, they should at least have the car throw a code when it pops.

I’ve been thinking about this a lot lately. I would love to understand Ford’s engineers’ reasons for putting these fuses and contactors in such an inaccessible place. Is it purely for safety to prevent shocks? To keep them isolated from water intrusion with the rest of the battery? As the traffic cop for all of the vehicle’s power, the hvbjb is really the heart of the car.

Dropping the whole battery pack to fix it or maintain it is such a whopper of a job. Feels to me like it belongs in a more maintainable place.

For safety, fuses need to be as close to the source of power as possible since they cannot protect upstream. As a result, high-voltage fuses are almost always inside the battery pack on EVs. It also needs to be inaccessible to anyone who thinks they can just swap a high-voltage fuse without any training. That is seriously dangerous compared to changing a 12V fuse. Regular people should not be touching high-voltage fuses, just like you shouldn't be working on your power line. They have it in the proper place inside the battery pack.

There may be a code; not all codes or errors are shown on the screen. The dealer can diagnose. The fuse blew for a reason, you don't just change the fuse until you figure out the cause. Since I haven't looked at it, the fuse may be okay and it could be just the heater that is bad.

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