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397 Amp Alternators plus Supplemental Heat

Controlsengineer

Tremor Fan
Joined
Aug 11, 2020
Messages
26
Reaction Points
29
Location
Beckley, WV
Current Ride
20 Tremor F350 Velocity Blue
My 20 has this option. How does it work? or what does it do? I would like to think it makes heat electrically when its cold as soon as the engine starts. But last night I drove it and it was around 34 degrees. It seemed to take several minutes to start making heat. about the same time as my F150 ecoboost. Is this normal? Does it take way longer to make heat if you don't have the Supplemental heat option, so therefor it worked and I just thought is was normal?

Also, with the two alternators and batteries, are they solely to be used for the heater, or can I add a big power inverter? Why didn't ford up the specs on the 120 outlet with the big alternator option? that seems appropriate.

CE
 
it's a heating element in the ducting that warms air as it passes over the coils. works well but isn't a furnace. i've got it and love it. dual batteries and upgraded alternators aren't for the heater. they're for potential additional electrical loads like lights, winches, compressors, etc
 
I have the supp heater too and am not very impressed
 
Is it just automatic I assume? I can’t seem to find a separate control. I didn’t look for an indication on the climate display screen tho.

I accidentally found out I had the heated steering wheel when I just happened to hit the Home Screen button and saw the symbol. I didn’t think I had that option. Pleasantly surprised. I love the truck just that much more now
 
it operates automatically. its temperature regulated i believe and comes on based on hvac settings and ambient temp.
 
I checked the manual under the fuse section. It says it has three 50 amp fuses. They’re installed. And not blown. Being able to pull that many amps should make some heat. I started it up and it ran for 5 minutes or so. Never did even start to get warm. It’s 34 outside. I’m not impressed.
 
Use a thermometer in the vents and see what temps are coming up. I’ll do the same when I get a chance and report back. My truck is pretty warm in the morning after a few minutes of run time. I’ll set my temp to high and see
 
it's a heating element in the ducting that warms air as it passes over the coils. works well but isn't a furnace. i've got it and love it. dual batteries and upgraded alternators aren't for the heater. they're for potential additional electrical loads like lights, winches, compressors, etc
The 397A alternator may not be strictly for the supplemental heat but if you add the supplemental heat or the winch as an option it will automatically add the 397A alternator option.
 
Unfortunately my truck doesn’t have supplemental heat.
Does anyone know if it can be added now? Would be nice on the cold Michigan and Montana mornings.
 
it operates automatically. its temperature regulated i believe and comes on based on hvac settings and ambient temp.
I think it comes on just with temp..........at night my truck is always set to max ac cause it is warm every afternoon in NC.....but lately on cold mornings I grab the wheel...and its HOT!!! Love that Feature!!!!
 
The sup heat works is just like a space heater. it heats the air via coils. Now it wont every get "hot" but ive used it enough now to know, it will melt ice off windshields when the motor is cold. It does reduce airflow on heat until the motor gets up to temp. once it does, then the HVAC blasts like the gates of hell. Its not to warm your truck and make it comfortable, its to take the edge off and melt ice.

Thanks
 
when I started it, I had the setting on Auto, and dialed the temp up to High and the fan didn’t even come on. I let it run for a few minutes, still no air blowing in Auto. I goosed the fan button up a couple times, then all the way to max. It came out of Auto, and started blowing COLD air.

It would be nice to know if like it only works in defrost mode, or with recirculating on. Or below 32 degrees. Only when temp is set to High. Or climate control in Auto. Or what.
 
The 397A alternator may not be strictly for the supplemental heat but if you add the supplemental heat or the winch as an option it will automatically add the 397A alternator option.

I agree. When I added the supplemental heater, the ordering system automatically added the 397A alternator. I tried to remove it to verify it was needed, and the ordering system said I had to remove the heater.

My dealer told me it takes 20+ minutes to heat up the diesel cab when you do not have the supplemental heater, so it was a no-brainer for my always-cold wife!
 
I agree. When I added the supplemental heater, the ordering system automatically added the 397A alternator. I tried to remove it to verify it was needed, and the ordering system said I had to remove the heater.

My dealer told me it takes 20+ minutes to heat up the diesel cab when you do not have the supplemental heater, so it was a no-brainer for my always-cold wife!
Good to know. I ticked most of the boxes so not sure what was stand alone or not.
 
I agree. When I added the supplemental heater, the ordering system automatically added the 397A alternator. I tried to remove it to verify it was needed, and the ordering system said I had to remove the heater.

My dealer told me it takes 20+ minutes to heat up the diesel cab when you do not have the supplemental heater, so it was a no-brainer for my always-cold wife!
it takes 3 mins to have heat with the cab heater .... no regrets getting it
 
when I started it, I had the setting on Auto, and dialed the temp up to High and the fan didn’t even come on. I let it run for a few minutes, still no air blowing in Auto. I goosed the fan button up a couple times, then all the way to max. It came out of Auto, and started blowing COLD air.

It would be nice to know if like it only works in defrost mode, or with recirculating on. Or below 32 degrees. Only when temp is set to High. Or climate control in Auto. Or what.

Based on other replies, you might want to have yours checked to verify it is working.
 
Yea what I was thinking. If it does work based on ambient temperature how would they test it. My buddy is Ford dealer mechanic. He said he didn’t know how it was supposed to work. I’m sure he can find out thru the tech line. But he’s also busy I’m sure making actual repairs rather than worrying about my possible non problem. I’m going to make some more cold start trips and note the results.
 
I found this on another forum...it appears the sup heat is a remote start only thing?

Remote start and DATC (Dual Automatic Climate Control)...

For cold ambient air temperatures as determined by the HVAC module AUTO mode to request heat:

-the airflow mode is set to FLOOR/DEFROST.
-the temperature is set to 22°C (72°F).
-the blower speed is set to AUTO.
-the air inlet mode is set to AUTO.
-the auxiliary electric heater is enabled if needed (diesel engines only) (if equipped).

For moderate ambient air temperatures as determined by the HVAC module AUTO mode to request heat or cooling:

-the airflow mode is set to the AUTO.
-the temperature is set to the last user setting (Temperature setting is limited to 18°C (65°F) minimum and 29°C (85°F) maximum. If the temperature is set above or below that range, it will use the minimum or maximum value.).
-the blower speed is set to the AUTO.
-the air inlet mode is set to AUTO.
-the auxiliary electric heater is enabled if needed (diesel engines only) (if equipped).

For warm ambient air temperatures as determined by the HVAC module AUTO mode to request cooling:

-the airflow mode is set to AUTO.
-the temperature is set to 22°C (72°F).
-the blower speed is set to AUTO.
-the air inlet mode is set to AUTO.
-the auxiliary electric heater is not enabled (diesel engines only) (if equipped).
 
I found this on another forum...it appears the sup heat is a remote start only thing?

Remote start and DATC (Dual Automatic Climate Control)...

For cold ambient air temperatures as determined by the HVAC module AUTO mode to request heat:

-the airflow mode is set to FLOOR/DEFROST.
-the temperature is set to 22°C (72°F).
-the blower speed is set to AUTO.
-the air inlet mode is set to AUTO.
-the auxiliary electric heater is enabled if needed (diesel engines only) (if equipped).

For moderate ambient air temperatures as determined by the HVAC module AUTO mode to request heat or cooling:

-the airflow mode is set to the AUTO.
-the temperature is set to the last user setting (Temperature setting is limited to 18°C (65°F) minimum and 29°C (85°F) maximum. If the temperature is set above or below that range, it will use the minimum or maximum value.).
-the blower speed is set to the AUTO.
-the air inlet mode is set to AUTO.
-the auxiliary electric heater is enabled if needed (diesel engines only) (if equipped).

For warm ambient air temperatures as determined by the HVAC module AUTO mode to request cooling:

-the airflow mode is set to AUTO.
-the temperature is set to 22°C (72°F).
-the blower speed is set to AUTO.
-the air inlet mode is set to AUTO.
-the auxiliary electric heater is not enabled (diesel engines only) (if equipped).

I do not have mine yet, or I would try it for myself. Let us know if using the remote start improves the heating of the cab.
 
So I have my remote start HVAC settings for auto based on air temp. I have the seat heat and cool on auto as well. I always leave my HVAC in auto and never change fan speed of vent setting. HVAC gives preference to cowl and floor when it runs initially to help with defrosting. I ran auto start this AM for about 10 min. 34 degrees freedomheit ambient air temp. I didn't use a thermometer to check the cab temp because it was noticeably warmer. seats were warm, cab was warm. check you HVAC settings for auto start and see that they are set to your liking. If it's still an issue check with the service guys to make sure it's working
 
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