GLS Class (X167) Produced 2020 to present

Almost Instantaneous Heat -- HOW?

Old Nov 13, 2023 | 10:07 PM
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'20 GLS450, '17 S550 Sedan
Almost Instantaneous Heat -- HOW?

Help me understand! How does the GLS produce almost instantaneous heat? I just got back from a trip and our '20 GLS450 was parked at the airport (covered, but not in a garage). The ambient temp was about 30°F, yet by the time I had backed out of my parking spot and driven to the end of my row, I noticed I had cabin heat! The engine had been running less than one minute. The climate control was set to 73°F, using "Auto" and "Sync." The heated seat and heated steering wheel were both on (I doubt that matters, but I'm including all variables).

I've owned 9 previous Mercedes, and the only other one that produced nearly instant heat was our 2007 R320 CDI. I always assumed the CDI had some sort of electric or auxiliary heater to give the cabin quick heat, since diesel engines naturally warm up so slowly.

Does the Mercedes 48V system include some sort of special cabin heating functionality, either directly or indirectly? Can one of you explain how it seems to produce nearly instant heat? I did find a similar question posed in the W213 forum, but I didn't see a satisfactory answer.

Thank you in advance...!
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Old Nov 13, 2023 | 10:14 PM
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2012 E Cabrio, 2015 GL , 2017 B ED & 2024 GLS
Another data point to support - I remote-started the car a couple of weeks ago. The app told me it had 3C inside the car (I guess that's 38F). After 7 minutes, just before I got in the car, it showed me 70 degrees and it was pleasantly warm. Witchcraft. My old GLC would need 2 10 minute cycles and it would still not be THAT warm.
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Old Nov 14, 2023 | 12:07 AM
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GLS 450
I am no expert, but I do read these forums. I saw a post where someone posted their car's service record. One of the items listed was a 'fault in the ELECTRIC supplemental' heater.

So I think the GLS has auxiliary electric heat that comes on first while the engine is still cold.

Others can chime in if I am wrong.
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Old Nov 14, 2023 | 07:42 AM
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@mercedesbuff, can I assume that you did use the Remote Start before getting to your car? How long was the head start?
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Old Nov 14, 2023 | 10:08 AM
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'20 GLS450, '17 S550 Sedan
No remote start ahead of time. When the shuttle dropped me off at my parking space, I unlocked the car, loaded my suitcase, got into the driver's seat, started the engine using the button on the dash, turned on my seat heater and steering wheel heater, plugged in my phone, fastened my seat belt, set navigation for home (not because I don't know how to get home, but because I wanted the live traffic dynamic re-routing), and then backed out of the parking space. By the time I was at the end of the row, I had cabin heat. Engine had been running less than one minute, in my estimation. Maybe 90 seconds...tops.
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Old Nov 14, 2023 | 10:12 AM
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@wyatt88, you are correct. The battery provides instant heat.
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Old Nov 14, 2023 | 10:40 AM
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'20 GLS450, '17 S550 Sedan
After reading @wyatt88's reply, I did a couple of Google searchs for "Mercedes electric heater" and "Mercedes engine pre-heater," and I found several references to this part: A 000 835 73 00... So maybe this is the magical part that gives me almost instantaneous cabin heat!



Whatever it is, I like it!
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Old Nov 14, 2023 | 05:39 PM
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Originally Posted by mercedesbuff
After reading @wyatt88's reply, I did a couple of Google searchs for "Mercedes electric heater" and "Mercedes engine pre-heater," and I found several references to this part: A 000 835 73 00... So maybe this is the magical part that gives me almost instantaneous cabin heat!



Whatever it is, I like it!
Hmmm even the GLE has it? That is the first time I hear about that, interesting discovery OP.
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