Supplementary heater & how it works?

makattack · Jan 19, 2016

Ok, I can't seem to get definitive answers when searching. I see references to Mk7's having an automatic supplementary heating system for the passenger climate controls where if the A/C is on, that turns on the supplemental heating system before the motor/coolant is fully warmed up.

Anyone know what type of system it is? Is it all electrical? Does it burn fuel for the heat? Is it a heat exchanger setup tied in with the exhaust system?

I see references to Mk7's having a system that uses a heat exchanger in the exhaust system to provide this supplementary heat, and I also see people talking about how it burns diesel fuel to generate the heat, and I also see people say it's simply an electrical heater (think space heater) that is in-line with the normal coolant/heat exchanger system.

I ask because with my Mk7 G-TDI-SW, I smell a bit more exhaust when I turn on the heater with a cool engine, even when underway. It's not strong, but it seems to go away as the motor warms up.

Matt927 · Jan 19, 2016

You smell diesel exhaust fumes? Probably a small leak at the VNT actuator on the turbo that corrects itself when warm.

Any supplemental heat will be electric.

shepner · Jan 19, 2016

Anyone know what type of system it is?

Somewhere I read that it is an electric heater but I havnt really dug into it to determine wattage and under what conditions that car will enable it. It does seems to make a (slight) difference in how quickly the windshield defrosts.

On a related note, I found out that the mirror heaters wont turn on unless it is cold enough

stephen

TurnOne · Jan 20, 2016

Electricity isn't free. It has to burn diesel to make the electricity for the supplemental heater. I think it has one if you crank the heat up to maximum on my SEL.
But I don't. I wait until it's warmed up to minimize engine heat up time.

Matt927 · Jan 20, 2016

On my Mk6 if I turn the heat all the way to its maximum position and then place the fan setting on 2 or higher the electric element will operate. It operates till coolant temperature is above a certain threshold. I believe there is other operating criteria as well, such system voltage.

I don't see why they would remove it on the Mk7.

Shife · Jan 20, 2016

Matt927 said:
On my Mk6 if I turn the heat all the way to its maximum position and then place the fan setting on 2 or higher the electric element will operate. It operates till coolant temperature is above a certain threshold. I believe there is other operating criteria as well, such system voltage.

I don't see why they would remove it on the Mk7.

The MK7 did not retain the electric aux heater. They moved to a revised cooling system which employs three independently controlled cooling circuits - The "micro" circuit is basically the cylinder head and is intended to quickly provide heat. The rest of the block is on another circuit. The third independent circuit is the water side of the intercooler. All call for water from the same reservoir when needed, but are independent of each other. That 70+ page PDF that floats around regarding the EA288 modular design explains it in detail.

makattack · Jan 20, 2016

Thank you Shife! I found the PDF you mentioned, and downloaded it as it's great! That explains it for me. Thanks also for mentioning the micro circuit, which allowed me to quickly find the correct page for the details. All good to know. This new supplemental heating system based on the micro-circuit cooling stage seems like a nice, efficient design that allows for quicker heating of both the engine and passenger area, although it's clear to me that it would heat the engine up more quickly if heat wasn't removed for passenger comfort. I guess that all depends on vehicle speed/engine load as well, since there's a threshold/point (parameters not stated) where the coolant pump is turned back on.

Back to more reading.

Matt927 · Jan 20, 2016

Are you positive it was not removed? I am reading it is still in European Mk7 2.0 TDI cars.

JCrouton · Jan 20, 2016

makattack said:
Thank you Shife! I found the PDF you mentioned, and downloaded it as it's great! That explains it for me. Thanks also for mentioning the micro circuit, which allowed me to quickly find the correct page for the details. All good to know. This new supplemental heating system based on the micro-circuit cooling stage seems like a nice, efficient design that allows for quicker heating of both the engine and passenger area, although it's clear to me that it would heat the engine up more quickly if heat wasn't removed for passenger comfort. I guess that all depends on vehicle speed/engine load as well, since there's a threshold/point (parameters not stated) where the coolant pump is turned back on.
Back to more reading.

Would you mind linking the PDF on here. I would love to read this also.
Thanks
Marc

makattack · Jan 20, 2016

JCrouton said:
Would you mind linking the PDF on here. I would love to read this also.
Thanks
Marc

Sure thing... just FYI in case you need to find it again in the future, it was the first link when I searched "ea288 pdf" which was this post:

http://forums.tdiclub.com/showpost.php?p=4979589&postcount=9

And this is the direct link to the doc:

http://pics3.tdiclub.com/data/517/820433_EA288.pdf

Matt927 said:
Are you positive it was not removed? I am reading it is still in European Mk7 2.0 TDI cars.

This is what's in the North America (BIN 5 emissions standards) EA288 motor:

Coolant Circuits
The coolant circuit consists of three partial coolant circuits to ensure heat distribution is based on demand.
* Micro-Circuit
* High-Temperature Circuit
* Low-Temperature Circuit

Micro-Circuit
If the engine is cold, the thermal management starts with the micro-circuit, allowing for fast heating of the engine and the passenger compartment. During this fast heating of the coolant, the coolant thermostat remains closed to the radiator.

The circulation of the coolant in the large circuit is prevented by the modulating piston of the switchable coolant pump being pushed over the pump impeller. The resultant “static coolant” heats quickly ensuring that the engine does too.

The coolant in the micro-circuit is moved by the V488 Heater Support Pump. This pump is actuated by the ECM as needed, depending on the coolant temperature in the cylinder head.

The requested passenger compartment temperature is provided by the Climatronic control module and is taken into account when actuating V488.

JCrouton · Jan 20, 2016

Thanks a bunch!! Looks like a good read!

Shife · Jan 20, 2016

Matt927 said:
Are you positive it was not removed? I am reading it is still in European Mk7 2.0 TDI cars.

I can't find anything that supports it being in the car. And thank God for heated seats, because I don't get heat until I'm several miles down the road and even then it is not exactly a furnace. It's not bad, but it definitely isn't instant as if there was an electric element in there. It only is really noticeable in single digit temps. Over 20*F it warms up quickly and produces lots of heat. Below that seems to be when it's most apparent that the car takes a while to produce heat. This depends on my commute as well. In the morning I'm driving with little stoppage from traffic and it heats up quicker. On the way home there is often lots of gridlock and it can take quite a while to get warm.

Matt927 · Jan 20, 2016

I understand the new cooling system but I found this today from another site, possibly dealing with European cars.

"A 1kW electrical auxiliary air heater is installed in diesel vehicles. The electrical auxiliary air heater is a combination of a PTC heater element with an integrated control unit. It is installed downstream of the heat exchanger and provides additional heating of the vehicle interior after cold-starting the engine. The electrical auxiliary air heater directly heats the air which enters the vehicle interior.

Activation conditions: The electrical auxiliary air heater is activated:
• in the case of the Climatronic and Climatic systems, automatically via the CAN data bus.
• if the occupants set the heating output to over 90 per cent at the operating unit.
• if the water temperature is below 75 degrees Celsius.
• if the engine speed is higher than 500rpm.
• if no load management system is active.
• if the ‘Econ’ button is not pressed.”

Shife · Jan 20, 2016

Matt927 said:
I understand the new cooling system but I found this today from another site, possibly dealing with European cars.

"A 1kW electrical auxiliary air heater is installed in diesel vehicles. The electrical auxiliary air heater is a combination of a PTC heater element with an integrated control unit. It is installed downstream of the heat exchanger and provides additional heating of the vehicle interior after cold-starting the engine. The electrical auxiliary air heater directly heats the air which enters the vehicle interior.

Activation conditions: The electrical auxiliary air heater is activated:
• in the case of the Climatronic and Climatic systems, automatically via the CAN data bus.
• if the occupants set the heating output to over 90 per cent at the operating unit.
• if the water temperature is below 75 degrees Celsius.
• if the engine speed is higher than 500rpm.
• if no load management system is active.
• if the ‘Econ’ button is not pressed.”

I'll play with it on the way home. I've never noted any heat until I get about 4-5 miles down the road.

adjat84th · Jan 20, 2016

I'm positive I got luke warm air within a minute of startup yesterday. Heat set on high, fan on 1, 15F outside. I started the car and quickly scraped ice off the windshield and when I got back in the car there was some heat coming out. I don't know if that was the effect of the "micro-circuit" or not, but it was nice either way. I also don't usually request heat from the car until it the needle begins to move. If the aux heater is there, it should be at the footwell and easy to spot right next to the heater core with some thick gauge wiring going to it!

Shife · Jan 20, 2016

As a test I cranked the fan to setting 4 and kept a hand near the dash vent. Outdoor temp on the way home tonight was 20*f. I had lukewarm air after approximately 1 mile. By mile 2 I had pleasantly warm air. At this point the coolant gauge had not moved yet. It took until mile 5 or 6 before real heat started coming on and my coolant temp was about 150*f. I normally don't turn the fan above setting 1 until the temp gauge starts to move, so this was a pleasant surprise.

I have no idea if there is a aux electric heater still. I'll pull the covers off the fuse panels when I have a chance as there should be a sizeable fuse or some sort of electrical protection device for a 1000 watt 12 volt heater.

nikdfish · Jan 20, 2016

Our sel tdi definately has an auxiliary heat unit. Simplest way to get it active is crank the temp knob to "HI" and have the fan above 1. Warm air starts immediately before any coolant has a chance to warm at all. Heat is enough to thaw ice layer off the windshield in short order.

Nick

Bueller · Jan 20, 2016

I have the SEL as well. Any time I turn on the climate control (on auto) and it is around 40 or below the idle will kick up to just over 1000 rpm (to compensate for the increased electrical load) and I'll have heat within 2 minutes of starting the car. If the temperature is in the higher 40's or above the idle does not kick up and it takes longer for heat. I am convinced it has a supplemental electric heater.

RacerTodd · Jan 20, 2016

ETKA does show a "heater element for electrical auxiliary air heater" (how's that for a mouthful!) in the air distribution box, sits next to the heater core.

If your build sheet shows option "7E6" then the electric heater is installed.

Matt927 · Jan 21, 2016

Looking back at the instructions I found, I do not have an "ECON" button on my HVAC controls.

I have always just assumed I have had one on my '15, I will pay more attention this morning when I start the car.

makattack · Jan 21, 2016

Great idea to look for a large fuse. I have noticed on cold starts with the fan on with heat that my motor will idle at about 1000 as well. This is with the ac light off.

Shife · Jan 21, 2016

It should be approximately 100A. It was 12*f this morning and it was about 2 miles before I started to feel any change in temp from the vents. I'm not complaining, but I'm puzzled at the delay since an electric heater should be near instant in temp change. even if the cold plumbing significantly absorbs any heat energy for a while I'm surprised the delay is that long for an electric element.

If I remember I should grab my Fluke and run a temp probe down the vent. That would probably do a better job at detecting a change than my frozen hand.

Matt927 · Jan 21, 2016

Took me about a mile today to get warm air from the vents. 24F OAT.

Matt927 · Jan 22, 2016

Just checked my build sheet. March 2015 build, no electric element in my car per the build sheet.

7E0: W/o heat accumulator/auxiliary heating

Also of note, 9M0: Without auxiliary/parking heater

acrossthepond · Jan 22, 2016

Matt927 said:
Are you positive it was not removed? I am reading it is still in European Mk7 2.0 TDI cars.

You're right its fitted here.

It definitely helps with quicker cabin warm ups.

Can confirm raceTodd's EKTA build code 7E6 ( electric auxiliary air heater) shown on my build sheet.

petee_c · Feb 13, 2019

google brought me to this thread...

Anyone try adding the VW electrical aux heater to their 2015 Golf TDI and activating it with VCDS? My car doesn't have it or the ECON button as far as I can tell, only had it for 3 days though...

JM Popaleetus · Feb 14, 2019

petee_c said:
google brought me to this thread...

Anyone try adding the VW electrical aux heater to their 2015 Golf TDI and activating it with VCDS? My car doesn't have it or the ECON button as far as I can tell, only had it for 3 days though...

If anyone wants to look into adding the auxiliary heater, the part number is 5Q0963235C.

Looks to be about $50-$100 used and $200 new. You’ll need to buy or make a wiring harness and use a VCDS.

It’s only three connections: Positive, ground, and CAN. The hardest part of the install seems to be getting through the firewall to the bus bar.

You can confirm if your car has it (option 7E6) from the factory by running your VIN here: https://carinfo.kiev.ua/cars/vin/volkswagen

Someone added it to their MkV here: https://www.golfmkv.com/forums/showthread.php?t=113468

Supplementary heater & how it works?

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