"Auxillary Heater"?

[Analogeezer]

So I joined TDI club way back in 2013 to research before I bought my 2013 JSW.

I seem to recall some discussions about there being an "auxiliary electric heater" that came on first and would shut off when the engine came up to temperature.

Something about to engage this you rotated the heat temp knob from full off to full on.

I cannot find anything in the owner's manual about this.

Was this just some urban legend thing? Actually a thing but on pre-CR TDI's?

I remember at the time thinking this was pretty cool but now I wonder if it was just an urban legend posted here.

Analogeezer

 

[DrGERTol]

Good question -- the aux heater definitely exists according to ETKA; see item 17 here: https://volkswagen.7zap.com/en/usa/golf+variant+sportwagen/gov/2013-685/8/820-820020/#17

 

[DivineChaos]

It's in the HVAC box. It's an auxiliary electric air heater. Heat has to be on full. And it's on when on any fan speed. The older ones had a coolant heater.

 

[DrGERTol]

That's interesting. The wiring diagram tells us that the electric auxiliary heater is option PR-7E6 (not listed on our '11 vehicle information sticker). The wiring diagram also shows connections at Fuse Panel A (front of engine compartment fuse/relay box) at positions SA4 (larger wire) and SA6 (smaller wire), which our '11 has. The wiring diagram also shows relays J359 & J360 in positions 3 & 5 in the relay carrier behind the lower dash panel below the steering wheel (I think our '11 has relays in these positions). It appears that the aux heating element Z35 is controlled by the ECM J623, with input from the "Heater control module J162", but I can't find any other reference to J162 in the wiring diagrams. Hmmm. Makes sense that a North American TDI should have this "option" without it needing to be optional... --g

 

[oilhammer]

It takes a few seconds to look down under the dash to see the big wires going to the heating element next to the heater core.

 

[Analogeezer]

It takes a few seconds to look down under the dash to see the big wires going to the heating element next to the heater core.

I just took a peek and didn't see any wires under the dash, would this be on the driver's or Pax side?

Analogeezer

 

[oilhammer]

Driver side, right next to the heater core. You may have to take the trim panel loose to "see" everything, but the wires are right next to it.

 

[DrGERTol]

And a view of the relay carrier on the left side (before I removed the lower dash panel to add a couple switch circuits to Fuse Panel C last May); note the larger red wires on the right side of the carrier frame (blue and red relay connectors):

 

[Analogeezer]

Thanks guys, so the way you engage this is to set the heat control to full hot? Do you need to have the fan on as well?

I've been doing this since I bought the car and it "seems" to work but I thought it might just be power of suggestion.

My understanding is the aux heat does not get really hot, just takes a bit of the chill off until the regular heat kicks when the engine is hot enough.

Like a lot of the East, our temps have been crazy low this Winter!

Analogeezer

 

[ksing44]

Mine seems to work best with lower fan speeds, e.g., 1 or 2. The heater is likely working just fine at higher fan speeds, but the breeze from more forcefully blowing air makes it feel even colder to me.

 

[Matt927]

There are multiple criteria for this to work including outside ambient temp, fan speed above 2, heat set to max as well as a coolant temperature below a certain value.

 

[TurboABA]

I think as far back as MK5, the PTC details were

Activation conditions
The electrical auxiliary air heater is activated:
- in the case of the 2C-Climatronic and Climatic: automatically via the CAN data bus;
- in the case of the heating system: if the occupants set the heating output to over 90% at the operating unit (analog signal),
- if the water temperature is below 75°C,
- if the engine speed is higher than 500 rpm,
- if no load management system is active and
- if the ECON button is not pressed.

Depending on your HVAC, there might be slight variations to those values, but nothing significant.

One of the test conditions I've seen for the newer models is

Test Conditions
• The intake temperature is below 19 °C (66.2 °F).
• The coolant temperature is below 80 °C (176 °F).
• The passenger compartment temperature is approximately 20°C (68 °F).
• Battery voltage greater than 11 V
• Alternator load not greater than 50 % (terminal DF)
• Engine speed higher than 450 RPM
• Turn the interior temperature knob to maximum heating.

However, keep in mind that the test conditions are only to measure current draw at the small/medium/high outputs of the PTC element and do no really qualify as operational pre-requisites.

 

[taleAwaggin]

So basically keep the temp knob a couple clicks back from max if you don't want it on. That 11v setting seems a little low.. like a volt and a half low.

 

[TurboABA]

So basically keep the temp knob a couple clicks back from max if you don't want it on. That 11v setting seems a little low.. like a volt and a half low.

Not sure I understand what you're saying..... if you don't want it on, it probably means that you don't want heat.... the voltage is a minimum, because you typically already have a low battery at cold startup, and since you're most likely idling and have a bunch of other power consumers on, it can't allow the 1000w heater to put too much of a load on the system. (so it either reduces it's output or turns it off completely to allow sufficient juice for battery charging and all other consumers like lights, etc.)

 

[taleAwaggin]

Thought it'd make more sense if it were set so it cannot run at less than 12 or 12.5 bat volts.

And I like my car heat from non electric sources. VW's seem to have more issues when you ask for lots of watts from them. https://www.google.com/search?q=melt+fuse++jetta

 

[MrCypherr]

Never had an issue with mine. 2013 with 209k km.

 

[taleAwaggin]

Mine has under 100k and melted my fuse box.

I'm not saying keeping your electrical load lower will improve your odds. But one buys a cheap old car that gets 40mpg to save money, one may want to not use the seat heaters. And one may want to keep the heater knob one click back from max. If one is a gambling man. No problems for a year until the winter cold hit and I started using max heat from start up and seat heaters.

Causation versus correlation yeah yeah I know about that too. All I can do is live my data points and report on those.