What is Auxiliary heater?

[MyDimeIsUp]

Currently sitting in the waiting room at my Audi dealer (Have to be 25 or older to get a loaner car) for after run coolant pump and auxiliary heater recalls. What does the auxiliary heater actually do and how do you control it? I only switched mine off in my MMI since that is what the recall said to do until the recall is performed.

[alhutch]

It provides electric heat for the interior before the engine coolant is up to temp and able to. You don't control it directly, the car's HVAC system does. You can turn it on or off via MMI, as you stated. Make sure you turn it back on after the recall (mine was left off in MMI).

[Theiceman]

Im not i have that or can control it. Do all cars have it ?.

Sent from my SM-G973W using Audizine mobile app

[MyDimeIsUp]

It provides electric heat for the interior before the engine coolant is up to temp and able to. You don't control it directly, the car's HVAC system does. You can turn it on or off via MMI, as you stated. Make sure you turn it back on after the recall (mine was left off in MMI).

Ok thanks. I've read it also cools the car but that seems a little counterintuitive considering the name "auxiliary heater". I've read it also allows me to heat (or cool apparently) without turning the engine on since it has a fuel pumped to the auxiliary heater as well. Is this correct?

Thanks for the current information you have provided me.

[alhutch]

Ok thanks. I've read it also cools the car but that seems a little counterintuitive considering the name "auxiliary heater". I've read it also allows me to heat (or cool apparently) without turning the engine on since it has a fuel pumped to the auxiliary heater as well. Is this correct?

Thanks for the current information you have provided me.

You are conflating a few different functions here. You would not (and can't) run this heat when the car is off. It takes a lot of power (electric element, think space heater or toaster), so it would drain your battery in short order. Again, it is only meant to supplement cabin heat (when stone cold) until the engine coolant is up to temp and normal heat function takes over. You can tell when it's working by the sound of the relay clicking on and off when cabin heat is requested but coolant temp gauge shows cold.

You can read the recall thread from 2017 here:

https://www.audizine.com/forum/showt...-Heater-Recall

[alhutch]

Im not i have that or can control it. Do all cars have it ?.

Sent from my SM-G973W using Audizine mobile app

As far as I know, all NAR B8.5 A4's do.

https://www.audizine.com/forum/showt...-Heater-Recall

Safety recall 80C6 shows for both USA and Canada.

[MyDimeIsUp]

Intrestingly, I watched the dashcam footage while in for repair and saw they replaced my PCV diaphragm. What I'm interested in is that they placed this part on the dashboard. Can someone make out the part #. I thought it was 8T0-035-185A but couldn't find anything for it besides a "speaker cover grille" which that obviously isn't

[Theiceman]

something talked about turning it off in the MMI and i had no such function so figured i didnt have it.

[Smac770]

https://www.ebay.com/itm/OEM-for-AUD.../232649021034A
https://www.ebay.com/i/193258045037

AMI port for CAN infotainment. Would have needed to pull that to remove the glove box. I assume you do not have navigation (ie, no MMI), as the port for MMI 3G is much more basic (all the smarts are in the J794).

[Smac770]

The auxiliary (air) heater is PR 7E6. It's just an electrical heater grid that sits after the heater core to boost the air temp when the coolant is not providing sufficient heat yet (or when there's no coolant flow yet, as the N422 doesn't open until coolant is 65°C or so?). Three 333W heating elements, so roughly 25 amps each.

The wiring diagram I have has near zero intelligible info on it. There is reference to a J604 relay in the relay block under the dash (below the head lamp switch). This relay is the left one in the front row of relays. I don't even have that relay row, as the relays are for diesel or aux (air) heater. Another references says it's only in the diesel and flex fuel vehicles. For other vehicles, I see it coming off a 100A fuse in panel A (the one on the battery positive post). For 2.0 TDI, it comes off fuses in TV22, the positive jumper block in the plenum. So who knows as the documentation is incomplete.

If you did have it, there would be a plug of three sizeable wires at the bottom of the right end of the heater core housing. I assume these are the source lines to the three elements. The ground line is attached to the center tunnel right side, at the bottom of the stack.

This is different from the fuel driven auxiliary (coolant) heater system, PR 9M9, where fuel is burned in an aux heater to heat the coolant, which is then circulated with the V50 pump (vs our V51 afterrun aux pump) to provide heat. That system is interesting because it can be activated by remote. But "not applicable to NAR market".

[Smac770]

"Only vehicles with an auxiliary heater produced between April 2011 and May 2015 are affected by this condition due to the material composition of the part. Up until March 2011, a combination of tin and silver was used for the electrical connector within the auxiliary heater. In April 2011, the supplier replaced the silver with tin. In June 2015, the supplier began using the tin and silver combination again."

Bean counters saving the world again.

[alhutch]

something talked about turning it off in the MMI and i had no such function so figured i didnt have it.

Did you look under Car > Car Systems > A/C > Suppl. Heater in MMI?

Here are the instructions to disable / enable:

https://www.audizine.com/forum/showt...1#post12831632

[MyDimeIsUp]

Smac always with the detailed info!

[Theiceman]

Did you look under Car > Car Systems > A/C > Suppl. Heater in MMI?

Here are the instructions to disable / enable:

https://www.audizine.com/forum/showt...1#post12831632

yup does not exist for me. but i dont have a flex fuel car, under Ac option is only recirc on or off and synchronized control option i think.