time for my heat problem thread...
 

i know these threads are popping up left and right here, but i don't want
to hijack someone's, and with these cars, every problem is special and relies heavy
on the specifics.

RE-EDITED to clean it up at a little bit.

symptoms:

-no heat from any vent while driving, in any mode, and with air directed at any vent.
-there is heat at idle, but only with low fan speeds (1-4) if fan level is increased (9-12) it'll
start to blow hot but within 20-30 seconds it's basically cold again.
-water temp gauge in car is always rock solid a 90 degrees

what's been checked:

-heater core valve block has been replaced with one from an 09'. i need to double check the part numbers because
one digit might off different from the one i changed.
-VAGCOM has been ran in autoHVAC and there are no error codes
-system has been bled - reservoir cap off and bleeder nipples on heater core hoses
-heater core hoses are hot, even inside the cabin
-while doing output tests in the vagcom, when checking V68 and V71 HVAC hot air would flow out of single dash vent to the
right of MMI screen, but can only be checked at idle.

so yeah, that's where i'm at.

I'd read the troubleshooting procedure in the service manual. Maybe your friends down the street have access to one if you don't already have.

If you have heat through the dash => the core is fine.
It's the flaps air mixer is stuck or broken.
Go to settings => set the vent all the way to hot to see if the vent changed.
I think you have heat, it's just the vent flap doesn't let the hot air through the VENTS.
Let me see if I can get something out of the Elsa.

"If coolant circuit is not completely bled after filling, air may accumulate in heater cores of A/C unit, thus reducing heating performance of air conditioner, additional noises may occur or customer may complain of different air temperatures flowing out of vents at driver's side and front passenger's side despite identical setting.

Corrective action:

– Sent the ventilation system to maximum heat output (temperature selector to “Hi”) for the driver and passenger sides on theClimatronic control module -J255-.

– Perform a lengthy test drive at high engine speed (at least 10 minutes, engine speed above 2500 rpm). In doing so, select a low gear to prevent excessive vehicle speed.



<a href="https://www.dropbox.com/s/mc2ve5m532rjn3o/a8_heat.pdf?dl=0">Check heat pump</a>

Control and Regulation Components Inside Passenger Compartment

Note

t If there is a malfunction in the system, first check the Climatronic control module -J255- DTC memory (and the rear A/C display control head -E265-) using Vehicle diagnosis, testing and information system -VAS 5051 A- in the “Guided Fault Finding” function.

t If no fault is displayed, check the measured value block for the Climatronic control module (and the rear A/C display control head ) and activate the affected component with the “Output diagnostic test mode” function of the Vehicle diagnosis, testing and information system -VAS 5051 A- in the “Guided Fault Finding” function.

t Repair work on refrigerant circuit, refer to → Chapter „Refrigerant Circuit, Repair“.

t Perform the following work after completing repairs using Vehicle diagnosis, testing and information system -VAS 5051 A- in the “Guided Fault Finding” function:

– Check DTC memory of Climatronic control module (and of rear A/C display control head ) and erase DTCs displayed if necessary.

– Check coding of Climatronic control module.

– If necessary, check adaptation of Climatronic control module and rear A/C display control head (not installed on all vehicles).

– Perform air conditioner basic setting.

t The electrical test for various actuators, potentiometers and sensors is described in Guided Fault Finding of the Vehicle diagnosis, testing and information system -VAS 5051 A- in the “Guided Fault Finding” function.

<a href="https://www.dropbox.com/s/fjkceq8juam5ndf/climaticcontrolj255.pdf?dl=0">ClimateControlJ255 removal</a>
<a href="https://www.dropbox.com/s/qg3ixhaylyjq07k/j255debug.pdf?dl=0>J255debug</a>


Cheers and good luck,

Louis

i basically only have heat at idle. i can't go output tests while driving
because the vagcom disconnects as soon as i start to roll. that's why im
not sure because i don't know how i can get that flap/valve to open while
i'm driving.

how do i get into the climatronic module with the vagcom? i don't see an option
to get into that.

A legit VAGCOM/VCDS?
 

A legit VAG COM-VCDS cable from Ross-Tech, or a knock off eBay special? If the latter, get a real one. Fakes lead predictably to don't really work. Go ahead and use any largely worthless knock off in the toilet tank next time the chain breaks on the stopper.

If a real one, look at Ross-Tech site for instructions--what functions work with key off, key on, engine running; how to use measuring blocks; system self test routines (at least some of which only seem to work once per test/hook up cycle); how to do instrumented recording during a driving run, etc.

oh man, i knew i wasn't man enough for this car!
the vagcom cable i have is legit.

another thing i noticed is when the car is at operating temp and i'll
switch to "AUTO" and put the temp to "HI" on both sides it's basically
does nothing. it's barely blowing in air, if i put the manual fan button it
at 3.

you would figure if you crank everything to HI and AUTO it would be
blowing in full tilt?

The flaps that direct the flow of hot air don't work...
 

Can you try to turn on the A/C with the setting to LO to see if you get air out of the vent?
If it doesn't then, find the recycle mode to close the outside air to see if you have air coming out.
I think the flap controller is stuck at position that NOT allow air through the cabin.

<a href="https://www.dropbox.com/s/inlk8mm5aft5g6f/airguides.pdf?dl=0">AIR GUIDES</a>
<a href="https://www.dropbox.com/s/rjqbkq0xa40tqdn/airrouting.pdf?dl=0">Air Routing</a>
<a href="https://www.dropbox.com/s/gzd5dma2esa60pi/control_regulation_components.pdf?dl=0">Control and Regulation of components inside</a>

so yesterday i brought the car in the garage at work to let it defrost.
i opened up all the windows and let the car reach the same temperature
everywhere so i could check all the air temp sensors. everything seemed
good.

i brought the car back outside and let it idle for like 20 mins on AUTO. when
i got into the car, there was HOT heat coming in through the defrost vent but the
fan was blowing it pretty low. as soon as i started to drive it started to get
progressively colder and colder until there was nothing left.

Was the fan still blowing on low? I didn't see it but is your fan always blowing at a decent speed (variable?) Or is it always low?