CR140 - heater only hot on recirc?!

**1616Six** · 11-01-2018,10:52 PM

Originally Posted by Renars

Then maybe something with heater controls themselves?

It did cross my mind but if you sit the car still for ages it gets warmer until you start driving which points to it being something mechanical.

**1616Six** · 14-01-2018,09:37 PM

This is bugging me to the point of considering part exchanging the car if I can’t fathom it out soon.

does anyone have any thought as to what it could be?

To summarise...

thermostat is fine, up to 90c within 10 mins or so
water pump is fine
aux water pump is fine
heater matrix flushed
VCDS shows no faults and HVAC all working
metal pipes under the dash to the matrix are hot
rad gets hot
car never overheats
coolant looks clean

header tank was staying cold, VAG specialist found that one of the pipes to the tank had a valve inside that was blocked/broken so has replaced it with a straight pipe for the time being.

i still only get cold air blowing out. What on earth could it be?

My only thoughts now are either a blocked matrix that won’t flush out or something electrical that VCDS hasn’t picked up?

thanks

**Renars** · 14-01-2018,10:24 PM

My bet on blocked heater matrix. I think its bypass unit and flush may not work.

**1616Six** · 14-01-2018,10:59 PM

What do you mean bypass unit? Cheers

**Renars** · 15-01-2018,06:45 AM

If it cannot get through it bypases and there is no heat given to air around. Like a safety measure to kerp coolant circulating.

**1616Six** · 15-01-2018,11:07 AM

Ah I see

Well, I've just ordered a matrix so lets see if I can get it out without removing the dash..

**Renars** · 15-01-2018,10:36 PM

My 1.6 tdi CAYC golf starts blowing warm air one minute after engine start since it has electric heater like all of them have (at least I think so) I guess 2.0 tdi also have this great feature. But seems yours doesnt work either if it has it.

**1616Six** · 15-01-2018,11:55 PM

Originally Posted by Renars

My 1.6 tdi CAYC golf starts blowing warm air one minute after engine start since it has electric heater like all of them have (at least I think so) I guess 2.0 tdi also have this great feature. But seems yours doesnt work either if it has it.

Tonight I’ve stripped most of it down ready, glovebox out & bits of trim removed in preparation & I can now see the end of the matrix.

Theres a lot more in the way compared to the mk6 Jetta how to & a different matrix too. I seem to have more electrics around mine.

if I do have an aux heater then no it’s not working but VCDS isn’t showing any faults.

**1616Six** · 16-01-2018,09:48 PM

I have heat!

Appears to have been the heater matrix.

very easy to get out.. absolute pig to get the metal matrix pipes into the new matrix. Managed to get one clamp on but the other one just will not seal tight enough to get the clamp round.

After many hours of swearing at it and pulling muscles (I’m not a contortionist) I’ve given up and booked it into my VAG specialist to fit two new clamps then I can put the interior back together.

I did however start it up and somehow even without the clamp it doesn’t leak a drop so I did a good 30 mile drive and it was amazing - I was actually hot!

I am absolutely shattered but seeing the light at the end of the tunnel now I hope.