No Hot Air From Heater

EssexAvantii

EssexAvantii

Registered User
Joined
Nov 3, 2013
Messages
28
Reaction score
3
Points
3
Location
Clacton, Essex
Hi Guys, I need to pick your brains.
Got into car yesterday and all is well however, i cannot get the inside of my car to warm up.The Mrs has noticed that since the weather has turned the car car takes an age to demist-- she just forgot to mention it!
The heater is blowing full blast out of the vent near the screen, when i switch to floor i can hear flaps move, full blast down below but, as near windscreen, stone cold air.
The expansion tank is full with water.
There are no visible water leaks.
The car heats up to 90 degrees but goes no further(Does not overheat) if anything it drops down from 90 to about 1/4 way then back to 90.
The air con is not on cold!
I have owned the car for 2 months now, previous owner said water pump changed 3 months ago but no reciept.
My car is A4 2.0 fsi petrol
All advice welcome as its got me stumped, as cold air normally means no water!
Help
:cold:
 
stat

the main flap for hot or cold may be stuck
glovebox out and check that way
or vcds scan should pick flap faults up if broke or jammed
 
  • Like
Reactions: EssexAvantii
also get car upto 90 and check pipes going to heater matrix see if there both hot
 
  • Like
Reactions: EssexAvantii
That's quick bez101!:superman:
Scan not possible yet as i don't have one,don't know anyone(cos i'm sad, boo hoo) and don't want to go to dealer unless i absolutely have to
I will try the glovebox route as this seems to be the cheap 'first look' i can definately hear flaps changing but not the hot/cold change.
 
You guys are a speedy bunch!
S4-dan i thought thermostat too. Would i be wrong in that they either work or they don't. Car does take a long time to get to 90 but as stated then drops a bit. i thought they normally seized closed and make the car overheat but either way no hot air.
Thanks for replying
 
EssexAvantii said:
You guys are a speedy bunch!
S4-dan i thought thermostat too. Would i be wrong in that they either work or they don't. Car does take a long time to get to 90 but as stated then drops a bit. i thought they normally seized closed and make the car overheat but either way no hot air?
Click to expand...

Stats are fail-safe. Meaning they tend fail in the open position so the water circulates the whole system not just the block, hence your system taking a long time to reach op-temp. As soon as the engine is not labouring, the water temp will quickly drop as the thermostat isn't closing properly to control/maintain the temp of the coolant.

Dan
 
  • Like
Reactions: EssexAvantii
under the bonnet 2 pipes
you cant miss them
if stat was gone you would still get some heat as audi normaly stick open not closed
 
  • Like
Reactions: EssexAvantii
Thanks bez101 and S4-dan for your replies.
I will go check the pipes first as that's easy, cant do the glovebox as its gonna be pitch dark in about 15 mins, so i will try that tommorow if i get home from work early enough.
 
Update
Ok guys, i ran car up to OT 90 degrees.
Its now pitch black outside! I think i found the two pipes going into the bulkhead between the battery and the servo (i had to remove the bulkhead covers) they are both hot.
I put the fan on demist and put my hand over the vent in the middle near the screen. NS is stone cold OS not quite as cold(still cold)
Does this confirm that its a broken flap or a busted matrix to you guys?
I'm thinking that the thermostat, whilst may needing replacement, isn't stopping the water flow and in turn shouldn't stop warm air through the heater.
Thanks for your patience
Tony
 
EssexAvantii said:
Update
Ok guys, i ran car up to OT 90 degrees.
Its now pitch black outside! I think i found the two pipes going into the bulkhead between the battery and the servo (i had to remove the bulkhead covers) they are both hot. So the matrix isn't blocked in terms of water flow

I put the fan on demist and put my hand over the vent in the middle near the screen. NS is stone cold OS not quite as cold(still cold)
Does this confirm that its a broken flap or a busted matrix to you guys? Do you get heat when you put the the floor vents or face vents on?
I'm thinking that the thermostat, whilst may needing replacement, isn't stopping the water flow and in turn shouldn't stop warm air through the heater. The thermostat wouldn't stop the flow of water through the matrix. It only stops the flow through to the radiator to help heat the water quickly then opens up to the radiator to maintain a steady temperature. And no, it wouldn't prevent heat coming from the matrix. But it could be the cause of the long wait to get to temp and the fluctuation of temp
Thanks for your patience
Tony
Click to expand...

So could be jammed motor flaps, ducting may have come adrift or the matrix is full of dust/debris preventing air flowing through it releasing the heat.

Dan
 
  • Like
Reactions: EssexAvantii
all vents have air flow Dan, its just cold no hot air at all
Looks like glove box off then and hopefully i can physically see whats up?
 
Either matrix is blocked preventing the heat from being pushed out (hence just cold air felt), or fan/ducting dislodged (most unlikely) or the most likely, the valve that adjust the flap for cold air feed/hot air feed from matrix is jammed/broken.

Glovebox out job and a good poke around.
 
No problem. If you need a new motor, then JamesQuattro is selling a motor from his A4....... See his advert in classifieds.....he is breaking (Sadly) his A4 2.5 Q.

Hope you get to the bottom of it.

I would still be inclined to check your thermostat though. Buy genuine not pattern as they often fail!

Dan
 
Update

Well i had the dash out ( well glovebox and the drivers knee panel) today
Good and bad news
The good news is all 5 of my motors are working i tested them whilst attached and unattached and then moved the levers by hand and they all seem fine.I also discovered why my glovebox interior light wasn't working - the switch was not attached to the hinge, easy fix.
Bad news is still no hot air at all.
So do i change the stat,heater matrix,control unit or should i just stump up for a vcds and scan 1st.
Please help other than the stat this is starting to look expensive
 
If the pipes are both hot its got to be the matrix
 
Mike B thanks for the reply please bear with me, i am not discounting any advice at this stage.If it is the matrix, i am assuming the two pipes - 1 inlet 1 outlet therefore if the matrix is busted how can they both be hot? if it was blocked as i have read elsewhere(sludge or the like) would the outlet not get hot? i'm just trying to work out how these things work so as to avoid buying stuff i don't need so please have patience
 
You must log in or register to reply here.

Similar threads

T
Hot air from heater only
Replies
6
Views
619
TheAngryDog
T
R
Heater matrix - no hot air!!!
Replies
4
Views
2K
john777w
J
J
Whining and No Hot Air Coming From Windscreen Vent?
Replies
14
Views
1K
PetrolDave
PetrolDave
S4_dan
2.5 V6 No hot air in cabin.....
Replies
15
Views
2K
Turkster
Turkster
R
Hot Air Issues?
Replies
21
Views
2K
Ronniebiggs
R
Top
Back