Lack of heat in cabin

S4_dan

S4_dan

Fire up the Quattro!
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As it's getting a lot cooler in the mornings now, whilst driving to work I put the temp upto 25c and it was blowing luke warm air. Temp gauge is at 90 and sits there once warmed up. I put the temp to HI and it got a little warmer but no where near how it should be.

Coolant levels are fine. No air came out of the bleeder hole, just coolant.

No faults codes indication flap motor has gone. Or do they not give codes if faulty?

A little stumped with this one. Had a similar problem last year but that was an a air lock.

Dan
 
Feel the flow & return pipes on the heater matrix, if both hot, then it points to a flap problem.
 
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I no it sound daft but you might need a re gas as it works both ways cold and hot
 
In my car before I had it re gases on cold it's wasn't cold and when on hot it's wasn't all that hot but after re gas it sorted it all cold on cold and hot on hot.. Think when the gas is full it makes the compressor work fully
 
Aircon doesn't work like that Gordy.
Do you have vcds? You can run a calibration on the motors for the flaps. One may have fallen out of sync.
 
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So why in my car after regas it's a lot hotter then before
 
Not a guru or mechanic, but it might be that since the regass the ambient temperature internally in your car has reduced due to beginning colder so the climate has sensed this and intensified the heater matrix.

Just a guess tho
 
Forgot to add that both pipes are hot to/from the matrix in the bulkhead.

I do have VCDS. Need to search on how to try a calibration setup on heater flaps. Will report back tonight on that one.

Cheers.
 
S4_dan said:
Forgot to add that both pipes are hot to/from the matrix in the bulkhead.

I do have VCDS. Need to search on how to try a calibration setup on heater flaps. Will report back tonight on that one.

Cheers.
Click to expand...
Hey Dan,
Go into HVAC and basic settings it's on the drop down as a option.
Log and clear you faults before. Then if it hits a problem on the calibration, it will flag up.
 
It goes from bad to worse!

Ok, so after my drive home from work, I plug in my laptop and scan the Auto HVAC. It came up with one code, yet there were no codes last weekend! THis was the code: 01841 - Potentiometer/Actuator for Temperature Flap; Left (G220).

So cleared the codes and ran basic output tests. Still no heat on either side.

Checked the HVAC fault codes again and got two this time. The one above and one saying no voltage to the said Actuator. Great. Clear the codes, moved the flaps and checked them in measuring blocks. Every number moved except for number 5, that remained on '225' value. No idea what the number 5 is.

Ran the output tests again and it gave a warning that my cooling fan would start, but it never did. Waiited a few mins before carrying on with output tests.

Whilst laptop was on, I thought I'd scan the Engine for any DTC's. Had two, one EGR error (cos it's blanked and unplugged) and one saying start blocked by immobiliser. Eh? It's never not started. Tried to clear them and they came back straight away.

Came out of VCDS, tried to start the car and it stalled, immo light flashing. GREAT! Tried again, the same. Removed key and tried again, same. I only have one key with the car so couldn't try another.

Plugged VCDS back in and now I had 3 codes in Engine. the to above plus another repeat of the immo block. This time, they cleared fine, and the car started! Phew. Weird.

So now I went to check the coolant hoses coming out of the bulkhead again, this time the lower hose was HOT, the top hose was about half as warm! WTF?!

Last weekend, they were both really hot. I opened the bleed hole up and coolant squirted out. So no trapped air.

What the hell is going on with my car?!?!

Why would there be such a noticeable difference between the top and bottom hoses, and why would my left flap actuator play up within 5 days?!

Any ideas please guys? I'm freezing in my car and it's only going to get colder. :-(

Dan
 
Great...after reading this from another forum........

From cold start the engine and feel the heater pipes where they go into the bulkhead. Obviously both will start off cold then one will get hot quite fast as the water is pumped into the heater matrix. The thermostat will not open yet. If one gets hot quickly and the other is a bit cooler this would show the flow through the matrix is okay. And the heater in the car will blow hot when the fan is switched on. If both pipes remain fairly cool despite the engine warming up then this would indicate the impeller on the pump is not secure. This is a very common problem on all VW group engines. The impeller stays on the shaft but turns a bit slower than it should as it slips under load. Ideally the pump should have been replaced at the last timing belt change.
However, if this checks out, it could still be a head problem, possibly cracked or head gasket, causing the over pressure in the system.



Pointing to the waterpump.....I had a genuine Audi pump fitted when I had the cambelt done in Nov 2013. So this could have been the issue I was experiencing last year.

What's your thoughts?
 
Don't mean to say it can't fail just cos it's been replaced Dan mate
 
If the stat had failed it wouldn't get to 90 and both pipes to the matrix would be slow to warm up.Both s/b about the same at this time and if one is staying cool then there is a lack of flow which maybe a good flush will sort.I would also think about taking the g/box out and checking the main flap is working and feeling if there is any warmth there.If the w/pump fails the engine overheats very quickly.My guess is a dodgy flap...they are a weak point
 
The engine gauge never rises above 90 and takes about 10 mins to get there to 90.

I'll whip glove box out at the weekend and maybe run a flush through the cooling system. Is there a particularly good flush brand or are they all about the same?

Cheers.
 
As above , any flushing agent you put in will just move all the **** to one place and create a blockage so use the back flush method, first reverse the flow then back normal etc do this a few times its the only real way of doing it without causing more problems.Make sure both matrix hoses are disconnected when you do it, I've seen ppl leave one connected and just pump all the crap into connected hose and then it blocks up again when flow is put back to normal.
 
yes.flush from cool to hot
 
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I have also heard of heating issues that were only resolved by fitting a new matrix, apparently they use an anti burst matrix, so even if it becomes fully blocked water will still flow in and out of the hoses, even flushing won't work. If you are 100% sure your water pump and thermostat are good and you have no air lock, and the flaps are working ok, this could be your issue.

Replacing the matrix is not too bad a job as it comes Out of the side of the dash without too much dismantling.
 
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Right, So I've pulled my glove box out and done VCDS adaption on me flaps. The central position flap (Black one) works but its not fully functional and throwing a fault....00601. I'll order a spare one as I've stripped and cleaned this one but still no joy.

Engine at 80c, lower bulkhead pipe was hot, top pipe was cold. There was a mild difference in the air temps between the temp on HI and Lo. Still no where near how it should be!

So, I'm now looking at the suggestion above by @Rhencullen1989 and beginning to think that it's my heater matrix which could be blocked.
I've found a guide on removal but first I will try a flush. I've ordered a drill pump and some lengths of tubing. My plan is to fill one bucket with hot water and Forte coolant degreaser and flush it through backwards with the drill pump and empty it into a second bucket. Then do a hose pipe flush in normal direction then a degreaser flush in reverse again. Then a final clean water flush in normal direction.

If that doesn't improve anything, then it looks like the matrix will need to be whipped out and replaced. Or maybe try a more caustic cleaner. It won't matter if it gets damaged as I'll just get a replacement anyway.

Dan
 
Let us know how you get on, I have read a lot about this on another er, forum (vwaudi forum) one user had flushed his matrix both ways, even removed it from the car and used some ill sounding substance through it, he still ended up replacing the matrix. Has yours been topped up with the incorrect anti freeze, as I have heard this can cause issues.
 
Mine has only had genuine coolant in it judging by the comprehensive history. I've only used genuine coolant in the 3 yr of my ownership. So I'm guessing maybe just a build up crap?

I have read the forum you are referring to above. Yes, interesting. Lol.
 
Still backflush you might be lucky
 
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You could use mains pressure from a garden hose.Should clear the main pipe but its the fine ones that are not so easy
 
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Well, after work, I set about flushing the matrix. This is the setup I used;



So, I ran some clean warm water through using a drilll pump running at 3 bar pressure. It certainly shifted something!
This isn't my coolant colour in the reservoir, so this is pretty much the contents of the matrix!



There was 'foam' like bits floating around on the surface of the water. When I emptied the bucket there was lots of rusty sludge and bits in the bottom of the bucket!

I then used some Forte coolant degreaser in the warm water and back flushed again. Then I did a normal flush with clean water and that brought a lot more gunk out. Then it was several back and normal flushes, flushed through 20 litres of cold water in the end. Refitted the lot, topped up the coolant, bled the air out then started and took the car for a run.










The result?

HOT AIR IN THE CABIN!!!

HALLELUJAH.

Not going to get too excited, because knowing my luck, it will be blowing cold again tomorrow!!

Dan
 
Result!!It might be worth doing it again before using coolant.Still time before winter.My heater has always been greatbut yours may have been abused in the past.You never know
 
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