I can't help you with regards to why, but I have had a similar problem whereby sometimes when starting the van, whatever temperature is dialled in, it will be stuck at for the duration of that journey. Switching from hot to cold simply makes no difference.

I've not taken mine to the dealer yet to have it investigated as it hasn't been too much of an issue so far...

 

They are staying cool because there is no flow to the heater, the valve must be jammed. Had this on a climatronic Passat a few years back, the servo that opens the heater valve would stick.

 

Hi thanks for the replies, Chojin if it is set at a certain temp say 21 degrees how do you change it? Thanks

 

Sorry Chojin forget what i have just put in my last thread, i misunderstood what you meant about the temp being the same, i will ask the vw guys to have a look at the valve being stuck which wickedvanz mentioned, cheers both.

 

Theres a softwear update for heater controls ,dealer should know
May help but turning van of and on should reset for while ,if not mite not be a help to your problem

 

to resurrect an old thread

I've just got a 2010 tdi and the heater is a bit erratic

Put it onto Full and the heater works well (too well, its like a sauna!) turn it back one click to 26 and it just starts to blow cold

Anyone had this??

 

Hi
Did you get to the bottom of the issue with cabin heater on max to get any heat out of the vents?
Cheers Pete

 

Hi
Did anyone find the cause of the fault with the heater only blowing hot air when the temp dial is on max?
Cheers Pete

 

Same issue on mine, heard somewhate software update will solve ?
I will investigate.. Tempted to get new switch gear from fleebay

Anyone else solved??

 

I have asked this twice before. Fan speed switch works fine. Aircon works fine. Recirc button works fine. Air direction knob works fine.

It's just the temp control. Either flat out heat when turned to max or nothing at all, when turned down even slightly.
I'm quite worried about how hot the top of the dash gets too, when heat is on.

Frying or freezing, no half measures in winter.

All I have been trying to find out is wether the problem might be electrical ( presumably some kind of resistor, or mechanical ( I.e a valve , or flap jammed in the heater matrix.

Can't even work out how to disassemble dash to get to controls , come to that !

Really don't want to start pulling stuff apart, without knowing what I'm aiming to find once I get there !

Spent a lot of time on here over the years, posting to help t4 folk sort heating out, but no one seems to have been able to answer this one so far.

Love my van, but sorting things like this is a nightmare.

All help gratefully received.

Jan 2010 5.1, by the way.

 

Having the same problem, determined to sort it out. Anyone know where the heater servo valve is located?

 

I have partially answered my own question, still need to find it on the van though! No doubt buried somewhere..

Think the heater flap servo is item 52

Part list below - bear in mind this is shown for a LH drive so its a mirror image for RH drive vans.

air conditioning; for vehicles with manually; regulated air conditioner; PR-KH1,KH2,; KH3,9AP

# Number Description Qty.

1 7H1819351C air distribution housing 1
2 1J0907543A temperature sensor; evaporator; G 89; G 308 1
3 7H1819147A bracket; lhd 1
3 7H2819147 bracket; rhd 1
4 7H0819211 sealing cord 1
5 7H0819064B seal 1
6 4B0820539 temperature sensor; G 150/G 151 2
7 7H1819259 bracket; lhd 1
7 7H2819259 bracket; rhd 1
8 7E0819352 connection box; center 1
9 7H1820087C housing with evaporator; lhd
9 7H2820087C evaporator housing with; evaporator; rhd 1
10 7H0820712B expansion valve 1
11 7H0898409 air guide 1
12 7H1820139A seal; expansion valve; lhd 1
12 7H2820139A seal; expansion valve; rhd 1
13 7L0820678 bracket; expansion valve 1
14 8E0260749 o-ring; 10,8X1,82 1
15 8E0260749A o-ring; 16,7X1,82 1
16 N 10476301 socket head bolt; M5X40X16 2
17 7H0819631 dust and pollen filter 1
17 7H0819631A filter insert with odour and; harmful substance filtering 1
18 7H1819031 heat exchanger; lhd 1
18 7H2819031 heat exchanger; rhd 1
19 N 90973201 o-ring; 18,64X3,53 2
20 7H0819139 clamp spring 2
21 7L0820536 bracket 1
22 7H1815159 cover; lhd 1
22 7H2815159 cover; rhd 1
23 7H0815713 cover 1
24 7H1819422A cover; heat exchanger 1
25 7H0820119A drain tube; lhd 1
25 7H2820752 drain tube; rhd 1
26 7H1819407 foliage grille; lhd 1
26 7H2819407 foliage grille; rhd 1
27 7H1815153A housing; lhd 1
27 7H2815153A housing; intake duct; rhd 1
28 7E0959263 series resistor 1
29 7E1820021 fan; G 305 LLKG 1
29 7H2820021B fan; G 305 RLKG 1
29 7H2820021D fan; G 305 RLKG 1
29 7E2820021 fan; G 305 RLKG 1
32 7H0819059 clip 12
33 7H1819913 cover; filter element 1
34 N 10424102 hexagon head panel screw; 4X16-H X
35 7H0819731 guide rod 1
36 7H0819737 seal 1
37 7L0819133 rubber bush 2
38 N 90217304 hexagon nut; M6 2
39 7H0819058A clip; seal 1
40 7H0819037A seal 1
43 N 90999502 hex collared bolt; M6X25 3
45 7H1819939A retaining plate 1
44 7H1907511C positioning motor for; recirculated air operation; lhd; V 154 1
44 7H1907511C positioning motor for; recirculated air operation; rhd; V 154 1
46 7H1819313 coupling rod 1
48 N 10621602 hex socket oval head collared; M4X12 X
50 no replacement part
51 7L0907511AJ actuator motor, footwell flap; V 261 1
52 7L0907511AK control motor for; temperature regulating flap; V 68 1
53 7L0907511AE servomotor for side; vent; V 145 1
53 7L0907511AF servomotor for defroster; flap; rhd; V 107 1
54 7L0907511AB servomotor for defroster; flap; lhd; V 107 1
- 7L0907511AE servomotor for side; vent; rhd 1
55 no replacement part

 

Having similar issues with our heater switch too. That servo looks buried in the van. Not even sure how the system works!??I: just another tiresome niggle??

 

I have had a look and found the heater flap control servo, will post some pics later.

Ive already got all the lower trim panels off for another job so makes it easier.

Its sort of behind where the ashtray is, a bit buried. Look up from passenger footwell, towards the back of the stereo, with a torch and move the knob, you'll see it turn.

I watched it as I turned the heater control from hot to cold and back again several times. It seems like this servo could be the problem. It was a bit erratic and didn't always move in 'steps'.

It's held on with two bolts and there is one electrical plug. I think if I take the ashtray assembly out I may be able to get to the servo to remove it, if not, looks a bugger of a job. Then plan to test servo on bench and take apart to see whats wrong with it. It's a standard part used across VAG range about £70 so probably worth just replacing.

will keep you updated....

 

Awesome. I've had the lower trim off for getting to heater fan etc. Pics would be excellent if you can. Love pics!! Let us know how you get on with the servo. GOOD LUCK. T:

 

Some pics now.

Can explain further if these don't make sense.

Will probably be next week before I have chance to have a go at taking servo out but will document and post when I get chance

And here is a pic of a servo

 

Thanks Mac303 T:

I began to look the other day and started by getting to the heater controls, then realised how much further I needed to go !

Will try and find some time this weekend.

Thanks again. Will post up with progress.

 

Been thinking. Dangerous , I know.
If the flap does rotate, presumably on yours Mac, like mine, only when heat control turned to max, could it be that it's the control knob gubbins not making contact properly until dialled right round ?
Just a thought.
Hmmmm, but then why does it go cold when turned back a tiny bit ?
Talk amongst yourselves, maybe I'm losing it.

 

Good point, just ran it on VCDS and measured the 'specified value' (0%-100%) of the heater knob position against the 'actual value' (77-188) of the servo position.

At first i was seeing that when turning the knob slowly from hot to cold, the 'specified value' wasn't always matching the actual knob position and therefore the 'actual value' of the servo wasn't changing. I did a few output tests and after several times turning the knob from hot to cold and back, slowly and quickly it seems to be working properly - the 'specified value' matched the 'actual value.

Maybe you are right and the problem is with the knob or the control panel or maybe software... In an earlier post someone mentioned a software upgrade by main dealer..

The investigation goes on, will try the heater next time im out in the van when its warmed up. I will also email ross tech support and see if they have any idea.

 

It's always the main dealer gamble though, isn't it ?
If I knew that such an update existed, then may did go and talk yo them, but then, how does it 'fail" via software ? Tests gonna take more than an update to solve, surely ?
:*

 

Had a similar sort of problem recently.

Started out on cold day with heat knob in mid position. After the engine warmed the heater blew hot air regardless of heat knob position. Got to destination and parked up for half hour. Started up again and all works fine since.

I came to the conclusion that it is most likely to have been caused by Bill Gates. Just need to find ctl-alt-tel rather than having to reboot.

The van is coming up to 3 years so will be going to the dealer with niggles list including this.

 

Will be interested to hear what the main dealer says about out. Post back with what they say.

 

MD, Eurovans in Westham / Pevensey has been good about everything else in warranty so I have no doubt they will sort the last few before it expires.

Previous fixes, dodgy window switch, squeaky drivers seat & the steering knock, all done without blinking an eye.

 

Hi did you ever find a servo ? in your picture for the end of the shaft above the peddles you can see a blue tube in a foam lagging there are three of these each one has a control wire inside two go to the vent out let control dial and one go's to the heating/temp control I had the same problem could not control the heating temp but found the problem when I striped out the centre of the dash and found on the back of the heating temp dial behind the control pod there is a linkage control sprocket witch pulls the control wire and moves the heating damper open/closed this was lose as its locating shaft had busted off so it was no longer connected to the dial I managed to fix it with a plastic dowel and glue lets hope it lasts as I guess the pod would cost a lot hope this helps.....Ken

 

My van has started this today, no heat unless temperature control is up full. Mac303 did you ever get to the bottom of it ?

 

Hi mate. Did you ever get a fix for this. My t5.1 has just started to do the same .