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Blower Not Producing Hot Air

ruu1989

New member
Location
Edinburgh, UK
Hey, attached a photo of inside the reservoir - how does that look?
 

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Yani

New member
Location
Bucharest
You don't need to "remove most of the dash" to replace the heater core. Price quoted seems very high. If there was that much corrosion the car would overheat. It's relatively easy to tell if the heater core is clogged.

Hi all,
I find me in a very similar situation as ruu1989. Golf Mk7 TDI 2.0 (2013) w/o any DTC and also w/o any hot air in the car.

Could you please elaborate in detail, what is the actual method to check the if the heater core is clogged or not?
Also maybe there is a solution/substance/mix that combined with a fully flush of coolant would unclog the heater core?

Until now the tests that I've run were as follow:

1.Check coolant level - OK
2.Check coolant temperature in the instr. cluster / OBD - OK (constantly 90 degrees/ 87-89 degrees in OBD)
3.Check the hoses that are enter into the dash - warm - next step is to buy a infrared thermometer and measure them. Also I don't get it why there are 3 hoses there)
4.Coolant color is almost like the Ruu's one. A few months ago the coolant light comes on and I've refill the coolant reservoir with G13 + distilled water.

I want also to mention that from time to time w/o a pattern or frequency car is producing a mixed sound just like a gagging with a beating that seems to come from driver's feet somewhere. (Is that related to the HVAC issue?)

Neither on left or right side, there is no hot air. Trying all the possible combinations (A/C ON + HI TEMP / A/C OFF + HI TEMP etc.)

Ruu1989 please update us with the latest news.
I will try to do the same.
 

ruu1989

New member
Location
Edinburgh, UK
Hi All,

Have been meaning to update since last week but haven't had a chance.

Basically I'm back to getting a good amount (but not perfect) of heat after a steam/pressure flush of the whole system, and brand new coolant. There was apparently a technical service bulletin issued on the 2013+ golfs last week for this exact issue - perhaps someone who knows how to look these up (my Google-fu failed) could share this? Something to do with (and I may be wrong/misquoting what I was told) a small of silicon in coolant bottle bursting and then corrosion happening, or something.

The current state of my car is that I've got 'good enough' heat after a flush, which only cost me three hours labour, and to restore 'full' capacity it's likely that the coolant bottle and heater matrix will need replaced, and possibly the heat exchanger, too. This'll be around £700 for parts+labour, but given the heat I have now, I'll probably defer this at least until next summer.

Drove up through the Scottish borders last night with -9c outside temp and car was nice and toasty - was amazing.
 

Yani

New member
Location
Bucharest
Nice and warm

Hi All,

Have been meaning to update since last week but haven't had a chance.

Basically I'm back to getting a good amount (but not perfect) of heat after a steam/pressure flush of the whole system, and brand new coolant. There was apparently a technical service bulletin issued on the 2013+ golfs last week for this exact issue - perhaps someone who knows how to look these up (my Google-fu failed) could share this? Something to do with (and I may be wrong/misquoting what I was told) a small of silicon in coolant bottle bursting and then corrosion happening, or something.

The current state of my car is that I've got 'good enough' heat after a flush, which only cost me three hours labour, and to restore 'full' capacity it's likely that the coolant bottle and heater matrix will need replaced, and possibly the heat exchanger, too. This'll be around £700 for parts+labour, but given the heat I have now, I'll probably defer this at least until next summer.

Drove up through the Scottish borders last night with -9c outside temp and car was nice and toasty - was amazing.

Hi again,

I have some additional misunderstandings about your comment.
By heater matrix I understand that you refeer to the heater core which should be changed (the one located into the dashboard). Also I can't locate and understand what heat exchanger is. Would you be generous to explain that for me ?

On other hand, did you flush one time, or 2 times (the second time only with distilled water?) and what did you use for refilling (e.g. VW OEM G13 coolant - photo attached). Also how many liters did it take for the refilling (for both coolant and distilled water)

Last note - if someone has a DIY guide for flushing and changer the heater core and heat exchanger please help me. I tried to find on google but nothing showed up.

Thanks,
 

hollygosh

New member
Location
Suffolk
Same issue

I have the same issue with my gtd, but the passenger side has ice cold air and hot air...the drivers side only gives off like warm. There is a reset you can do which meant the drivers side got hot for a few minutes then back to like warm again. Coolant all looks fine, right level right colour. Mine is still under warranty but not factory...they will only pay £45 an hour for labour, the whole cost of parts but no diagnostics. Anyone recommend what to do? Am I best looking myself or getting a plug in and trying to find the fault or do I just take it to a backstreet garage and hope they can fix it? Any comments welcome! :eek:
 

baldybouncer

Newbie
Location
Wrexham
I have the same issue with my gtd, but the passenger side has ice cold air and hot air...the drivers side only gives off like warm. There is a reset you can do which meant the drivers side got hot for a few minutes then back to like warm again. Coolant all looks fine, right level right colour. Mine is still under warranty but not factory...they will only pay £45 an hour for labour, the whole cost of parts but no diagnostics. Anyone recommend what to do? Am I best looking myself or getting a plug in and trying to find the fault or do I just take it to a backstreet garage and hope they can fix it? Any comments welcome! :eek:

I have the same issue! been told its sensors in the vents - but not been able to check yet!

https://www.youtube.com/watch?v=zm1HRU64Dpo

Anyone done the above on a mk7?
 
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Yani

New member
Location
Bucharest
Hello all,

I revert to you with fresh news about my Golf VII TDI 2.0 - 2013.
I was in different services and the last one assured me that the heater exchanger is clogged, and therefore it should be replaced.
The test was simple:

1. Using VCDS they diagnose if there are any blocked flaps (there is a button which re-adjust all the flaps). - test done, nothing changed.
2. Check under the hood, if the hoses that enter in the firewall are hot - both of them were hot.
3. Using a T20 torx screwdriver, they opened a plastic cover located at the bottom of the driver seat, near the acceleration pedal. After this part was taken out, the heat exchanger metal pipes can be seen. I touch both of the pipes - one was very hot (probably 90 Celsius degree) while the other one was warmish.

Other symptoms: a very powerful noise of gargling could be hear from time to time (without any frequency or specific factor). I believe that the reason for is the fact that a lot of coolant is blocked in the heat exchanger and under the pressure a big quantity is passing over the debris.

These days I will go there to replace the heat exchanger and coolant.
I opt for Motul Inugel G13 (simple not ultra version) because is a coolant ready to use (already mixed with distilled water)
Also, as a procedure I will drain the system and put only distilled water 2 times in order to circulate through the system make it as clean as possible.

Hope this helps you guys.
 

anon234

New member
Location
wales
I found this thread searching for 'mk7 golf no heat from vents'.

Lots of the results on google say that the dashboard has to be taken out to get to the matrix.

That is not true, you can get to it by removing the glove box. Here is a video (not mine):


I've removed everything apart from the heater core itself, I'll get the garage to do that bit (even they said they'd need to take the dashboard out).
 

Lth0ms0n

Go Kart Newbie
Location
United Kingdom
Car(s)
2013 Golf GTD
So, while driving home this evening, I noticed I was getting cold air from the car - even with the Climate set to HI.

I always drive with the HVAC set to Auto so I took over, set it to face vents and then noticed that the driver’s side was blowing cold but the passenger was hot.

I drive a 2013 GTD I’ve had since new, have recently taken to doing some DIY on it but nothing major (yet). The A/C has recently been recharged and works fine, I just don’t seem to get heat from the driver’s side.

For how long, I’m not sure.

Reading through this, I can confirm:

- Car heats to 90 degrees and stays there
- Coolant is a clear pink colour and level is fine
- Strong heat available from passenger side, currently not sure about rear vents or the foot wells
- A/C working fine but have noticed a strange ‘plastic’ smell coming from it since it came back from having that done

Based on this, I’m leaning towards it being a problem with the blender door that mixes hot/cold air for the driver’s side. Would you agree?

UPDATE: Have done some testing this afternoon, prior to attempting any work on the car (I have obtained a Haynes manual for it so I have some form of guidance before attempting) and I can confirm that with the auto off so I can control it fully, all three air outlets on the passenger side are fully functional and produce piping hot air. On the driver’s side, it’s lukewarm at best.

I would have thought the warm air coming off the matrix would be split into the 2-zones afterwards, not at the same time, in the hopes that this isn’t a problem with the matrix - can anyone confirm if I’m right in suspecting that?
 
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Lth0ms0n

Go Kart Newbie
Location
United Kingdom
Car(s)
2013 Golf GTD
So I've been re-reading all of this, totally forgetting I was the last person to reply to this. It might be a bit of a long post...please go with me on this.

Since the day I posted that comment, I have done LOADS to the car but we're only about 50-60% of where I'd like to be with it. We get hot air from the car (sometimes) and there have been days were the far-right vent (car is RHD) is almost as warm as the far-left (According to OBD11 reading the temperature sensors) but they have been few and far between.

I've since done a full de-grease and flush of the car. We ran 800ml of Forté bio-degreaser through it and after around 300 miles with that in the coolant, the vents did begin to warm up.

Before: After:

1621022771628.jpeg
1621022871672.jpeg


Not a massive increase but the only change in the testing was the use of the degreaser. So it was dislodging something!

We then dismantled the matrix from the heater box and checked it out - when we filled it with hot water while investigating it, the thing heats up evenly, meaning it can't be blocked.

I will say, my situation is different - I had the silica gel back in the coolant bottle but it wasn't ruptured.

1621022957870.jpeg


There also wasn't any sand in the system. All I can assume was causing it was the breakdown of the glycerine in the G13 coolant...collecting in the core.

Or, so we thought...


My Dad and I have been working extensively on this, ever since - we've really got the bit between ourselves on this and have basically deduced that THIS is the problem:

1621021804045.jpeg


Perhaps not the best picture, but hear me out. I can only comment on models with Denso heaters in them but given the problem affects both, I think it's safe to assume the same applies.

The hot coolant flows into the bottom of the unit then works it's way along the bottom, up and then out the top. I can't confirm exactly when my heating broke but we're both pretty certain that it happened after July of 2019, when the water pump in my car was replaced along with the timing belt.

The reason for this is that since flushing it out, I have noticed that I get considerably more heat from the car after I release the air pressure (and any accompanying bubbles) from the coolant system when the car has been running for a while. This has been the pattern since we drained it, took it out, replaced and re-filled it - albeit only with water, for now. I don't want to put coolant back in until we're certain the problem is resolved adequately.

Dad's a mechanical engineer and is of the same opinion as I am - because the coolant flows in and out of the same side of the core, if an air bubble gets trapped in there, due to the angle it's sitting at, any water + air which gets trapped in the matrix following the draining of the system will arrive at a state of equilibrium - with the water trapping it inside. Since the water will always find the path of least resistance, the air is likely going to collect on the far end of the matrix and stop it warming up to the correct temperature.

This would explain why it still gets warm but immediately cools down with enough air blown through it.

VW have designed a bad system here, plain and simple. I highly doubt that we'd be seeing the same thing if the inlet/outlet pipes on the matrix were on opposing sides; one bottom left and the other top right. That would force the water, when it's being filled, to work it's way all the way along, then up, forcing any air out so that it can find it's way up to the bleeding tubes, on the top of the engine block.

I am convinced that this is the reason why so many people never get their heating working again after they've had this problem - the system is physically incapable of evacuating the air which naturally works itself in here. Having an engineer for a Dad means we're never short of...imaginative...ways of trying to resolve this. In some ways, it's fun but the entire time we've been working on this, I've always ended up being right and I'm currently grappling with him over the use of a vacuum pump to empty the system entirely and then re-fill it (as the Haynes manual recommends) to see if the system behaves any differently.


I share this only to bring my experience here. I appreciate there is a lot of insight into this issue with lots of different, varying experiences, but I can't help thinking that so many of these cores have been thrown out unnecessarily. When I tell you that mine warmed up evenly after we ran hot tap water through it, I mean it - there is no blockage in mine anymore. And it does work when it's in the car, we just can't make it do so consistently.

Yet.

I mean it when I say that every time I've had a solution to this, I've ended up being right. This is only worth commenting on because computers are my thing - not mechanics. That's Dad's area. But I am definitely of the mind that VW's "self-bleeding" system is perfectly fine for bleeding the engine block & radiators but this thing, stuck in the bowels of the dashboard, is absolutely the black sheep - the unfortunate, "gimpy" one.

Curious to know what other people think. This is absolutely still a work in progress. We had it working, perfectly - we had de-greased it, drained & flushed it and re-filled it. The fun started when we drained it to flush it again (because the engine was still full of de-greaser).

It has to be an air bubble. There is nothing else wrong with my car - miraculously. She is in tip-top condition and it really surprises me, given how many miles she's done.
 

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Ian83

New member
Location
Pennsylvania
Car(s)
2015 Golf SE
Hey guys, posted this on Vortex but wanted to update here (original quote included):

Problem resolved! It was the coolant control valve which is located (buried!) on the crankshaft/clutch end of the engine block (driver side). On the 1.8 TSI motor, it is hidden behind a hard turbo pipe. Access is difficult but not impossible. My mechanic tested by removing the valve and simply joining the two rubber hoses. Heat! Almost immediately. The valve is not cheap, about $US 150, but it has resolved the problem. I think the old valve was "stuck", but would start to move after hot coolant on the engine side hose warmed it for more than 10 minutes. But that's way too long for the winter season coming. VW part # for that valve is 4h0 121 671d
[/QUOTE]

Just wanted to make sure I came on here and backed up this solution. THIS ALL WORKED on my 2015 Golf SE! Sure enough it was the coolant control valve. I bought this exact part, VW quoted me at different locations for $500-$650 in labor charges to replace this part. Talk about absolute garbage - first of all, this part should be covered - 2015's clearly have a known issue and they don't want to admit it. VW charged me the stupid $99 diagnostic test and suggested a solution that probably wouldn't work which was the coolant flush, yet another $100 for that and then the overall solution which was replace the entire heater core. What a joke! I'm calling VW to dispute this ineptitude. I'm not kidding - you'll find more solid answers and beneficial/accurate information here than from most VW mechanics. It's unreal how many times they try to rip you off at dealerships for problems with very simple solutions.

Long story short - my local mechanic has a son-in-law who worked at VW for 16 years and now works at Audi, but he moonlights a bit during evenings using the local garage space for side jobs. He quoted me $190 for the labor costs, said it was actually super simple and easy, and I tipped him $20 just for getting it in early. Part VW # 4h0 121 671d for that valve absolutely did the trick - I have totally operable heat, comes in in minutes like it should in freezing temps.

**** for context - my morning commute is one of the most consistent things in my life. Last April, suddenly during a super cold morning in PA, my front windshield was iced over lightly and all that was blowing was cold air for 15-20 minutes. I drive about 45-50 mph max during that time on regular roads. At about 20 min, I get on a turnpike which allows me to go 80 mph. This builds the temp and pressure in my car to the point where lukewarm air was blowing and finally cleared my window. A few times I tried turning the car on and off and that seemed to work for a while until it didn't anymore. Then once I got off the turnpike, oddly enough, the heat come on blazingly hot. This came at about 45 min into my commute - obviously NOT helpful. On the way home, I usually got heat faster since I got on the turnpike much quicker, but this got old quick. Fast forward to this fall when I finally started needing it again, I tried to find a solution via VW as stated above. PLEASE MAKE SURE TO SEARCH THESE FORUMS before ever going through with a repair - it will save you hundreds, if not thousands, once your car is past warranty. And that's no thanks to Volkswagen and their stingy warranty for this model - 2015's had the most useless 3 year warranty. Everyone knows most major problems don't spring up in that time.

I just wanted to thank everyone here in this awesome community that made it possible for me to solve my issue by standing on the backs of your experience and knowledge. Could not have done it without these forums and again, I just wanted to thank everyone who chimed in with the part #s and outcomes. That experience, trial and error and money spent helped us all and I really wanted to express my gratitude. Kind of unreal that we have to come on here to figure it out for ourselves instead of talking to the "should be" experts at any VW dealership.
 
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