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Heater blowing cool

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Genegenie

Drag Race Newbie
Location
North Yorkshire
Car(s)
VW Golf
My money, but not much of it, would be on the thermostat being the cause. And I have heard of, but not actually seen, the 'silicon bag device', sounds unlikely but that is what seems to be used....
 
The Fed

The Fed

Old Guys Rule
Location
Florida
What would silicon or silicone do? I can't find an automotive coolant application on Wikipedia. And silicone is not water soluble.
 
G

Golf457

Passed Driver's Ed
Location
Guilford, UK
The Fed said:
I'll need to look again. Anyone in the States see that thing? Our bottles have a long cylindrical tube under fill cap so I think I'll need my bore scope to see past it. It looks like it's a reservoir that gets filled with something because it has a little plug on the top. I always thought we merely have long-life coolant, not a separate system to add chemicals to it.

And do have Climatronic or whatever they call the automatic climate control now? If you have the dual type, and all the vents blow cold air you could have a faulty heater control valve that lets the hot water flow into the matrix. There are two blend doors on the dual type, so I don't think one would malfunction. If you have the automatic type, VCDS should show if a door is out of position.

I think it's very strange you only experience this occasionally. To me it sounds like something electrically-operated isn't working properly, because if you were getting a blockage it seems the blockage would not come and go.
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I don't have Climatronic, mine is the basic heating. I've suspected for a while that it might be a valve that's closing off the flow to the heater matrix. But I've not poked around enough to find any valves. While it's working I'll leave it be!
 
B

branger

New member
Location
Maple Creek, sk , can
thermostat was my first guess and was gonna change it, so I called the dealer to see if I could pick one up and the parts girl said its not really a thermostat and quoted me 500 for the part that replaces or acts as the thermostat, im not paying that much money on a hunch that's the faulty part, I guess ill have to take it in and get them to fix it if I want this issue resolved, ironically one of the reasons I quit the diesel car thing was because of the slow warm up and heating , now im dealing with it anyway , can't win em all I guess, I did confirm that my car has this bag as you have pictured and looks like it hasn't broke open nearest I can tell
 
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Golf457

Passed Driver's Ed
Location
Guilford, UK
You can pull the bag out using long nose pliers, obviously being careful not to split it!

Bad news about the thermostat. I wonder if my diesel is the same.
 
A

acapvwgti

Ready to race!
Location
providence, ri
op in all of my GTIs (5) including my mk7 I always noticed if the temps outside are moderate like say 45/50 degrees out not too cold, the heater never blows really warm air. Always luke warm no matter how hot I tey to make the interior.

It’s like clockwork, every spring when the temps outside are getting warmer but I still need heat inside the cabin it never blows the hot air like it does in the middle of winter.

I even posed about it once, thinking that the heater inside somehow knows how cold it is outside. And if it’s not freezing, it won’t blow the really warm air. I’ve experienced this in all my GTIs.

Not saying it’s your issue, but I’m curious as to how cold it’s been in the U.K. when you’re having these issues.
 
The Fed

The Fed

Old Guys Rule
Location
Florida
acapvwgti said:
op in all of my GTIs (5) including my mk7 I always noticed if the temps outside are moderate like say 45/50 degrees out not too cold, the heater never blows really warm air. Always luke warm no matter how hot I tey to make the interior.

It’s like clockwork, every spring when the temps outside are getting warmer but I still need heat inside the cabin it never blows the hot air like it does in the middle of winter.

I even posed about it once, thinking that the heater inside somehow knows how cold it is outside. And if it’s not freezing, it won’t blow the really warm air. I’ve experienced this in all my GTIs.

Not saying it’s your issue, but I’m curious as to how cold it’s been in the U.K. when you’re having these issues.
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I'm thinking your system should be better. I garage my car, but it's been cold many mornings here this winter. I have enough water temp to feel warm after driving only a mile. We get heat fast from the water circulating through the exhaust manifold. Faster than any car I ever owned.

As for "automatic heat", Cadillac used to have that feature. Maybe still does, I haven't owned one since 1973. It wouldn't let the fan run until you had a certain water temp so high-society women wouldn't get cold air on their delicate little footsies. :)
 
A

acapvwgti

Ready to race!
Location
providence, ri
The Fed said:
I'm thinking your system should be better. I garage my car, but it's been cold many mornings here this winter. I have enough water temp to feel warm after driving only a mile. We get heat fast from the water circulating through the exhaust manifold. Faster than any car I ever owned.

As for "automatic heat", Cadillac used to have that feature. Maybe still does, I haven't owned one since 1973. It wouldn't let the fan run until you had a certain water temp so high-society women wouldn't get cold air on their delicate little footsies. :)
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lol you’re in FL right? You have no idea what cold is. Last week we had a stretch of weather where one day it was -4 and within 24 hours it was almost 60 degrees lol. That confuses the heating system I strongly feel.

And it’s not just my mk7 I have experienced this as I posted. It has happened in all my GTIs.

This time of year when it’s actually cold not Florida cold, the heat gets hot fast. Like a few minutes fast. Also as I have stated it’s more like late winter or early spring time temps I have experienced odd heating anomalies. Like clockwork.
 
G

Golf457

Passed Driver's Ed
Location
Guilford, UK
During my trouble shooting last year I discovered the EU288 engine heats up the engine in stages giving rapid heat to the engine jacket and the driver, then it warms up the rest of the engine before the final stage when the thermostat opens allowing the radiator to work.

This self-study guide is very interesting...

http://pics3.tdiclub.com/data/517/820433_EA288.pdf

I can't believe how good my car has been the last few weeks, since the cog-crunch, compared to last year. It was 7 deg C this morning and blowing 63C out of the blowers, compared to 43C last year.
 
Strange Mud

Strange Mud

Autocross Champion
Location
Small Town CT
Car(s)
Assorted
+1 on FL cold. I had a Mazda with the best heat I have ever had in a car....until I left SC and moved back to NH.

My rating of my 2017 GTI heat in CT is fair. a little worse than my Tacoma and way worse than my Mustang. It works but not the best.
 
G

Golf457

Passed Driver's Ed
Location
Guilford, UK
cyclops said:
No, they went straight to replacement after a few times in to investigate, they have also replaced the expansion tank, which was not part of the original plan.

It was so nice to drive home in a warm car :)
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Glad it worked for you. They replaced my expansion bottle too and flushed the matrix. For a short time it was better. Hope yours lasts!
 
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