VW Polo GTi heater taking too long to warm up

10 Jun 2020
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United Kingdom
I have a 2017 Polo GTi, last winter I realised it took a while to heat up inside the car (around 10 minutes of actual driving), fast forward 6 months and the car started loosing coolant and went in for a warranty repair (replaced thermostat housing) which fixed the leak.

Since the cold weather has started again and I've had the heating on, it takes 13 minutes of proper driving on open roads to get the heat to come through.

This morning my car was iced over and undriveable until I could clear the windscreen, 20 minutes of idiling and there was still no heat (despite the engine guage temp being at 90 throughout) and I had to give up and manually clear the windscreen enough to drive safely and eventually it heated up when driving.

Any suggestions on things that I can check/do myself before putting it back in the garage?

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From cold, run the engine, set the heater to hot and turn the fan off and see if the heater hoses are getting warm. If not, it could be a blocked heater matrix. Also, see whether the top hose stays cold and then suddenly gets hot - this will confirm that the thermostat is working. If it gradually gets warm, then the thermostat isn’t doing its job. If it had a previous leak, someone may have been too generous with radiator sealant and blocked the heater.
Thanks Mottie,

I did as suggested and it definitely gets hot suddenly so the stat seems to be working.

It appears that the heater hoses aren't getting any heat when idiling.

I'll have a proper dig at it tomorrow

Cheers for your help
Last edited:
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Hey John,

It was just under the max, I topped it up before doing what Morrie suggested, I will take it for a run later and see how long it takes.

I've also fired a message off to VW to moan and see if they will have a look at it under warranty, so will see what they say in reply.....I'm not getting my hopes up haha!

Being made from plastic, these housings do fail annoyingly often!
This has to raise the question, was the actual thermostat replaced with the original or did someone leave it out?
If the temperature gauge is reading 90 there is a good chance the stat is actually there but as Mottie says, as soon as the stat opens there should be a surge of heat through the front radiator.....I doubt if this would happen with the engine ticking over though, being so cool outside.
The earlier Polo’s had a bleed valve on the heater top hose but I don’t think yours has - so the heater pipes need to be red hot, both of them.
I wouldn’t expect a blockage on such a recent car.
John :)