Golf blowing only cold air

Jcb21

Hi, i have a 2017 diesel vw golf and since the weekend it is only blowing cold air. Herself took it to the local dealer who said its a blocked heater. They wanted 1500 to replace this and clean the rest of the system. Has anyone come across this before and is there any way around it?

teediddlyeye

Common enough issue. Needs the flush done properly and the heater rad replaced. No way around it really.

mk7r

This is unfortunately common, there is a silica bag in the coolant bottle that bursts and blocks everything. It is a nightmare to flush out (vw make a special expensive fluid and flush kit but it doesn't always work) so replacement of the heater matrix and possibly coolant radiator and egr cooler is a more reliable fix but not cheap.

There is no way around it unfortunately. Most good mechanics will reccommend replacing the coolant bottle with the one without the bag which is identical and only about 35 euro, but for you it is too late.

Miscreant

What is the function of this Silica bag in the coolant system? It is surely not being used to control moisture, seeing as it is a coolant system where moisture is required.

teediddlyeye

https://www.boards.ie/discussion/comment/119827451#Comment_119827451

Supposedly for coolant longevity.

Although tbh I'm not convinced that the bag is anything to do with this problem. There's nothing about it in VWs TPIs and of all the coolant bottles I've changed I've never actually seen one with a split bag.

Also it only seems to be an issue on the diesel engines. Petrols have the same coolant bottle and coolant but never an issue.

I have heard there was an issue with casting the blocks and sand being left in the cooling jackets but who knows.

Also must be a reason they changed from the concentrated G13 coolant to ready mixed.

colm_mcm

@Toyotafanboi you're pretty well versed on this issue