How can you unfreeze frozen windshield fluid?

The only solution to defrosting the fluid in your washers is temperature. Typically it is easy to warm up the washer bottle and pipes, as they are under the bonnet and the engine provides warmth, but the main problem is the jets (which is why some manufacturers provide heated washer jets as an option)

Removing as much ice or snow from around them helps, but you really just need to be able to warm them above the freezing point. In my car, the jet for the driver's side is directly above the turbo, so defrosting it is rapid. The one on the other side is trickier - it usually requires quite a few minutes of hard driving.

What you should be doing, however, is using winter washer fluid - this has a much lower freezing point so will be fine through the winter.

As a quick comparison:

• summer washer fluid is typically good down to around 0C
• winter washer fluids in Canada are rated to -49C
• standard winter washer fluids in Scotland seem to go down to around -15

Screenwash is water based, and it's adding alcohol that stops it freezing - which is something you do need to do, otherwise it'd freeze in the tank and potentially burst it, as well as being no use.

However when the liquid gets to the jet end of the system, and is exposed to the air, the alcohol evaporates, and the remaining water freezes. Therefore there's little you can do in very cold temperatures other than heat the system.

You could try and route the jet hoses around something hot in the engine bay, possibly by buying extended hoses and producing a DIY replacement. Also you could see if heated jets are available for any variant of your car, either higher specification of the same model or another model that uses the same jet part. Then you could potentially retrofit those, depending on the prerequisites.

Whatever you do, don't try to unclog the nozzles with anything solid. This is a sure way to break them - you may end up washing the windshield of the car behind you. Even dislodging ice from around them could be tricky because it could change their alignment.

If the clog is caused by ice, my suggestion is to find a heated parking place (like in a shopping mall or supermarket) and leave your car in there for a while (driving in the cold doesn't heat up all of your car, just the passenger compartment and the engine). After they start working again, use up all the liquid you already have and fill up with winter washer liquid. Then give it a few more squirts to push the new one into the pipes.

If the clog is just at the outside of the nozzles, either caused by dirt, or ice, you can pour some mildly hot water on them and see if that helps, and again, if it's cold, use up all the remaining liquid and replace it with winter one.