I haven’t done this for years, but I think you can easily remove the cowl vents without removing the windscreen stainless trim. There is a row of screws under the rubber at the bonnet rear edge and a few that you get to through the grille slats at the rear. It should just pull out then.

While it is off get your hands in under towards the vent holes for fresh air and remove all the crud. Maybe give it a flush with low volume of water to make sure the drain tubes are working, check no leaks into the cabin. And when it dries out spray some fish oil or lanolin spray in there.

Edited by user Saturday, 10 December 2022 8:17:58 PM(UTC)  | Reason: Not specified

No need to remove the windscreen trim. There are 4 screws set at a 45 degree angle in the top of the grille. See the image, one is where the "1" points to the grille and I have added an arrow for the other three. Access for the screwdriver is through the slots in the grille. Once these and the 6 screws at the bottom of the grille are out it just lifts up. The passenger wiper has to come off and I usually take the drivers wiper off as well as it can be in the way a bit when you put the grille back.



It can be a bit fiddly to get the screws back in though. Blu-tak the screws onto the grille or onto the end of the screwdriver if necessary. Or you could use longer screws if it is a pain.

I agrre with KBM. Shove a needle or bit of thin wire in from the top of the jets. In my experience they block up because a bit of crud builds up near the outlet of the jet. Clear this and they work fine.

If you do take the grille off, I highly recommend what HK1837 says. Get your hand in to either side of the chamber and clear all the leaves and dirt out. Use a vacuum cleaner if you can to remove it all, maybe a brush as well. It builds up over time and doesn't clear out very easily. There is a drain tube there which blocks up and holds crud and water, end result - rust!