Roof vents need replacing

if you add any additional covers over the vents, do NOT screw them down into the roof. use the available L brackets and fasten them to the edges of the vent assembly.
bumpy

Get a Fantastic vent. The fan moves a bunch more air, and the covers are lifetime warranted, you just pay shipping. Also get the Fantastic Ultra Breeze vent covers, they allow a lot more air to be moved than the other brands, and do a better job of covering the vent.

Charles

That is not a Fantastic Fan vent lid. It is the Ventline lid. You can buy them for $15. You need to remove the interior screen to access the two screws that hold the crank assembly. Then, you go on the roof and slide the old lid out at the hinge and slide the new one in place. Adding a Maxair cover is a great idea.

If they're FanTastic, they're LT warranted, you should get them free.

Not sure they are, though... Our FanTastic Fans have space-age plastic flanges and the picture shows metal. Most ordinary vents use metal.

That looks like a Fantastic Vent. And, the OP states that the fans still work!! If they are, I believe that those covers are available only from Fantastic. And you can get different "colors" from them.

I think the pic is looking at the opening end, not the hinge end, so can't be sure that they are Fantastic, but think so!!!!

Moved to Tech Issues forum from DIY.

I'm also in the desert sun and all my vents expired within 6 months of each other at the 3 year mark. I used replacement fan lids and camco vents covers. Now my camco covers are failing, which I attribute to wind and uv brittlle. I will try maxxair next.

The good news is the covers did protect the lids.

Also take some time to seriously look, maybe at PPL; you may be able to get aluminum or galvanized covers. I know they're available but have no idea what they may fit.

I'd consider also installing vent covers. Not that you need them for rain, but they do protect them from high winds and is one more level of protection from the sun.

X2 on the aftermarket covers like Maxxair. Thicker material than the OEM covers and should hold up in the sun much better plus all the other advantages.