Hey everybody, I got me a 99 Catera a few weeks ago. The good news is it runs perfectly, the bad news is when it rains my passenger floor board floods. I already know it's coming from up under the dash, but I was wondering if anyone knew a good way to fix it without going to the dealer. It floods so much that it runs into the rear passenger as well. Any suggestions?

Do you have the HVAC air filter installed? If you don't know how to check, you will find the procedure in your owners manual. My friend had a similar problem with flooding and later found it it was becuase the previous owner removed and never replaced the HVAC air filter. It wasn't a Catera though.

It could be that.. or the drain for the filter is clogged with debris like whats happened in the past. Along with the links below, check the weather seals around the door(s) too just incase.

Refer to these ...

http://www.cadillacforums.com/forums/showthread.php?t=22909
http://www.cadillacforums.com/forums/showpost.php?p=102131&postcount=12 (this has pictures)
http://www.cadillacforums.com/forums/showpost.php?p=102497&postcount=14

Thanks i'll check this out and get back to you guys.

Mine did the same thing, the drain's clogged.

Indeed, the drain was clogged. I almost took it to the dealer to. I love this forum.

This having all that water is demoralizing.Had this same problem with our 98 Catera a couple of years ago. Dealer had it for a month,took out the seats,carpet,and all and said the air cond wasn't sealed! Two years later, the same problem! I took the plastic screen shroud below the windshield wipers out and could see water at the bottom of the air cond plenum, poked around with a stiff wire and it started to drain. When it was drained,used a shopvac with thin wand to vacuum out pineneedles and other crap that had plugged the drain. In this last rainy period it has happened again, so I have cemented finer screen to the underside of the shroud to stop that"stuff" from getting in and plugging the drain again.. this just last week. Personally, I think this was the problem to begin with..not sealing like the dealer said!
Hope my experience with this problem will help you and others.