I started to have a problem during the summer with a leak on the passenger side floorboard when I ran my air. It stopped for a while, but now it's started back when I turn on the defroster. I have to turn the fan on high for it come on.
It's starting to get cold I need heat. What do you suggest the thing to check?:

 

My guess is the A/C drain is clogged up. FYI, the A/C runs when on defrost.

The drain is a rubber tube sticking out of the firewall ob the passenger side engine compartment.

I don't understand " I have to turn the fan on high for it come on".

How is the heater affected?

 

Welcome to the site, check out post number 9 in this thread

https://www.chevyhhr.net/forums/prob...et-help-57785/

 

OB question about the video, did he send his wife/gf up under the car to clear the drain?

 

Toes have nail polish. Finger has big diamond.

You can use canned air and you might be able to get to it from the top.

Assuming the " I have to turn the fan on high for it come on" means the only fan speed that works is high; you need to replace the fan resistor pack.

 

I didn't cast or shoot the video so ???

 

Mine has done this several times over the years. I just remove air cleaner to get easy access to the rubber drain line on the firewall and just pinch it with my fingers a couple of times and all of the water will drain out.
Last time I put some water and bleach (50/50 mix) in a spray bottle and squirted some into the rubber drain to free up any algae built up in the drain pan, problem gone.

Fan on high will pick up water in pan and blow it into the ventilation system.