Last week I went to get my car inspected at Jiffy Lube, and they promptly failed it, as it needed a new blower fan for the defrost. I should have asked them what they did to test the defrost, but I didn't. They basically said to go get my defrost fixed and then come back within 15 days to get the car re-inspected for free. When I got back into my car, I noticed that the fan was on its lowest setting and all the vents were open. I've noticed in the past that my airflow throughput was low, and I still need to fix that, but my defroster works fine, IF the vents are closed and the fan is run at mid-speed or higher.
After not having my blower fixed, I dropped by Jiffy Lube again (they only upsell windshield wipers on inspections, which makes them a great place to get inspected) at 8:15 this morning, with the vents all closed and fan on its maximum setting. The tech hopped in the car, felt airflow, said all was good to go. Happiness ensued.
Of course, it might not have turned out this way, and I do have to work on the airflow problem, but now I can put it off until summer when it's more comfortable to work on cars.
One last car note, if you like speeding, you'll love these pages.