Where does HVAC air come in?

[Capri to ST]

I have a musty smell coming from my air vents, mostly when I use the AC, but also sometimes when I'm just using the heat. I got some Frigi-Fresh, and I need to know where to spray it in so it can get in the system and hopefully kill mold and mildew which is causing the smell. It's pretty pricey, $18.50 a can on Amazon, but I've used it before on other cars with good luck.
I'm assuming you spray it in the area at the base of the windshield just below the attachment nut for the passenger side windshield wiper and above the rubber trim molding which runs from near the base of the hood hinges. What I'm not sure is if you spray it all along the lower vent holes from side to side, or just in one or both of the more raised vent areas which measure about 4"x18" and are located on either side of the attachment nut for the passenger wiper. Or maybe I'm completely wrong and the HVAC air intake is somewhere else.
Just FYI the whole time I have had the car I have been doing the trick where you turn the AC off and let the system run for a minute or so more before you turn it off completely to let the interior of it warm up. That seems to help but I still have the musty smell.
Here are some pictures of the area I'm talking about, thanks in advance for any help

 

[CarGuy]

You are correct, spray it at the base of the windshield. That is where the fresh air is taken in. Just make sure your A/C isn't on recirculate. And I do the same thing...turning off the A/C before I turn off the car to remove any cold air from the vents. It helps prevent mold.

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[Capri to ST]

You are correct, spray it at the base of the windshield. That is where the fresh air is taken in. Just make sure your A/C isn't on recirculate. And I do the same thing...turning off the A/C before I turn off the car to remove any cold air from the vents. It helps prevent mold.

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Thanks, do you spray it along the whole area from side to side, or just into one or both of those smaller raised areas on either side of the passenger windshield wiper attachment that I'm referring to.

 

[CarGuy]

Thanks, do you spray it along the whole area from side to side, or just into one or both of those smaller raised areas on either side of the passenger windshield wiper attachment that I'm referring to.

I haven't done it on my FiST yet so just see if you can feel any suction at the vent with the blower motor speed on high as that may help you evaluate where is the best spot. I think as soon as you start spraying the picture may become more clear.

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[Capri to ST]

I haven't done it on my FiST yet so just see if you can feel any suction at the vent with the blower motor speed on high as that may help you evaluate where is the best spot. I think as soon as you start spraying the picture may become more clear.

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Thanks, I'm a crappy mechanic so I have to ask these basic questions. What you're saying makes a lot of sense, I will see if I can feel some suction, and hopefully will notice the spray getting pulled in by it.

 

[Capri to ST]

I tried CarGuy's suggestion, and looked for suction with the blower motor on high. I used a piece of tissue to look for it, and held it up against the two raised areas under the wipers as shown in the picture below, and under the narrower vents which run all the way from side to side on top of the rubber weather stripping piece above the engine. The tissue was getting pulled in by suction in all of those areas, so I sprayed the Frigi-Fresh into all of them.
I've only driven the car twice since then, but it seems to work as advertised, so far the musty smell from the air vents is gone. I talked to a service guy at the local Ford dealer, and he said they use it all the time with good results.

 

[Alkoran]

The air intake is right between the small left grill and the middle large one. The opening is blocked with some sort of filter so debris that fall in the grills don't go inside.

 

[CarGuy]

I tried CarGuy's suggestion, and looked for suction with the blower motor on high. I used a piece of tissue to look for it, and held it up against the two raised areas under the wipers as shown in the picture below, and under the narrower vents which run all the way from side to side on top of the rubber weather stripping piece above the engine. The tissue was getting pulled in by suction in all of those areas, so I sprayed the Frigi-Fresh into all of them.
I've only driven the car twice since then, but it seems to work as advertised, so far the musty smell from the air vents is gone. I talked to a service guy at the local Ford dealer, and he said they use it all the time with good results.

View attachment 30444

I'm happy my advice worked for you. You can likely use a Lysol type of product too. Anything that can help with mould, germs, etc.

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