Hello everyone, my name is Tolly, i'm 35, and I live in Louisville, Ky. My current daily ride is a '99 Mazda B4000 4x4, w/ the 4.0L V6, and for pleasure I drive a built motor, big turbo Neon SRT-4. I've owned both for a little over 5 yrs, the truck has been good to me, the car....well it's a money pit lol.

I've started to have a few old age issues with the truck, it currently has 141,000 miles on it. I've been lurking for a while trying to find different fixes and this site has been a big help. One thing i'm having trouble with is finding the vac leak that is causing my blower to be stuck on defrost. I did a visual inspection and couldn't find any kinks or cracks in any of the lines, so I was wondering how I would go about doing a vacume test to see if I can find the leak. I've done some searching, but none of the search phrases are finding anything related to how to do the vac leak test. I'm an electrician, and tend to take my breaks out in my truck, so with the AC stuck on defrost, I really don't get any releif(sp?) from the heat with the few minutes I have on my breaks especially when the truck is sitting in the hot sun all day. So guys and gals, any help to point me in the right direction would be greatly appreciated. Thanks in advance.

 

Okay, couple things. First, welcome to the site. Second, sorry you own a Dodge (even moreso that you own a Neon!).

Third, does it blow cold AC air? Will it also blow heat? Is defrost the only setting that works (as in, if you turn the dial, it always comes out of the defrost)?

Finally, have you had any work done on the truck? I ask because I just experienced this last week. I had some frame work done on my truck, and for some reason, he had my vacuum lines unplugged. I found that what he had done was switched the the lines that go into the little vacuum bulb under the hood.

STan

 

Well, the AC blows cold, heat blows hot, and all temperatures in between work fine also. It's just stuck on the defrost setting reguardless of the dial indicator position. I did have some work done to the truck recently, but this has been going on since the middle of winter. It was a little leak, it would ossolate(sp?) from the vent to the defrost, then I guess it just turned into a big leak, no more ossolating, just defrost now. Like I said in my previous post, I did a visual on the vac lines but saw no obvious kinks, cracks, or anything disconnected in the engine compartment, or behind the glove box. So my next step will be to do a vac test to see if I can hear it. Just now sure how to do a vacume test properly. Any help would be greatly appreciated.

 

Try switching the vacuum lines at the vacuum bulb, it "should" be located on the passenger side, below the airbox on the inner fender well. Try switching them, if I remember correctly, that's the same thing my 97 was doing.

If it doesn't work, just switch them back. It wont hurt anything.

 

Great, i'll give that a try and see what happens tomorrow. Thanks, i'll post back what I find out.

 

Defrost is the default setting for a large (generalized) leak in the HVAC system. So, it sounds like your Mazda has a large leak in the HVAC system. Check out: https://www.ford-trucks.com/forums/7...s-on-feet.html

(be sure to click the links referenced in the threads, as well).