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Found a fix for lack of defrost/floor heat....

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Can Can, Nov 23, 2002.

  1. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Today I ripped my entire dash apart with a buddy of mine. I had to replace my instrument lights(194s are plenty bright, BTW /forums/images/graemlins/thumb.gif) and since everything was apart we took a look at why I had a lack of airflow when my heater is on either floor or defrost......

    WELL.......we ended up finding that the plastic clip that connects the vacuum operated rod to the diverter door on the passenger side was broken. As a result, the door wasn't shutting all the way and was letting most of the airflow through to the vents instead of into the defrost/floor . We used a piece of banding to screw the door back to the rod clip and VOILA, the door shut 95% of the way. I am proud to report that I now have good flow to both the floor vents and to the defrost for the first time in years!!!! /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif

    If anybody has any questions, feel free to ask. I'm not sure I explained this well enough, and if you're like me, you probably don't know about the plastic piece that I'm referring to(I didn't know about it until today).
     
  2. 85Jimmy

    85Jimmy Registered Member

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    When I fixed mine I just bought a replacement plastic clip from the dealer about $2.00 But if it breaks again I'll do what you did! Chris /forums/images/graemlins/thumb.gif /forums/images/graemlins/k5.gif
     
  3. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    All the parts stores around here were closed and I needed to improvise in order to get the truck back together. I honestly think that GM could have gone the extra mile and made the part out of steel or aluminum. My clip broke where it tapers down and screws to the diverter door- had it been made of a tougher material I'm sure the clip would never have broken in the first place.......
     
  4. 85Jimmy

    85Jimmy Registered Member

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    I think I'll have to do something like you did come this spring because it will probably break when I try to switch it when it gets to about 25deg. below 0 this winter. Chris /forums/images/graemlins/k5.gif
     
  5. Skigirl

    Skigirl 1/2 ton status

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    Paul, is that the little white thing that sits on top of that vent door in the distribution box? If so, mine's broken too. I didn't know you could buy that piece, but would like to see how you fixed it. Got pics??
     
  6. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    AHAH!!! I figured I couldn't be the only one here with the same problem.

    The clip to which i refer is found on the front of the diverter door(I'm sure we're talking about the same thing- yes, it's white). The door is powered by a spring on the top of the distribution box which forces it open and a vacuum-actuated rod that overcomes the spring and forces it closed when you switch to heat or defrost. The rod goes through a slot in the door, and then connects to the clip which is attached to the door with a single screw. I'm pretty sure that the constant pressure on the clip(in either position there is opposing pressure) is what caused it to eventually fail.

    I never took any pics(I thought about it after /forums/images/graemlins/tongue.gif), but my "repair" was pretty basic. I bent a copper 1/2" pipe band over the tall part of the clip and used two self-tapping screws to screw it into the door about 1/2" from the hinge. There's still a little play(which is why I only get about a 95% seal) but I would have to say that I more than doubled the airflow out of my floor and defrost vents.

    If a parts store or the dealer had been open, I would have tried to get a new clip, but my repair worked out better than I expected. Next time I have to get into that area I'll have the clip on hand ahead of time and install it. My only concern is that it's made of plastic, and IMHO is poorly designed.

    I hope all my rambling made sense. If I hadn't spent an hour under the dash yesterday, the description above would confuse me a little bit. Of course, I'm not the swiftest horse at the track...... /forums/images/graemlins/tongue.gif /forums/images/graemlins/wink.gif
     
  7. Suffergauge

    Suffergauge 1/2 ton status

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    I have the same problem. But I guess I just can't visulize (sp?) where this door is. I found 2, one on the pass side kick panel, and one just to the left of the glove box. Whick is the right one? /forums/images/graemlins/1zhelp.gif
     
  8. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    As far as I can tell, there's actually 3 doors-

    1. On the passenger side wall below the glove box. I imagine it's the door that allows cool(not air-conditioned) air into the cab when the heat control is set on cool.

    2. Below the left bottom corner of the glove box. This is door I'm talking about. It diverts hot/air conditioned air between the vents or the defrost/heater. This is the door that had the broken clip.

    3. Below the ashtray. This is yet another diverter that sends the air either to the floor or the defrost vents.

    Keep in mind that all these doors are hidden by the black air tubing and can't be accessed unless the tubing is removed. I also had to take my glovebox door off.

    Using the numbering above, I'll try to explain what I think happens when you switch your heater control around. I'll ignore the cool setting because most of the problems I've read about occur when people are using their heater:

    Door #2 normally sits open. This allows the air to travel through to the vents. When you slide your control switch over to defrost, door #2 closes and the air is forced into a different set of plastic tubing that feeds both the defrost and floor vents. If you slide the heater switch to floor, door #3 closes and shuts off the flow to the defrost and diverts it to the floor. Does that make sense?

    So basically you've got a couple different doors that work in conjunction with eachother. There's actually another door that controls how much heat gets through to door #2 but I think this post is confusing enough already!!!! /forums/images/graemlins/smirk.gif

    One other thing: my 84 has A/C, and the doors/diverters I'm referring to are vacuum operated. I'm not sure if a truck without A/C is setup the same way.

    I hope I'm not explaining this incorrectly. If I am, somebody please step in and straighten me out. Up until yesterday I wasn't sure how everything worked myself.
     
  9. Tweetysuarus

    Tweetysuarus 1/2 ton status

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    Good write up!
    Thanx,
    Bill
     
  10. Skigirl

    Skigirl 1/2 ton status

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    Paul - yep, same as mine. I originally tried that plastic weld stuff...that lasted about 30 seconds. I thought about doing what you did, run a piece of metal from one end to the other from the top but then decided I was somehow (and mind you I never quite thought it thru) going to run a metal strip on the underside of that plastic piece, as mine is broken one the small end tip. It really was poorly designed, wasn't it?

    It's something I definitely wanted to get fixed before I went into snow country!

    And you explained things very well. Thanks! /forums/images/graemlins/thumb.gif

    Maybe I'll take pics of mine.
     
  11. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Mine was broken in the same place, Pam. I thought about trying to reinforce it from the back too, but unless the clip is kept totally flush with the door, it won't seal when you switch to floor/defrost.

    Yeah, pics would make it SOOOO much easier to explain.....
     
  12. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Thanks for the compliment, brother!!!! /forums/images/graemlins/blush.gif

    I enjoy helping when I can. And I seem to remember this topic coming up every so often during the colder months- had know about the clip in question, I could have avoided 4 years of crappy heat.....
     
  13. Tweetysuarus

    Tweetysuarus 1/2 ton status

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    Yeah! Well some of us are even slower or more lazy than you or the temp is not that cold that it don't matter! I like the detailts of the repair!
    Bill
     
  14. Skigirl

    Skigirl 1/2 ton status

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    Good point Paul. I'm going to check around and see if I can find the part. And pics when I get started on it.
     
  15. Suffergauge

    Suffergauge 1/2 ton status

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    Thanks man!
     
  16. Stickseler

    Stickseler 3/4 ton status

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    Just to add to favorites /forums/images/graemlins/smile.gif
     
  17. I just replaced that part back in November, as my feet were freezing because the door wouldnt shut. I figure the piece lasted at least 10 years so that was ok with me. I believe the parts # is 3018715 its on my invoice as a connector, if not any dealer will know what it is, and it is a dealer only part. It cost a whoppin $1.25. Hope this helps anyone else.

    Mat
     
  18. If you look just to the right of the trans hump there is a black plastic vent cover, remove it. Once it is removed, behind it you should see the door and clip in question. I couldnt figure out why I didnt have any floor heat as I had went through my dash and fixed all the vents, repaired the vacuum lines under there and made sure everything worked. I saw that door and wondered why it was open, but that clip was broken clean and didnt look out of place. After I fixed that, I have great heat. What the door does is let the fresh air from outside into the vents, so when it shuts it diverts the hot air by it. I hope this helps. Also this is on a Suburban with AC, but I dont believe K5's are any different under the dash.

    Mat
     
  19. CyberSniper

    CyberSniper 1/2 ton status Premium Member

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    That's exactly how I fixed mine this summer when I put a new heater core and radiator in. I used a piece of galvanized ductwork though. However, mine allowed me to have defrost and floor heat but not vent heat. When I fixed it for the first time ever my vents worked and it blew out a lot of dirt, grass, mud clumps, and dust.
     
  20. fad2blk99

    fad2blk99 1/2 ton status

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    Mine broke to... This was my second Blazer (1-Jimmy and 1-Blazer actually) and both had crappy air flow. I discovered the broken clip when replacing the heater core on the second one. I got my replacement out the junkyard, but for what I went through, I would rather have made one like you did. However, fixing the damned thing was well worth it!!!
     

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