Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

heat not blowing hot?

Discussion in 'The Garage' started by wraenking, Oct 4, 2004.

  1. wraenking

    wraenking 1/2 ton status

    Joined:
    Apr 30, 2003
    Posts:
    1,493
    Likes Received:
    0
    Location:
    Toms River, NJ
    went to go use the heat today, and i only have cold air blowing. where do i start?
     
  2. Esteban86K5

    Esteban86K5 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    3,712
    Likes Received:
    0
    Location:
    Bakersfield, CA
    Start by checking that the hoses aren't kink or clogged. Then disconnect the top and bottom hose going into the heater core and run some water through it with a garden hose to make sure that there is flow. You may find that the heater core is clogged up from years of use. I hope for your sake it isn't that because they are a PITA to change. /forums/images/graemlins/doah.gif
     
  3. 454k30

    454k30 1/2 ton status GMOTM Winner

    Joined:
    Sep 13, 2004
    Posts:
    1,613
    Likes Received:
    0
    Location:
    California, MD
    good start there! Also check and make sure that your controls are actually moving the components that decide either hot air or vent air comes in.
     
  4. wraenking

    wraenking 1/2 ton status

    Joined:
    Apr 30, 2003
    Posts:
    1,493
    Likes Received:
    0
    Location:
    Toms River, NJ
    ok, i looked behind the glove box, and the the rod (arm) that controls the cold to hot lever works fine, the one that goes from , ac, vent, heat and so forth is barely moving.

    any suggestions?
     
  5. BranndonC

    BranndonC 3/4 ton status

    Joined:
    Mar 18, 2002
    Posts:
    8,591
    Likes Received:
    0
    Location:
    Anaheim, Ca
    thermostat not running hot enough? whats the motor usually run at?
     
  6. wraenking

    wraenking 1/2 ton status

    Joined:
    Apr 30, 2003
    Posts:
    1,493
    Likes Received:
    0
    Location:
    Toms River, NJ
    she runs at about 180
     
  7. divorced

    divorced 3/4 ton status

    Joined:
    Jul 20, 2004
    Posts:
    5,115
    Likes Received:
    0
    Location:
    .
    My water level was low once and it just blew cold air.
     
  8. RustBuket

    RustBuket 1/2 ton status

    Joined:
    Feb 21, 2003
    Posts:
    1,618
    Likes Received:
    0
    Location:
    Saskatchewan, Canada
    I'm pretty damn sure this isn't your problem but its funny:

    I had enough antifreeze to go down to -40 Celcius but it went down to -50 Celcius for a few days (I live on the prairies of Canada ... /forums/images/graemlins/crazy.gif) so I just left it plugged in for the days that it was below but when I went to start it up, it blew snow!!! The heater core froze up!! /forums/images/graemlins/rotfl.gif I had to run it for about an hour to get it to thaw and blow hot again... lol..Blizzard inside the cab!! /forums/images/graemlins/peace.gif
     
  9. Can Can

    Can Can Pusher Man Staff Member Super Moderator

    Joined:
    Feb 17, 2000
    Posts:
    15,552
    Likes Received:
    136
    Location:
    Cochrane, Alberta, Canada
    Let's start here: When you switch from AC to floor to defrost can you hear a slight vaccuum hiss followed by a clunk under the dash somewhere?
     
  10. wraenking

    wraenking 1/2 ton status

    Joined:
    Apr 30, 2003
    Posts:
    1,493
    Likes Received:
    0
    Location:
    Toms River, NJ
    i hear a hiss for sure. dont know about a clunk.

    should that lever by the glove box move a lot, cause its barely moving
     
  11. Can Can

    Can Can Pusher Man Staff Member Super Moderator

    Joined:
    Feb 17, 2000
    Posts:
    15,552
    Likes Received:
    136
    Location:
    Cochrane, Alberta, Canada
    I've gotta dig up an old post of mine that explains how all the vacuum-actuated shite under the dash works. I'm willing to bet that your hot/cold door isn't opening and letting warm air in from the heater box......

    Does anybody have the post in question in their faves? It's from the 73-91 tech board.
     
  12. wraenking

    wraenking 1/2 ton status

    Joined:
    Apr 30, 2003
    Posts:
    1,493
    Likes Received:
    0
    Location:
    Toms River, NJ
    def interseted in that post

    sheel kill me if we go camping witho0ut heat /forums/images/graemlins/thumb.gif
     
  13. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Joined:
    Jul 23, 2000
    Posts:
    36,173
    Likes Received:
    1,385
    Location:
    E-town baby!
    The arm that opens that blend door is held with a plastic clip. When you go from heat to defrost that door closes and vice versa when going from defrost to heat.

    Often the little plastic clip breaks and the arm moves but the door stays partially open. You end up with weak defrost and weak heat.

    Does this sound familiar or do you get good airflow but it's cold?

    If it's just blowing cold the first thing I'd do is check the coolant level. Too many times I've found out the coolant was low...

    Rene
     
  14. wraenking

    wraenking 1/2 ton status

    Joined:
    Apr 30, 2003
    Posts:
    1,493
    Likes Received:
    0
    Location:
    Toms River, NJ
    will check all tomorrow, and give an update. so who wants to fly in to swap in my ax;es lift and tires?


    lol
     
  15. justhorsinaround

    justhorsinaround 3/4 ton status

    Joined:
    Sep 16, 2003
    Posts:
    6,798
    Likes Received:
    0
    Location:
    Northerish Phoenix, Az
    What the heck do ya need heat for? It's still like 95 degrees in the day time for goodness sake!!! /forums/images/graemlins/screwy.gif /forums/images/graemlins/histerical.gif
     
  16. Rolled

    Rolled 1/2 ton status

    Joined:
    Jun 16, 2002
    Posts:
    683
    Likes Received:
    0
    Location:
    Anchorage, Alaska
    [ QUOTE ]
    What the heck do ya need heat for? It's still like 95 degrees in the day time for goodness sake!!! /forums/images/graemlins/screwy.gif /forums/images/graemlins/histerical.gif

    [/ QUOTE ]

    Too funny /forums/images/graemlins/histerical.gif I have not used a heater in years. In fact, I use the AC, just about, every day of the year in my cars/trucks /forums/images/graemlins/smile.gif

    Another month and the weather will be perfect for the last of my Blazer projects. I can't wait /forums/images/graemlins/smile.gif Right now, it's still a bit too hot to get serious about anything outdoors...
     
  17. R72K5

    R72K5 Banned

    Joined:
    Mar 5, 2001
    Posts:
    8,905
    Likes Received:
    0
    Location:
    central IL
    sounds like plugged heater core, or incorrect routing of core hoses, or stuck closed heater core hose inline valve- if so equipped,

    if so equipped then remove it, i would anyways, but then youre in AZ so maybe it wouldnt be such a HOT idea

    if no luck iwth any of the above then make sure the vacuum hose for heater controls is connected to intake vacuum source, trace it from heater box under hood to engine, its a small plastic black vacuum tube line, without it you will have no operation of the control panel for the vent boxes assembly and flappers and vacuum diapragms but youll still have blower though btu would be cold only most likely, IE outside air only and not through heater core box unit inside cab

    if control panel position lever seems like it has very little or no resistance then the cable may have come off at one end or may have broken, but i have never seen either happen and i have had ALOT of gm trucks 67-87, and have disassembled ALOT of them too, never seen a cable break or come off, so,,.

    if i had a digicam then i could take you soem pics of heater box and cables related stuff, as i have some 73-up boxes laying upstairs that are destined for scrap after i rmeove the heater cores for their copper.
     

Share This Page