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  1. #1

    Default very upset! (heater core!)

    well as i posted during thanksgiving break I successfully flushed my heater core which had been clogged for an unknown amount of time, and it has been working miraculously since, until about two days ago.....

    I noticed my passenger side of my windshield would just NOT defrost all the way AND when i turned the heater on it smelled like coolant, and the heater nor vent, or any combination of defrosting methods would work. well it wasnt until today driving my usual 23 miles to work in amazing texas drizzly, cold weather, that i kept trying and trying to defrost my windows short of rolling both windows all the way down, that i noticed the smell was just ridiculous, and defrost was not working in any possible way, i looked over on my passenger floormat and boom.

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    here is how i drove 23 miles to work, it was very uncomforting...
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    so now I am faced with the utmost reality of a leaking heater core , im sure all of you know what is entailed in this replacement of a simple $40.00 piece of equipment...


    i have seen youtube videos and writeups, and all the sort but am just scared to attempt something this huge, but at the same time, would not trust any mechanic to properly reinstall every single bolt and screw, because they always forget something small...
    what do you guys think i should do? do it my self and lose a weekend of my life, or pay the intimidating price of ($800.00-up) for a mechanic?
    who has done this?
    any advice?
    anything else that should be checked while this is being performed?
    god help me...
    2000 Chevrolet Silverado

    4.3L V6, 4L60E, 2WD, Single Cab
    Airaid CAI
    Poweraid TB Spacer
    Flowmaster 10-series exhaust (dumped)
    Edge CS insight monitor
    4.10 gears
    Limited-slip differential
    LS-1 Dual Electric fans
    Corvette tranny servo swap

    Head Unit: Alpine
    Speakers: Alpine SPR-60C 6.5" component set, 4X6 Infinity Kappas
    Subs: 2-12" Kicker CVT's
    Amps: Alpine-M1000 (subs), Alpine MRX-F65 (Speakers)

    305/70R16 NITTO Terra Grapplers
    16" PROCOMP 7089's
    2" leveling kit
    3" Fabtech Spindle Lift Kit
    Front/Rear-Bilstein 5100 shocks

    35W HID Low Beams
    RECON LED smoked roof cab lights
    HELLA LED taillights and 3rd brakelight
    HELLA FF-75 Aux. Reverse Lamps
    RIGID dually D2, flush mount, wide beam
    Hawk HPS Brake pads
    Russell braided steel brake lines
    Powerstop-red powdercoated brake calipers
    Powerslot Cryo brake rotors
    EGR in-channel window visors

  2. #2


    when mine went I just put bars leak in it. It stopped leaking and was still fine when I sold it a few years later. If I was going to keep the ruck I would have fixed it properly. The only thing that really sucks about the job is that you have to evacuate your A/C system. Other than that it just takes time.

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors,
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

  3. #3
    TRPLXL2's Avatar
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    Jan 2009
    Norwalk, Ohio
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    It's really not as hard as you would think, pull the dash out and the havoc unit is right out in the open. You can do it!!!
    2004 Chevy Colorado
    LS1 5.7 swap/TBSS rear axle swap

  4. #4


    I'm with @Pikey, there is a time and a place for leak seal; but, if you want to tackle the dash, I found this with a google search:

    1. Disconnect the negative battery cables.
    2. Remove the instrument panel trim panel.

    1. Remove the following components, depending on how the vehicle is equipped:

      • The IP cupholder cover, shown
      • The IP cupholder Refer to Cupholder Replacement.
      • The floor console extension Refer to Console Replacement (Base Console) Console Replacement (Luxury Console).

    1. Remove the data link connector (DLC) (1) from the IP assembly.
    2. Remove the driver side knee bolster.
    3. Remove the lower IP trim panel. Caution: Refer to SIR Caution in Service Precautions.
    4. Remove the passenger side air bag module.

    1. Remove the knee bolster deflector.
    2. Remove the steering column.

    1. Disconnect the body control module (BCM) (1) from the bracket.

    1. Pull out the left side accessory switch bracket (1).
    2. Disconnect the electrical connections.
    3. Remove the IP Cluster.
    4. Remove the radio.
    5. Remove the HVAC control assembly.

    1. Pull out the right side accessory switch housing.
    2. Disconnect the electrical connection from the right side accessory switch

    1. Unbolt the IP upper brackets. Disconnect the wiring harness from the right upper bracket.
    2. Disconnect the following electrical components as necessary from the IP assembly:

      • The remote control door lock receiver, if equipped with remote keyless entry Refer to Remote Control Door Lock Receiver Replacement in Keyless Entry.

    • The IP wiring harness junction block
    • The right side courtesy lamp
    • The IP cluster lead-Unclip the component from the IP assembly

    1. Disconnect the parking brake release handle from the IP assembly.

    1. Disconnect the following electrical components:

      • The automatic transfer case module (1), if equipped
      • The fuse block from the bracket
      • The body wiring harness junction block from the bracket
      • The left side courtesy lamp

    1. Remove the nuts (4) and screw (3) holding the IP assembly (IP) (2) to the IP carrier sup


    '09 Avalanche LTZ - Black
    '05 Envoy XL (sold)

  5. Likes 99'HEARTBEAT liked this post
  6. #5


    :/ hope mine doesn't go bad over the winter. Is be dumping a tube o alumna seal in it to get me till spring lol

  7. #6


    Well I guess I'll be attempting this myself then.....
    but a little update as of now,
    So there must be some decent sized leak because right above my passenger defrosting vents the window is constantly fogged almost like there is constant heat coming through those vents, once my engine heats up, kinda right above where the heater core is obviously.

    And today about 2 miles before I got to work on my 23 mile drive, some kind of smoke starting creeping through my vents..... Not like fire, but possibly coolant burning off on something and getting into the vents, anyone know what could cause this? Once I got to work I popped my hood and noticed there is also coolant leaking pretty much right where it is on the inside of my truck but on the frame rail underneath the firewall

  8. #7


    Probably water vapour coming through the vents. Remember, the system is under presure and as the water excapes from the leak, it is turning into a vapour. That tells me it is not a huge leak, just a small crack. Get a tube of Prestone Stop Leak or Bardahl Stop Leak they both work. I prefer the Prestone, but not everyone does.

  9. #8


    can anyone reccommend i replace anything else while dong this? My A/C has always had a leak, and had a dye test performed at a local shop and nothing was found under the hood, so must be the EVAP unit behind the dash??? Not sure but speculating, just dont want to have to do this job twice if you know what i mean... dont know what else might be age fatigued behind there.....

  10. #9


    Quote Originally Posted by reggiecab2000 View Post
    can anyone reccommend i replace anything else while dong this? My A/C has always had a leak, and had a dye test performed at a local shop and nothing was found under the hood, so must be the EVAP unit behind the dash??? Not sure but speculating, just dont want to have to do this job twice if you know what i mean... dont know what else might be age fatigued behind there.....
    A couple of items to look at replacing, are the Heater Hoses, and the Quick Dis-Connect fittings for them, where the heater hoses go into the firewall, and also both of the Cabin Air Filters,

    Here's a Video showing how to remove the Quick Dis-Connect, and the tool needed to remove them,

    Also this would be a Good Time to Clean out the Drain Tube for HVAC, its number #35 in the Diagram

    Here's the Quick Dis-Connect Tool, for the Heater Hoses

    EDIT.....I going to add, for items to look at replacing......the Thermostat
    Last edited by 99'HEARTBEAT; 01-02-2014 at 06:35 PM. Reason: Added Infor.


    5.3 l 3.73 l G80

  11. #10


    thanks for that heartbeat!, I just did my thermostat maybe 300o miles ago so it is good, and yes planning on doing the cabin air filters too, but thanks for anything else you can add, i will be driving to san antonio tomorrow just to perform this task so if you can think of anything else before me please let me know!

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