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Heater shut off valve

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by sting, May 5, 2001.

  1. sting

    sting Registered Member

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    If i shut off the flow of hot water to the core will this help the AC performance ? and will this hurt the
    raditor, heater core , or transmission ....any one done this I heard this increases the performance of the
    AC and makes it cool better....
     
  2. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    I'd be leary of cutting the flow to the core. It lets a small amount bypass the thermostat and preheats the radiator so you don't get into a suden dump of cold coolant into a hot block then slams the thermostat back closed.
    Check out your blend door adjustment and make sure it is closing all the way. Remove the glove box and it's easily accessed and it adjusts pretty easy. Slide the lower temp control on the dash back and forth and you will see how it works.
    There is a foam gasket on that door in the box to give it a positive seal and with age it may have disintergrated. I replaced mine with some weather stripping that was a close match from the home improvement store. I have a Tech story in the Tech section on how to get that box out to replace the heater core. it gives you a step by step on how its in there.

    Diging it in the dirt with my K5's
    Grim-Reaper
    <A target="_blank" HREF=http://grimsk5s.coloradok5.com/>http://grimsk5s.coloradok5.com/</A>
     
  3. ragtop

    ragtop Registered Member

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    I've done this for 12 years on my 81 camaro w/454 mainly so all coolant goes through the radiator to keep the engine temp down. It does seem to lower the inside temp also, plus I've blocked the bypass (water pump to intake manifold on a BB chevy). I haven't seen any ill effects but, like grim said the temp gage does bounce for a while, especially during winter, when the thermostat opens and re-closes due to the cool water hitting the block. I've had the same thing on my '88 K5 since last spring and have seen no ill effects. I think that the AC works better (cooler) this way, and I know that the engine runs cooler in stop and go traffic and when pulling my boat. I just cut the 5/8 hose from the intake to the heater and spliced in a 1/2 in. ball valve with 1/2 npt to 5/8 hose barb fittings. No regrets!

    '88K5 - 350TBI, 700R4, 208, 3.42 10 bolts w/Auburns & 31s
    Ragtop - [​IMG]
     
  4. Goose

    Goose 1/2 ton status

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    I've had one on my K5 for 3 yrs now. Grimmy has a good point tho. Never thought of that. I don't have A/C, but it keeps the interior muuuuch cooler in the summer. I do open it up every month or so and let the coolant circulate.

    [​IMG]
     
  5. DMK

    DMK 1/2 ton status

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    I ran my 69 corvette like this for 5 years no problems. Seemed to help a little.
     

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