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Thread: 91 Chevy Silverado heat question.

  1. #1
    Join Date
    Oct 2012
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    Default 91 Chevy Silverado heat question.

    I bought an old Chevy for a hunting truck about 2 years ago. Bought it in July so had no idea the heat didn't work. AC works fine. I dont really know where to start looking for the cause of the problem. Any advice on what the problem could be? Or where to start looking.

  2. #2
    Join Date
    Aug 2017
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    Does the engine get warm? If the thermostat is stuck open the engine won’t reach operating temp, therefore you have no heat.

    Second if the heater core is stopped up the warm coolant doesn’t flow through to heat the air.


    So see if your engine gets hot. If it does next would be to check the hoses coming in and out of the heater core to see if they both get hot,when you are running your heat. If only one gets hot, you need to flush the heater core

  3. #3
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    Nov 2004
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    Flapper thingy to direct air to the heater core is broke.

  4. #4
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    Nov 2013
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    Vacuum actuator

  5. #5
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    Low coolant can cause no heat too.
    Listen to your elders. Not because they are always right but because they have more experiences of being wrong.

    "We make a living by what we get, we make a life by what we give" Sir Winston Churchill

  6. #6
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    Quote Originally Posted by Gone South View Post
    Vacuum actuator
    That's it.

  7. #7
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    what the guys above have said. Pretty straight forward cooling system.
    Do you have a temp gauge? Does it get to 180 or so and stay there? If not, see if it has a thermostat in it
    and if it does, see if its stuck open.
    Should be two 5/8 hoses going to the firewall. These go to and from the heater core.
    Are they hot to the touch? If all the above, your core is clogged up or the door that switches your defrost to the floor
    vents (Actuator) isn't working and has your vents closed or the temp control lever that adjusts the temp of your heater is not
    working and the door is staying shut on the core's radiator fins.
    Last edited by ecu1984; 02-20-2018 at 01:48 PM.

  8. #8
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    Jul 2004
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    or..... previous owner had a coolant leak in the heater core, so he put stop leak in it. now, you'll back flush the heater core which will in turn reveal the leak and your windshield will fog up and smell like coolant. ask me how i know.

  9. #9
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    Oct 2012
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    The temp gauge runs on about 210 I believe after the truck warms up. I'll check the hoses next time I crank it. I have been hoping its not the heater core and didnt think it was since the windshield doesnt fog. Havent even thought about someone putting stop leak in it. Hope thats not the case. From the input you all have given me I'm leaning towards the actuator not working. I'll run down the check list starting with checking the hoses and thermostat. If its the actuator I'll have to google it to see where it is and how to get to it. I appreciate all the suggestions. I toughed it out the first winter with no heat and parked it the second and drove my daily driver. Swore to myself I would get the heat working by next deer season. I feel like ya'll have me on the right track.
    Last edited by luckydogger; 02-20-2018 at 03:41 PM.

  10. #10
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    T - I can swing by and help you troubleshoot it sometime. I’m no KRT but I can help you out shade tree mechanic style.


    Sent from my iPhone using Tapatalk

  11. #11
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    Quote Originally Posted by Johnny Reb View Post
    T - I can swing by and help you troubleshoot it sometime. I’m no KRT but I can help you out shade tree mechanic style.


    Sent from my iPhone using Tapatalk
    I appreciate that brother. I might take you up on that. Hows life treating you down there on that end of the dirt Rd? Pretty quiet out here ain't it?

  12. #12
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    Those are the easiest trucks to work on. Heater core sits right above the passenger’s feet....check the two hoses going into the firewall on the inside of the engine compartment and make sure the heater core isn’t bypassed.

  13. #13
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    Quote Originally Posted by Tater View Post
    Those are the easiest trucks to work on. Heater core sits right above the passenger’s feet....check the two hoses going into the firewall on the inside of the engine compartment and make sure the heater core isn’t bypassed.
    Bingo!

    I wish I could breathe life back in him, if I could I'd hunt him again tomorrow. - Ben Rodgers Lee

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