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2000 Silverado not blowing heat

This is a discussion on 2000 Silverado not blowing heat within the Technical / Maintenance forums, part of the General Discussion category; well i just recently bought another 2000 silverado and i noticed tonight because it was really cold out and i ...

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    Registered User OneBaddAssZ71's Avatar
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    2000 Silverado not blowing heat


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    well i just recently bought another 2000 silverado and i noticed tonight because it was really cold out and i had the heat running that the heat in the truck really wasnt blowing that hot. it was blowing like luke warm air. i checked the coolant and all that stuff is right where its supposed to be. the truck doesnt overheat or anything. i know it aint burning antifreeze because i do not smell it burning and the oil isnt discolored so i know its not anything mechanical far as the motor or cooling system on the truck. im just wondering what could possibly keep the truck from blowing hot air.

    i know in my old 2000 silverado my lifted one the heat in that truck would run you out of it. the cab got so nice and warm, and it just doesnt seem like the heat is working like it should on this truck.

    also what im wondering is if the cabin filters could be clogged up and causing it not to blow hot.

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    Registered User Jewild's Avatar
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    Re: 2000 Silverado not blowing heat

    Is it a temperature thing ?
    Or a blower thing ?
    You do or do not get the blower to change all speeds ?

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    Re: 2000 Silverado not blowing heat

    I had the same problem on my 2000 GMC. I flushed the radiator with Prestone Radiator Flush from Wally World and it started blowing hot when I got done. I guess the heater core was stopped up. Who knows? It works now though!

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    Re: 2000 Silverado not blowing heat

    My guess is your thermostat is stuck open, which allows the coolant to flow through the radiator all the time. Which keeps the coolant cold enough so it doesn't give off enough heat as it passes through the heater core. Flush the coolant, change the thermostat and fill it with a good coolant/water mix for the upcoming winter. Should operate exactly as you need it after that.

    I'd recommend a switch to regular green coolant too in the process, some people will say stick with dexcool (orange stuff, ethylene glycol) but it's overpriced, mislabeled coolant that offers no more protection and cooling ability than properly maintained green at almost half the cost. It's listed as long life coolant but has been known to harden and rot out gaskets if not properly maintained or flushed.

    Let this not be a dexcool or no dexcool debate. This is simply how i feel, do as you wish. You are not gonna kill your motor either way if you take care of it.


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    Re: 2000 Silverado not blowing heat

    It's that time of year again, and this thread subject will become a regular in here.

    Start simple:

    1.) Gain access to the cabin air filters to ensure they aren't packed up with debris and dirt and are able to flow air through them. Clean or replace if necessary

    2.) Ensure that the heater core isn't clogged. Check the two coolant hoses passing through the firewall on the passenger side. Both should get hot when the engine temp is up. If one is warm or even cold, then you have a blockage in there and simple take a garden hose, remove the hoses, and use the garden hose to flush and backflush the heater core. That tends to fix that issue.

    3.) HVAC tends to be an issue on these trucks. Ensure that the actuators and gizmos for the HVAC system are responding to your requests from the air flow and temp knobs on the dash.

    With all three of these simple to check and correct if needed areas working as they should, you will get great heat into the cab.
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    Re: 2000 Silverado not blowing heat

    thanks. ill try the thermostat first. how hard is it to get to the thermostat on these trucks. i know on the obs they are easy to get to. and i never had this kind of problem with my other nbs.

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    Re: 2000 Silverado not blowing heat

    Quote Originally Posted by Tweaks View Post
    It's that time of year again, and this thread subject will become a regular in here.

    Start simple:

    1.) Gain access to the cabin air filters to ensure they aren't packed up with debris and dirt and are able to flow air through them. Clean or replace if necessary

    2.) Ensure that the heater core isn't clogged. Check the two coolant hoses passing through the firewall on the passenger side. Both should get hot when the engine temp is up. If one is warm or even cold, then you have a blockage in there and simple take a garden hose, remove the hoses, and use the garden hose to flush and backflush the heater core. That tends to fix that issue.

    3.) HVAC tends to be an issue on these trucks. Ensure that the actuators and gizmos for the HVAC system are responding to your requests from the air flow and temp knobs on the dash.

    With all three of these simple to check and correct if needed areas working as they should, you will get great heat into the cab.
    the knobs are responding all the controls are working on my truck so i guess it narrowed it down to the 2 u posted above

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    Re: 2000 Silverado not blowing heat

    Yeah, pulling the cabin air filters out and seeing if they are clogged up is a good thing to do anyway. I doubt it will change the perceived temperature, but it will certainly improve airflow performance through the vents. I just did it with the 02 2500HD and it was blowing like it never did before (that sounds incredibly wrong ).

    I still think it's the thermostat though, they are relatively cheap and you might be able to get away without flushing the entire system. I've done it both ways (flushing prior to replacement and not) and i've never had any issue.


    1983 Jimmy Sierra Classic-Future LSX Swap Recipient
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    Re: 2000 Silverado not blowing heat

    i believe ill prob just do both, change the thermostat out, and flush the system, plus change the cabin filter. just a little cheap insurance because if that core is stopped up it can bust. or even freeze in the winter and bust and ill have to take the whole damn dash out to replace it
    Last edited by OneBaddAssZ71; 10-03-2010 at 06:30 PM.

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    Re: 2000 Silverado not blowing heat

    I've got a 99 that did that last month. Did a system flush and all is good.
    1999 Silverado ECSB W/T . 4.3L . 115K . 2WD . Storm Gray Metallic
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    Re: 2000 Silverado not blowing heat

    well i checked the hoses this morning after i had drove it about 16 miles. the temp gauge was sitting right where its supposed to be. and i even left the truck running and opened the hood to check the hoses and none of the hoses were hot. they were barely warm to the touch. i checked the core hoses going thru the firewall and i checked the upper radiator hose as well. both were the same. so i imagine its probally the thermostat.

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    Re: 2000 Silverado not blowing heat

    I think you are close to sorting it out. Thermostats are cheap maintenance. I haven't had to replace one but I think they sit in the water pump assembly and are relatively easy to access and swap out. You will be dropping coolant for sure with this project so while you are at it, pull those core hoses and backflush for the heck of it. Refill with new coolant and you should be all set.
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    Re: 2000 Silverado not blowing heat

    well today i put the new thermostat on, and let me tell you its a pita to get to. but i got it replaced and i also flushed the heater core out and put some fresh anti freeze in. and that done the trick. i cranked the truck and let it sit idol for a few minutes, checked all my fittings to make sure they wont leaking and then i drove it up the road and the heat will run you out of it now.

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    Re: 2000 Silverado not blowing heat

    Nice!!! Thanks for the follow up.
    00 RCSB Z71/JBA cat-back/Z71 Tahoe valance/EBC slotted&drilled rotors with SS lines & SS braided hoses/Edelbrock headers/BB tune/6000k HID low beam & fog lamps/Auto-headlight disable mod(nice)/Vette servo/LT1 E-fans/LED gauge cluster/Titan 18" wheels/Rollpan/Belltech rear sway bar/2-4 drop

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    Re: 2000 Silverado not blowing heat

    Glad to see it solved the problem and was cheap. Just didn't know how hard it was to get to on the LS-engines. I know the older small blocks and 4.3L are fairly easy to get too annd can be changed in 5 minutes.


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    Re: 2000 Silverado not blowing heat

    the thermostat is on the front of the motor on the water pump so in order to get to it you have to remove the airbox and intake tube, the fan belt, and the lower radiator hose connects to the thermostat so when i pulled the lower hose coolant went everywhere, on the older style chevys the thermostat was on the intake manifold itself, and the upper radiator hose connected to it. but it was a complete pita. i got er done tho

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    Re: 2000 Silverado not blowing heat

    when i did mine i just pulled up on my oil change ramps and that in addition to holding the hose up when i took it off i didnt loose a terrible amount of coolent

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    Re: 2000 Silverado not blowing heat

    yea i didnt loose all my coolant out of the radiator. because i did elevate the hose, but i did loose all the coolant out of the ressy

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