00' Silverado no heat


bsilverado00
02-11-2008, 04:09 PM
This issue started a few weeks ago, let the truck sit for a couple of days and no heat, did a radiator flush, replaced the thermostat/water outlet. Hose into heater core hot, return hose cold. Is there anything else in that cooling loop that could cause the problem, or is the core plugged? It's an ext cab 5.3. All help appreciated.

inafogg
02-11-2008, 04:20 PM
hello if hose is cold = clogg. you can try removing heater hoses & flush out heater core.(back flush first) if this does'nt help you may need to replace.
GOOD LUCK!!

j cAT
02-11-2008, 04:23 PM
This issue started a few weeks ago, let the truck sit for a couple of days and no heat, did a radiator flush, replaced the thermostat/water outlet. Hose into heater core hot, return hose cold. Is there anything else in that cooling loop that could cause the problem, or is the core plugged? It's an ext cab 5.3. All help appreciated.
the heater core appears to be blocked.
i have 2000 5.3 dexcool coolant . when i replace coolant i have found debris only in the heater core. coolant is very clean after 5years which is my r/r cycle. so if you disconnect heater core hoses at engine thermostat and force water into heater core and reverse this should show if this was the problem. also when filling coolant keep fill cap off. run engine to operating temp could be air in system....

bsilverado00
02-11-2008, 05:22 PM
I'm thinking air in the system as j cAT said. I removed cap, let run until operating temp, had heat, both hoses hot, coolant level didn't change. I'll see in the morning once it cools down, if that solved the problem

bsilverado00
02-14-2008, 03:42 PM
Let's see, I back flushed the heater core, it's not plugged, ran it w/o cap until operating temp, as said earlier replaced thermostat, flush and fill coolant, sporadic heat, all doors on heater box functioning properly, what should I check next??????????

j cAT
02-14-2008, 05:16 PM
Let's see, I back flushed the heater core, it's not plugged, ran it w/o cap until operating temp, as said earlier replaced thermostat, flush and fill coolant, sporadic heat, all doors on heater box functioning properly, what should I check next??????????

have you had to add coolant ? i can go 2-3yrs before i add a couple of oz. if you have leak this is the only reason i can come up with. does heat return when cap is removed if so this once again could be leak or worse a head gasket and some exhaust gases getting into coolant... i hope not !

littlebitnorth
02-19-2008, 05:10 AM
Heres a curve ball for you. I have a 2001 and twice the heater has quit blowing warm air. I shut down and restarted and everything worked. Both times it was damn cold(40 below). My point is with mine it was a switch/computer issue that some how resolved itself by powering down. Just something to consider.

j cAT
02-19-2008, 12:01 PM
Heres a curve ball for you. I have a 2001 and twice the heater has quit blowing warm air. I shut down and restarted and everything worked. Both times it was damn cold(40 below). My point is with mine it was a switch/computer issue that some how resolved itself by powering down. Just something to consider.

your problem i believe is the temperature control unit this is mounted on the under dash air ducting directly above the floor hump this a common failure along with the damper door that is controlled by this componet sticking .his problem was one hose hot the other cold going to heater core... these should always be hot...temp control unit does not restrict coolant flow it only directs air flow.........

deoncollins69
02-21-2008, 09:24 PM
This make take some time but make sure the return line is not colapsing. Hose have good expansion qualities but no quality to hold vacum. Just a thought. I had an upper hose cause a cooling issue this may cause a heating issue int he core. If you do not have a colapsed hoe try finding the cabin filter cover if you have one. Pull the door and you should be able to see the core. One way or another check the surface temp. if it is hot it's fine. One other thing Do you have digital climate control? If you do it is a sensor.

gmvortec
02-22-2008, 09:54 PM
This issue started a few weeks ago, let the truck sit for a couple of days and no heat, did a radiator flush, replaced the thermostat/water outlet. Hose into heater core hot, return hose cold. Is there anything else in that cooling loop that could cause the problem, or is the core plugged? It's an ext cab 5.3. All help appreciated.


Is your water pump pumping properly, had to replace one last week, no heat same as you, not leaking or noisy it just wasn't pumping enough water round the system, impellor was corroded.

bsilverado00
02-23-2008, 07:52 AM
What I found was an air pocket in the heater core, loosened the return hose burped the air, and I've had heat for a week.

j cAT
02-23-2008, 03:11 PM
What I found was an air pocket in the heater core, loosened the return hose burped the air, and I've had heat for a week.

hopefully that air bubble won't come back!!!!!

ducati1
02-05-2009, 08:01 PM
I have a similar issue with Mine but it has a twist. I have little heat, fan speed 1 or 2 produces heat but anything more does not. Blew out the heater core last fall just in case and it was PERFECTLY CLEAN. I changed the thermostat a couple weeks ago and it was a little bit better. Everything was VERY clean inside the water pump and fuild was clean as well. The engine temp seems to be operating just fine. I have notice that if I am on the highway at over 2k rpm I have significantly MORE heat... I think the water pump is corroded. Has anyone seen this issue?

ducati1
02-05-2009, 08:02 PM
One more note. The hose is hot one side and cold the other but I could not find a clog anywhere...

FrankB43015
02-05-2009, 09:06 PM
Make sure you flush in both directions. I flushed into upper hose and out lower hose and saw nothing, switched directions and the flow was much slower, then the clog came flying out. Instant heat! Acts like a new truck again - not bad for 176,000 miles.:grinyes:

ducati1
02-05-2009, 11:38 PM
are you flushing the hose or the heater core? I flushed only the heater core... I flushed the direction the fluid goes and it seemed to flow completely free using a garden hose.
I thought maybe an air lock but the RPM makes me think the water pump is not pushing enough...

chevy393
02-06-2009, 02:46 PM
i have the exact same probelm as ducati, i have like luke warm to nothin coming out and if i put it on 4 or 5 its pointless cause it blows it so hard it turns into cold air lol. i was goin ot take it to a mechanic friend and see if he could dignose it or somthin, ill let yall know if i find anything intersting out

johnny-Z
02-06-2009, 05:11 PM
That's funny becuase my heat will not turn off in the winter time even if I turn it off or turn on the A/C. Once it's on it won't go off unless I turn the car off and let it sit for hours with the temp on cold and A/C on.

However air continues to blow even when it is turned off. Is there a vent somewhere that I need to close?

How can I get the heat to turn off once I turn it on?

ducati1
02-06-2009, 10:55 PM
I think I will try the reverse heater core blow out but I think my water pump is shot... both hoses should be hot all the time if I understand the design properly. If you are getting cold all the time it could be the trap door not moving, which I can hear mine move when I switch from cold to hot...

j cAT
02-07-2009, 02:28 PM
I think I will try the reverse heater core blow out but I think my water pump is shot... both hoses should be hot all the time if I understand the design properly. If you are getting cold all the time it could be the trap door not moving, which I can hear mine move when I switch from cold to hot...

to have only one hose hot at the heater core means that coolant is not flowing thru the heater core...reverse and fwd flush out the core there should be no resistance to the flow...there are no valves...so it this is open and free flowing the most likely cause is the air bubble.....when reinstalling hoses I disconnect at the engine then when reinstalling fill heater core as best I can,,,,,,, then hook up hoses to engine...then run engine with the fill cap off and keep filling the res....rev engine to 2-3,ooorpm a few times to get the flow/air moving to the res ..do this until engine is hot...





IF THE HOSES ARE BOTH HOT AND NO HEAT THE CONTROL MOTOR IS BAD this is in the air box next to the center hump..

slvbeard
08-07-2009, 07:33 AM
I have a problem where the temperature gauge goes up above normal, and the heat gets cold. After about a minute the temperature gauge goes back to normal and the heat gets warm. I replaced the thermostat and it seemed to work fine for about a month, but now it's doing it again.

j cAT
08-07-2009, 12:33 PM
I have a problem where the temperature gauge goes up above normal, and the heat gets cold. After about a minute the temperature gauge goes back to normal and the heat gets warm. I replaced the thermostat and it seemed to work fine for about a month, but now it's doing it again.

flush out the heater core..remove hoses at engine
flush the core out with a water hose into a bucket,,,if its black goop your gonna have to somehow cleanout all of the coolant system ..

dexcool and distilled water only....mixing of other coolants will goop up your system...

slvbeard
08-08-2009, 12:15 AM
flush out the heater core..remove hoses at engine
flush the core out with a water hose into a bucket,,,if its black goop your gonna have to somehow cleanout all of the coolant system ..

dexcool and distilled water only....mixing of other coolants will goop up your system...

Checked the hoses to the heater core and one was hot and the other cold. Pulled the hoses off the water pump and flushed them and the heater core out, working great now.

j cAT
08-09-2009, 08:45 AM
Checked the hoses to the heater core and one was hot and the other cold. Pulled the hoses off the water pump and flushed them and the heater core out, working great now.

next time the coolant is replaced,,,always flush out the heater core,,,then blow out the flush water,,,this will ensure you have heat come winter...where I live it is very important this heater core works...

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