00' Silverado no heat

[bsilverado00]

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]

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]

Originally Posted by bsilverado00

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]

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]

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]

Originally Posted by bsilverado00

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]

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]

Originally Posted by littlebitnorth

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]

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]

Originally Posted by bsilverado00

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]

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]

Originally Posted by bsilverado00

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]

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]

One more note. The hose is hot one side and cold the other but I could not find a clog anywhere...

[FrankB43015]

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.