Yes! No heat? The first thing you do is check the coolant level. These trucks are sensitive to it for the heat. I'm surprised you don't hear gurgling from the dash.
Fill it up about an inch over the full line and watch for leaks.
I bet your heat will return

 

Is nobody else worried he might have a cooling system / heater core problem? Coolant doesn't just dissappear and that is substantially low. If you haven't had recent work done that involved draining your cooing system, you are likely leaking it from someplace. This should really be checked by a pro. Any chance your hvac system smells off (fishlike)? Any hard to remove fogging on the windshield when you try to run the heat? These are normally signs of heater core leaks. After that you might want to get your whole system tested for leaks. This can be done with uv dye if a leak isn't obvious. I'd bet that if you fill it your problem will go away but return shortly after it releaks. Cooling is not something to take chances on.

 

Is nobody else worried he might have a cooling system / heater core problem? Coolant doesn't just dissappear and that is substantially low. If you haven't had recent work done that involved draining your cooing system, you are likely leaking it from someplace. This should really be checked by a pro. Any chance your hvac system smells off (fishlike)? Any hard to remove fogging on the windshield when you try to run the heat? These are normally signs of heater core leaks. After that you might want to get your whole system tested for leaks. This can be done with uv dye if a leak isn't obvious. I'd bet that if you fill it your problem will go away but return shortly after it releaks. Cooling is not something to take chances on.

yep, that's why I said check for leaks. post #5
And yes, somehow coolant does just disappear over time. I understand the systems that aren't completely closed (overflow bottle) it can slowly evaporate. But even our trucks seem the loose coolant very slowly over time. My truck for example has "lost" about 2 inches of coolant over the 5 years I've had it. I know for a fact it has zero leaks. One of those unexplainable things that happen in our world I guess Either that or it had some air in it when I bought it and it took a long time to escape out of the system. This seems a bit unbelievable but no more unbelievable than coolant disappearing I guess.
But yes, always check for leaks when it's low.

 

Added coolant last night. Heat is back! Now why it was so low to begin with is a different story.

 

I would just keep a close eye on it. Look under the truck every morning too after your drive.
Ever see anything under it?
Don't be surprised if it a bit low again after driving it. Just add again to an inch above the full line. After a few heat cycles it should stop going down.
Good luck with her.

 

Heater is disabled until engine warms up. It’s an EPA thing.

This is disabled at a certain temperature. Like below 30F then the heater works right away. But above that then the heater waits for engine.

In other words no. That should be plenty of coolant even if not at the line. If there is a problem it’s not that.

 

Thermostat sticking??? And why are you low on coolant?

 

Not sure. Just happened to check today. Haven't noticed any problems other than I heat not getting warm. Just started getting cold enough to notice.

 

how your heating system works
it might sound a little funny, but your vehicle’s heating system is a part of its cooling system. the cooling system circulates a coolant through the engine that absorbs heat. that heated coolant then runs through the radiator, where the heat dissipates. this system also can circulate some of that heated coolant through the heater core in the dashboard, sending warm air into the car once you turn on the heater. the amount of hot air and which direction it blows are controlled by the buttons and switches on your dash, which direct the heater valves and the car’s blower fan.

Heater Blowing Cold Air? Here's Why, and What to Do About It

 

There was a bulletin on gurgling

 

Heater core leaking is normally recognized immediately by wet carpet and antifreeze smell inside the cabin. My experience with other vehicles has taught me that coolant has to be super low for heat to not work but maybe Colorado’s are different. I always go to the thermostat first. It’s an easy enough job, it’s cheap, and they usually go sooner or later anyway so it saves you overheating on the road later.

 

Heater core leaking is normally recognized immediately by wet carpet and antifreeze smell inside the cabin. My experience with other vehicles has taught me that coolant has to be super low for heat to not work but maybe Colorado’s are different. I always go to the thermostat first. It’s an easy enough job, it’s cheap, and they usually go sooner or later anyway so it saves you overheating on the road later.

Not near as easy as keeping the coolant at the proper level.

 

Check the weeping hole on the water pump (maybe cover it with talcum powder or flour). I had this same issue with my Lexus. It leaked out enough to drop the coolant level (and my heater would stop working). I could never figure out where the leak was because it was evaporating and not dripping. Finally stole my wife's make-up mirror and spotted the leak.

 

Check the weeping hole on the water pump (maybe cover it with talcum powder or flour). I had this same issue with my Lexus. It leaked out enough to drop the coolant level (and my heater would stop working). I could never figure out where the leak was because it was evaporating and not dripping. Finally stole my wife's make-up mirror and spotted the leak.

Interresting but what does this have to do with coolant leaks??

 

It's all good! I do too. I just didn't want to respond like an a$$ if you were serious.

I just couldn't see the leak just by looking directly.

 

Like said above even if not related to heat problem you should add coolant a half inch or so above the full line just to be sure you won’t someday hear that gurgling sound.

 

I do have that gushing water sound from time to time. Just read the bulletin and it sounds like what it describes

 

Put the system under some pressure and let the truck run up to operating temperature while looking for leaks. It will build more pressure as it warm up so plan accordingly to stay within the safe zone, ie not too much pressure once warm.

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