Issues with the Tacoma's Heater

Well it is getting cold, so i have been using my heater recently. This weekend i noticed after a 45 drive that it never started blowing hot air. just cold. I got in the truck to go to work On Monday and the Heat worked fine on my short 10 minute drive to work. i noticed yesterday after driving for about 20 minutes that the first 10 minutes was warm and the second 10 it was blowing cold again. i did a bit of searching and found out it make be an issue with the thermostat? i just ordered a new one and will replace that and the coolant this weekend. any other thoughts on what it could be? i have a 2009 4cylinder 4x4 with approx 105k miles. this will be the first time the coolant has been changed. any help would be great.

thanks

 

Sometimes low coolant level can create an air pocket in the heater core every so often. If this is the problem, it will of course be corrected when you replace the thermostat!

 

So if it does work or 5 minutes while driving then stops for 15 that would be the issue? The truck isn't overheating at all

 

I can't guarantee that is the reason, but it is a common reason. Easy to check.

 

Not that it's going to make any difference what-so-ever but have you ever replaced the cabin air filter? I did NOT expect to see mine was a solid brick of dirt and filth perhaps restricting airflow. Just a guess.

 

How many miles do you go before changing the cabin air filter?

 

Don't know but check yours if you haven't. I'll be keeping an eye on my new one, though.

 

Hot to cold , hot to cold , hot to cold is an indication that something is not exactly working properly within the cooling system . With most trucks , the heater core is located up higher than everything else in the cooling system and your water pump has to work harder to get the anti-freeze up there . After you do the thermostat , have a real good look for leaking anti-freeze . Pay attention to air locks when you are re-filling the radiator and overflow resevoir . Some shops offer a free cooling system pressure test . The cooling system pressure test in a nutt shell will tell you if everything including the rad cap are up to snuff .Wont tell you if the water pump is getting sleepy but it may be something worth looking into .

If you think about the boiling point of water and then think about proper operating temperature of your engine , you will notice that your engine operating temp is much higher than the boiling point of water .

For every pound on the radiator cap , the boiling point of water is raised by 3 degrees .
If you have a 16 pound radiator cap for example ,the boiling point is raised by 54 degrees to get the engine operating temperature to where the manufacturer says the engine is most fuel efficient . Just stressing how important the cooling system in our trucks actually is when it functions properly .
Should the cooling system be flushed ?
should the water pump be replaced ?
Rad cap , hoses , thermostat , cooling fins on radiator ? does the system hold pressure ?

 

Is the engine temp gauge showing normal temp while the heat isn't working? If the gauge is showing normal engine temp, it pretty much eliminates the thermostat as being the problem. If its showing below normal temps, then replacing it should cure your troubles.

If temps are normal, and the coolant level is good as "Bama" mentioned, then the blend air door / servo motor / dash control are the places to look, as well as checking that the cab air filter. (check anually and replace as needed, or more in dusty conditions)

 

Good point landphil . I didnt even think about the interior components or telling the OP to watch the temp guage .
Gotta admit , there are some very knowlegeable people here !!!

Dont think I have ever checked my cab air filter as I head to the garage .

 

the coolant is low as in none in the overflow reservoir, which is another reason why i was goign to replace/flush the coolant. the cabin air filter could use a replacement, but i replace that every 30k miles. but ya, the temp levels of the truck all seem normal. which made me think that the thermostat was ok.

 

Cabin air filters should be replaced every 15k on average. Especially in dirty, dusty environments.

Good info on the water temps and such, but remember that it is not water. It is a coolant mix which has an already higher boiling point than water at atmosphere. Raising the boiling point doesn't have anything to do with how quickly the engine gets to operating temp though, or did I misunderstand this: "If you have a 16 pound radiator cap for example ,the boiling point is raised by 54 degrees to get the engine operating temperature to where the manufacturer says the engine is most fuel efficient."

Good thought on the accuracy of the gauge. I didn't think to ask because I just kinda assumed he would have checked the gauge. But assuming is never a good idea.

If level is low, then you are on the right track. You need to find out WHY it is low. Is there a leak, or did the engine ever get hot? Prior repairs?

 

I'm hoping because I have not topped off or changed since new. I have not noticed any leaks anywhere

 

Well, you are due to change the coolant anyway, so might as well start there and get the level correct. Sometimes it doesn't take much air in the cooling system to airlock a heater core.