Little to No Heat 2006 Tacoma

This is my first post here, and I'm running into a block of how to figure out what's going on with my Tacoma. A quick google search brings up a ton of symptoms and issues, so I thought I would have better luck here. I have a 2006 Tacoma that is blowing little to no heat and cool air at times. I had to replace the blower motor wiring a while back and have had some issues with the wiring since (there's one wire that just will not stay wired in the plug, which is probably my fault - any time it comes out, the blower motor stops working, I have to turn off the truck, put it back, then it works). We've been experiencing some really low temperatures for my region (8 degrees in East TN) so I was wondering if that could be part of it. The engine isn't overheating as it sits halfway between hot and cold on the thermostat and every now and then it will blow hot. I had it on this morning with the air circulating back through the cabin and I was getting some warm air, but definitely not hot. Where should I start looking?

 

First step is to check the coolant level in the radiator (not just the bottle) with the engine cold.

If that's good check your heater hoses at the firewall with the engine running at temp and the blower on high heat, they should both be hot. If one is hot and one is not you have a restricted heater core, if they are both hot then you need to check blend door operation as shown in the post below.

https://www.tacomaworld.com/threads/2nd-gen-information-diagnostics.784008/#post-28042158

 

What's the best way to check the coolant level in the radiator itself?

 

Take the cap off with the engine cold (do not open it hot) and look, the level should be pretty much even with the top of the neck.

 

I'd check the thermostat. It sounds like it is stuck in the open position.

 

So update. I checked the coolant level yesterday on lunch and noticed it looked pretty low (none in the stem). So I went home and added coolant to the system, burping it as I did just to make sure. Got it filled up, but heat still wasn't working last night. However, I noticed this morning that on my way to work, it was maintaining high heat, even at stops, and at idling. It seems that the problem has gone away. Planning to do a full coolant system drain and replacement today and heater core flush. While the problem has gone away, I did notice last night that I didn't have the same coolant that is already in it (because I had no idea what was in it when getting coolant yesterday). Just wanting to make sure it is all the same stuff. My question is this though, should I still flush the heater core at this point? Or just do the coolant swap?

 

Certainly wouldn't hurt to flush it if your changing coolant anyway.

 

That was my thought process. If I'm gonna have everything empty anyways.

 

I'm also assuming I should go ahead and drain the engine block when doing a full flush as well, correct? And lastly, should I go ahead and replace my thermostat? The one I have is working perfectly fine, but in the spirit of preventative maintenance, just wondering if I should swap it out.

 

As I was looking into it, the only reason I can see for not flushing it would be water hardness. Every video I find, people flush them with garden hoses. I don't have city water, just a well and our water is hard with a lot of minerals in it. I can't imagine this would be good to put in the system right?

 

Do NOT flush with a garden hose. Use distilled water ONLY.

 

Don’t use well water,buy some distilled water.

 

I would open at least the passenger side drain, driver's side one is kind of a pain to get without the right combination of extensions and swivels and it only holds about a quart if you drain the radiator and other block drain.
I would reccomend using distilled water and coolant concentrate or pre-mix to refill after flushing.

Thermostat is kind of a toss, if you do change it I'd go OEM. I've not had good luck with aftermarket thermostats lately at the shop.

 

You can flush with a garden hose as long as you drain everything afterwards, you just don't want to use tap water to refill.

 

Using a garden hose & just doing a drain afterwards isn't the end of the world as some are stating here....
takes pressure to remove build-up / debris.....
How much coolant did you add to top it off?
if like 1/4 of a gallon or more, ide be looking for leaks prior to doing anything......
theres no way just adding a few fingers of coolant caused your heater not to work.
so if it was low enough to cause no heat, im suspecting you need to dig further....
Just wasting fresh coolant / money if you dont crawl under it & looks for signs of leakage, stains, etc...
waterpump, radiator, heater core, head gaskets, etc....