My 01 4Runner has inconsistent heat

Hi all, I just joined this group and hope someone has ran into this issue I have. Basically sometimes it blows hot and most times is does not, I recently put a new t-stat in it and verified it worked before installing, I have back flushed the heater core and have consistent heat in the hoses going in and coming out and noticed when I turn it from hot to cold and back sometimes that will make it blow hot, the blend door actuator appears to work but the heater control valve doesn't always open up all the way and I can manually pull it open and that still doesn't always make it blow hot, today when I tried my rear heat I heard a faint clicking/ crackling noise while driving that sounded like it came from the dash or blend door actuator and of course the rear heat works fine. I have a new heater control valve on order but now I'm not sure that's the issue, besides the heater control valve and the blend door actuator what else should I check ? Thanks in advance!

 

Does anyone see my post ? Am I doing something wrong ?...it only shows I've had 1 view and others after mine have many.

 

It's being seen but so far no one has had a suggestion to proper, or they would have. Hang tuff and someone may come along with an idea or two. Good luck.

 

The two parts you're looking at are what I would have suggested. I'm not super familiar with the 3rd gen yet. Not like I am with the first gen. Of course, that may be because I've had my 2 87's for over 30 years now, and the 99 for less than a year. But I'm getting there.

I would be concerned about a "crackling noise" coming from ANY where. You need to investigate that.

When you put the new water control valve in, make certain you align the cable going out to it properly. It's very easy to do, and quick as well, but pretty important. There's a good "how-to" in the FSM for that. I can post it up for you if you need it.

Good luck to ya!
Pat☺

 

I've got a similar issue with my 97. No noises and everything functions as it should. I can flush the heater core and heat works great for a month or so. I was going to replace the heater core, but at 288k the ac still works great. I'm waiting for the ac to go and I'll replace the heater core then.

 

Have you tried one of the chemical flushes out there?

Second, and more important, to my way of thinking, are you burping the system properly when you flush the heater core? You really should flush the entire system, and ensure it's burped properly when you do. All it takes is an air bubble in the heater core to stop the flow through it. No heat.

Also, the heater core fins often get clogged up with dust, dirt, leaves, and so forth. It's easy to take the box off from around the heater core and blow some air back through it, against the normal air flow direction. Beware, there will be dust, etc, flying everywhere, so wear safety glasses and a decent dust mask, or you'll regret it. The FSM has a good "How-to" for removing the box around the heater core.

Take care, all!
Pat☺

 

I have tried all of the above. I still only get a couple of months of heat with a complete flush.

 

It is a long shot but have you tried the OBD to see if it is throwing any codes?

 

I think the rear heater coolant lines are prone to rust. Saw a pick on here about it. Check’em out?