Climate control knob issue and AC

Hi all
First post here as I just took receipt of a 99 SR5 2wd 6cyl. Having an issue with temperature knob (blue to red) subsequently impacting the AC. Anyhow, the knob won't go all the way to blue or to the left, it stops at about 11oclock which impacts the AC temp, or lack thereof. Any thoughts on where to look or what the issue could be would be much appreciated.
Thanks in advance

 

IIRC, for what it's worth, all that knob does is set the hot water control valve position, with a solid core cable. The valve on the firewall, that lets more or less water into the heater core inside the truck. If it won't go all the way to cold, either the cable is jammed up someplace, or the valve isn't aligned correctly. You can look at where the cable attaches to the valve, and, while someone turns the knob slowly from one extreme to the other, watch what the valve's control does. It's supposed to move from full on to full off, but no more.

There's a procedure on how to set the cable on the valve in the FSM. I can put the procedure up for you, if you like.
You should also check it's attachment to the knob, and it's routing out to the valve. The trouble could be at either end, or somewhere in the routing.

Good luck!
Pat☺

 

Hello there...thanks so much for the quick reply. So I have the dash apart to gain access to the control knob. In looking underneath the controller, I can see the cable you're speaking of and as I turn the knob to the left...you can tell the cable just does not want to 'go' anymore. It's attachment to the knob looks solid. I guess I'll wait for someone else to turn the knob while I'm looking at the valve on the firewall. Sorry if this is a dumb question, but is the valve on the inside or outside (engine bay) of the firewall. I'd love the procedure from the FSM if you don't mind.
Thanks!!

 

another piece of info that can prove valuable is that the prior owner said the knob used to go all the way left and AC worked fine up until 2 months ago when someone broke in and tried to steal the stereo. Based on what I'm seeing, I don't see how it relates because the cable and it's attachment to the knob are intact and cable does not seem to be bound up....I've yet to take a look at the valve yet though while turning the knob. Lastly, one final piece....the AC button remains pushed in and the green light on. I took that apart and quite can't figure out how the button is supposed to go on/off without it staying in the on, or in position?

 

TF, people are still stealing car stereos in 2021. Hope the owner had the face plate detached when it happened.

The AC button is on when the button is pushed flush in and off when its out. I would check that your control cables are working, sounds like the thief broke the climate control when they were going at the stereo. Did you pull the knobs off to make sure something wasn't physically jammed it. The cables run to the passenger side of the dash I believe, make sure they aren't twisted up.

edit: Looks like you already did that, I would inspect the valve then

 

Yeah, the cable running from the hot/cold knob to the valve Phantom Tweak had mentioned seems fine...it's not bound or tweaked in any way. That said, I've yet to run the test he recommended to ensure the cable is working the valve correctly. In regards to the AC button. The button itself is broken because it's just flush all the time...pressing it does nothing. My assumption is that's not the problem as the green light on the ac button was illuminated so I assumed that means it's engaged...is that the case?

 

So the cable indexes the valve just fine. I tried to move the valve manually but it seems as though its at a full stop already in it's current location when the knob is turned as far as it will go to the left.

 

I'm not sure whether button position or LED is the true indicator of the AC being on. Doesn't really matter in the end, if the button turns the AC on and off then its probably not the most pressing issue. You could always get one from a scrap yard if you think it need a new one.

 

Well I honestly can't tell if the AC is actually On/Off...just assumed it was On because the light was illuminated and it wasn't cold due to the location of the temperature controller. Found a button at a scrap yard down the road and I'll try that out....I have a feeling I have bigger issues though The previous owner insists it worked prior to the attempt at trying to steal the radio, etc....however what I'm seeing with the dash apart, etc...doesn't seem to make sense. Thank you

 

Here's the cable adjustment procedure. Complex as heck, isn't it?

If I were you, I would follow the cable from where it's connected to the knob, to where it goes through the firewall, and then in the engine compartment, to the valve. I suspect the crook that tried for your radio may have damaged, or maybe pushed into the wrong position, the cable somewhere along it's length. If he pushed it up out of the way, for example, and now it's routing is not correct, or it has a bend in it, it could cause the trouble you're seeing. That's the trouble with a solid core cable, if it get's bent along it's length someplace it's no longer the correct length, for the routing it should be in.
Maybe it got pulled out of the outer clamp at one end? Or partly pulled, anyway.
Does that make sense? Esentaly, since the part that actually moves, and does the work, is solid, if it gets bent, it can't recover, like a cable with a core of really small, twisted wires in it can. Like the throttle cable, for example. It only pulls, so they can use the regular, twisted core kind, and if you bend it, it just returns to what it was.

Hope this is all some help...
Pat☺

 

Well, I'm clearly doing something wrong because I was pretty sure that the cable in question that is currently connected to the knob in question passes to the right behind the glove box and then down along towards the inside of the firewall and then connects to something on the inside of the vehicle. When I rotate the knob, whatever the cable is connected to on the other side moves as well.
So you're saying that cable should pass through the firewall into the engine bay and connect there?

 

I don't understand the diagram. What is the temperature control door? Is that referring to the valve the cable is controlling or the temperature control knob on the dash?

 

The "door" is the knob on the dash, that's connected to the cable, which, IIRC goes straight out to the water valve. The "red, white, and blue" knob. I'm not sure what they call the other one, the knob that shows the pictures of where from the system the air comes out, but I believe it goes down to a "air mixer" door, but I'll look, if you desire.

Just checked. It's called the "Mode Switch". Not super helpful, but that what the FSM calls it, so you know. From what I read, it controls the "air mix servomotor". That is the device that directs the air here and there, and mixes it warm/cold depending on the selection of the temperature control knob.

Unfortunately, the book I have isn't real clear on the cables at all. All I can say is that I think the cable from "door" should go out through the firewall, and straight to the water valve. I may well be wrong, though. Did you check the cable's motion with the ignition ON or OFF? The knob not only controls the cable, but is also connected electrically to the AC/Heat system controls. Thus, as you turned the knob, it caused the system inside the firewall to move something, and that's what you heard/saw?
I bet that if you were to pull the cable off the knob, then turn the knob with ignition ON, it would move the same device, but the water control valve wouldn't move at all.

I don't know how helpful all my rambling is...
Pat☺

 

Haha...any help you provide is much appreciated as I'm kind of lost at this point. In regards to the cable that attaches to the door/knob on the dash..it definitely runs from there and connects to something under the dash (a white plastic piece) that moves when the knob is turned....that cable definitely does not pass through the firewall. It's hard to tell exactly what it attaches to under the dash as it seems to be tucked under there pretty good. I've been doing all this with the ignition OFF...I'll screw around with it ON and see if it makes any difference....
I bought a new AC button because mine was stuck in and I'm not convinced it was actually ON or not because if it were ON and the red/blue knob was at the 10oclock position, I should at least get cool air, right?

 

Well, it all makes sense now. The diagram is showing the temperature control valve in the engine bay on the firewall, it's clear as day. Unclamped the cable from the valve, moved the dial on the inside all the way to cold/blue, reconnected and clamped the cable to the valve and voila...the inside dial now moves from cold to hot. Funny enough, while doing this...control valve was so old that both hoses snapped off so ended up needing to replace the control valve..no biggie, $55 from Autozone. So with that, my AC temp now is certainly colder, but by no means ice cold....so wondering if there is still an issue somewhere? Is the most common the need for a freon charge?

 

Most commonly, yes. Look at the sight glass on top of the liquid tube in front of the radiator. Here is a chart that really is very useful.


When my mechanic went to replace the knock sensors, they bumped the water control valve taking the intake off. It disintegrated on them. So I know how that goes.
They replaced it for free, since THEY touched it and it broke. Not really their fault, it was just old and brittle, but my mechanic is super good about that kind of stuff.
They break/damage/don't repair something correctly, they fix it, no cost. One of the reasons I keep using him.
Mainly though, is that it's a 4WD shop, and ALL the people that work there LOVE their Toyotas. They all have at least one old one, and one of them used to be a Toyota shop manager. He REALLY knows Toys.

I am glad that it was as simple as an alignment, once we got all the details dealt with.

Does that help at all?
Pat☺

 

Thanks again Pat. Recharged the AC today with AC Pro and the digital gauge. Initially there was 0 pressure, recharged it back to 23 and now we have ice cold AC. Hopefully that'll do it for now...unless of course there's a leak somewhere...however I'll take the 'win' for now.