Auto climate control on 2001 only blows really hot or really cold

S

sledandski

New member
Hi, new to the forum and hoping that maybe someone knows something about a problem I just ran into. Just bought a 2001 Limited with 97K on it which has the auto climate control. Press the auto button and the system turns on and blows nice hot air. The problem is that it never turns off, it just simply keeps blowing really hot air, does not matter if you turn the temp control down to 90 or 65 it keep the hot air coming. If you go below 65 it will switch over to AC Max mode and blow cold air, but nothing in-between. Its either all hot or all cold. Fan control knob works just fine so I have been turning down the fan as far as it will go so I do not roast as quickly, but still have to roll down the windows to keep from sweating and it is mid 20's here in Michigan. All the buttons work fine so that does not seem to be the problem like some others have had. The temp control seems to work to a degree as the system recognizes when I turn it below 65, but it does not recognize the difference between 65 and 90 and just keeps blowing hot air in this entire range. I am thinking the thermostat that tells the control unit what the cabin temp is may be to blame, but that is just my guess. Anyone have any thoughts or run into this before??

Thanks in advance for your help.

PS. sorry if this has already been addressed and I did not find it when searching.
 
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I am experiencing this exact same problem. I just replaced the control unit with a used one. It didn't fix the problem. I am thinking that the cabin temp sensor may be the problem as well. If you figure this out before I do, please keep me posted. I will do the same.
 
I have a 2000 T4R Limited with the auto-climate as well. Last winter, I experienced exactly what you are describing. For me, it turned out to be the motor that controls the opening, closing and diverting of air in the system. It is located under the passenger side dash. You have to take the motor out and replace it and then everything works like new. Hope this helps.
 
Did you guys try the self-diagnostic mode on that thing? It tests itself, the sensors and servos and reads trouble codes through the Temp. LCD--no scanner needed. Get the instructions and codes in the on-line FSM. I have a manual, so I've never tried it, but it looks pretty cool.
 
I did the self diagnostic on the control unit. got codes 11 and 21. now all i have to do is find out what these codes mean. I am going to go ask the dealer service dept. tommorrow, but i would like to find this info at a second source if possible. If anybody knows what these codes mean, please let me know.
 
StormGypsy said:
I did the self diagnostic on the control unit. got codes 11 and 21. now all i have to do is find out what these codes mean. I am going to go ask the dealer service dept. tommorrow, but i would like to find this info at a second source if possible. If anybody knows what these codes mean, please let me know.
Click to expand...

DTC-11: Room Temperature Sensor Circuit - Open or short in room temperature sensor circuit. Trouble Areas: Room temperature sensor,Harness or connector between sensor and A/C control, A/C control.

Then it gives you some tests to do with a DMM

DTC - 21: Solar sensor circuit. [will always throw this one unless car is in the sun]

Code Chart

DTC-11

Diagnostic Mode instructions

From Volume I: 4Runner FSM
 
Last edited:
Excellent find Durk, didn't know you could run a little test on the digital system. I'm gonna have fun with that FSM haha.:drummer:
 
WOW!!! That is awesome, thanks for the help Durk and Bama. I have not had a chance to play with mine yet, but I will totally check this out. Looks like I need to get my hands on the FSM too. I will let you all know what is wrong with mine when I get a chance to play with it
 
I just ordered a new Room Temperature Sensor from the dealer. It won't be here until next week. As soon as i find out if that is the problem or not, I will let you know. As for TheDurk, thank you for your assistance.
 
Success!!!

I received the room temperature sensor, went to install it, and there it was. It was unplugged. The absolute horror of it all. This is the story of how I got here. 1) paid dealer for diagnostic, $100. Informed it was a bad control unit 2) bought used control unit, $330, lost by US Postal Service. Still dealing with paypal. 3) bought another control unit, $312, installed but didn't fix the problem. 4) went on this forum, got some great advice. Ordered room temp sensor according to factory service manual this was the first thing to check. Ordered it, $37. 5) went to instal sensor just to find mine had become unplugged. 6) plugged it back in and behold! Everything work great!
I am exhausted.
 
Congrats! Glad to hear that diagnostic routine works. Now go ask for your $100 back. You clearly got some crappy service.
 
StormGypsy said:
I received the room temperature sensor, went to install it, and there it was. It was unplugged. The absolute horror of it all. This is the story of how I got here. 1) paid dealer for diagnostic, $100. Informed it was a bad control unit 2) bought used control unit, $330, lost by US Postal Service. Still dealing with paypal. 3) bought another control unit, $312, installed but didn't fix the problem. 4) went on this forum, got some great advice. Ordered room temp sensor according to factory service manual this was the first thing to check. Ordered it, $37. 5) went to instal sensor just to find mine had become unplugged. 6) plugged it back in and behold! Everything work great!
I am exhausted.
Click to expand...

StormGypsy, thanks a bunch for posting that. I have been swamped with work and finally had a chance to work on this and see what mine looked. I read your post before I started working on this and crossed my fingers for the best. Ran the diagnostic's, had code 11, took off cover and mine was unplugged too. No clue as to why, but it works like a charm now. Thanks a bunch for posting this, totally saved me ordering parts from the dealer. :trophy: :trophy: No more roasting and freezing on the way to work. Sorry you had to go through so much trouble, but it totally helped out.
 
2003 with same issue

Just bought a 2003 with this same issue. Can someone tell me where to locate
the Room Temperature Sensor.

Thanks
 
I know this is old thread, but i'm having similar issue with my 1999 4runner limited. I also know one of the previous owners of this 4runner had an aftermarket stereo installed and then removed at one point and the original factory stereo was re-installed.

I would like to check to see if the notorious Room Temperature Sensor is just unplugged. Can someone post some info on where to find this Room Temperature Sensor?

Thanks
 
takumi said:
I know this is old thread, but i'm having similar issue with my 1999 4runner limited. I also know one of the previous owners of this 4runner had an aftermarket stereo installed and then removed at one point and the original factory stereo was re-installed.

I would like to check to see if the notorious Room Temperature Sensor is just unplugged. Can someone post some info on where to find this Room Temperature Sensor?

Thanks
Click to expand...

If you look down underneath where your keys hang when they are in the ignition, look on the lower plastic panel and you will see a small "square of slits" The room temperature sensor is behind it. Sometimes, they get clogged with dirt, dust and lint. You might be able to clean it and see how it works...
 
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