2002 4Runner – Temp Control only has Hot Air Output

[jonfasch]

Looking for help on a 2002 SR5 4Runner – 321,556 miles – have had it 14 years as my primary vehicle. A wonderful truck!

Recently the top 2 lights (wheels) in my 4WD indicator stopped working, and also an A/C Evaporator (Condenser) Drain Hose was leaking on my carpet. This site helped me fully resolve both issues…. I am eternally grateful.


So now I have another issue.

My temperature control is ONLY putting out hot air. Was working fine last week.

History and T/S:
-Vehicle has always switched between heat and cool in the past.
-Past summer, AC was serviced, but lost its coolness within about 2-3 months. (FYI - I fully feel this is a separate issue than the rest of this post)
-Over the winter my Temperature Control knob was acting flaky, and air flow was switching between cool / hot / more than it should. To resolve, I kept having to turn the Temp Control knob all the way left, and then all the way right, to get it to heat right.
-2 months ago, I pulled the Temp Control module and sprayed the back/inside with QD Electronic Cleaner. Fully resolved issue, and the heat/cool worked normally till this week.
-This past weekend I had the Blower Fan out to resolve a bearing noise when cold – cleaned the Blower Fan/Motor fully and works fine now.
-But it seems at the same time I was working on the Blower Fan (rt side of Passenger area below the glove compartment) and the A/C Evaporator (Condenser) Drain Hose leak … the Temp Control (lt side Passenger area) now only puts out hot air no matter where the dial is.
-Air temp control servo motor at bottom passenger left doesn’t move when Temp Control is turned from hot to cold or vice versa. I think this operates the vent door to switch between hot and cold air. I’m hearing no clicking or any sound or seeing any movement from it.
-Fan Speed Knob and Air Output Selector Knob functionality work fine, just issues with Temp Control Knob functionality
-Pulled the cable in the Engine compartment where the cable attaches to the water valve, and I can easily manually move the lever. Putting lever all the way to the left, air started blowing cooler again.

Based on what I understand, there are just a few things that could cause this:
1. Temp Control module/rheostat bad
2. Heater Control Servo Motor bad
3. Vent Door stuck
4. Seized cable to engine compartment

Questions:
1. What are my first steps in this?
2. Are there any fuses that could be causing this?

Any other thoughts on this?

Thanks,
Jon

 

[jonfasch]

I have some thoughts about how to proceed… As I really don’t want to take it to the dealer yet…

1. Pull Heater Control Servo Motor and test if cable can be moved inside the vehicle to control the water valve in engine compartment, or if it is seized.

2. Pull Heater Control Servo Motor and test with a battery.

3. Pull Dash Climate Control Module and check connections for Temp Rheostat or spray Electrical cleaner on it.

4. Purchase new Dash Climate Control Module, Heater Control Servo Motor, and Water Control Valve Cable. And just replace all parts. I’m guessing $250-$300 to do this.

5. Vent Door - I’m not sure where this is- so I’m not sure how to T/S this route.

 

[mtbtim]

There's a guy John that services these 01 & 02 climate control modules for a fair price. It clearly sounds like to me it's having issues and needs repair.

John's contact info in in the video description.

<iframe width="560" height="315" src="https://www.youtube.com/embed/rN0pHmZWTdU" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

 

[jonfasch]

Does he just support the 4Runner Limited Climate Controls? Or also the one with the 3 manual knobs?

Looks like I can buy here for $53.00 - I've never heard of the website though - https://www.evocoolq.top/index.php?...L27P4M1uHFaUhIg2X8Cjo6AfyjFJ7S1VH-CNmRKTkGKnI

 

[mtbtim]

Does he just support the 4Runner Limited Climate Controls? Or also the one with the 3 manual knobs?

Looks like I can buy here for $53.00 - I've never heard of the website though - 01 - 02 Toyota 4Runner Climate Control Assembly Heather A/C Control 55912-35030

John repairs the electronic climate control units in the 01 and 02 models. He doesn't repair the manual versions you find in the 96-00 models as far as I know. But, we list John's contact information in the video description. Contact him and he'll get back to you on what units he services.

 

[jonfasch]

Will do... Just emailed John about it...

I have the manual knobs from 2002 though...

 

[jonfasch]

John gave me some good info... But he said his expertise is on the 4Runner Limited... And not on mine.

Mine isn't the Limited, and has the 3 manual knobs in the picture above.


Current plan is to
1. Verify if I have a seized cable first from Heater Control Servo to the Water Valve in engine compartment - by disconnecting cable on both ends and trying to move it.

2j. Then while cable is disconnected, see if Heater Control Servo lever moves with the turning of the Temp Knob...

This will rule in or out the cable.

and if the cable is good, leave me with the Temp Control Knob/Rheostat or the Control Servo being bad.

I did see a video on how to pull the Control Servo and connect it to a battery and test. That would be my next step.

I plan to do this tonight and tomorrow...

I'll post updates.

 

[jgue467]

It is common for the heater valve in engine compartment to fail, only component to fail twice on my mine. Luck.

 

[jonfasch]

So I dug into it tonight:
1. The GOOD - Verify if cable is seized from Heater Control Servo to the Water Valve in engine compartment - by disconnecting cable on both ends and trying to move it. RESULT - Cable is NOT seized, moves fine.

2. While cable is disconnected, see if Heater Control Servo lever moves with the turning of the Temp Knob... RESULT - Didn't do this, but it wouldn't have moved since cable was good. And something else is bad.

3. The BAD - Took apart the Dash Climate Control Module to spray with Electrical cleaner. DONE... Then did something stupid. I rem'd the flat cable connecting the 2 electrical boards in the Module, could not get it back connected, and messed up the ribbon contacts. So ordered a used module from EBay for $100... Mad at myself about this... As I didn't need to disconnect. But then, I did have problems with this very module a few months ago. It was flaky.

4. The Good - Removed Heater Control Servo Motor (where cable from engine compartment connects). This was easy to get out (3 mounting screws and a cable clamp screw), but will be a bit tougher to get back together. The Servo Motor lever is stuck solid when trying to manually move (but this is correct - don't force it), but I did see a video on how to connect the motor to a battery and test. (https://www.youtube.com/watch?v=yRRcLVNqgC8&fbclid=IwAR2K60hrRLx8cKjPZT1alPSWz5A2DOh46bRvkPsK0SGTEi-3g5YkH_a7B8Y). I did the battery test in the youtube video and it moved as it was supposed to. Now to put it back in tomorrow.

Results to this point.
1. HVAC Blower Control Cable (87286-35040) is good
2. Heater Control Servo Motor (87106-04030) is good.
3. Climate Control Assembly Heater A/C Control (55912-35030) was probably bad (if not, I made it bad).

Now to wait a week plus for my parts to arrive... But I can now put it all back together... as the Climate Control Assy is an easy replace...

 

[jonfasch]

The week has passed… and my used Climate Control Assembly has arrived (see picture).

Easy install at this point – 10 minutes to replace. As I’ve pulled and replaced this too many times the past few weeks.

Did a lot of testing, as I had left the Heater Temperature Control Servo Motor out while I waited for the Control Assembly to arrive. I did test the Servo Motor before I put it back in. There are 4 screws – 3 to hold the servo in and 1 to hold the cable in. Pull up the floor carpet when you do this for easier access with a stubby Phillips. This only took 10 minutes max to reinstall.

All the vents and heat control work great now. All 3 knobs (Fan, Temp, Vent Selection) work as they are supposed to.

Only one issue… and didn’t find it till I went for a night drive. I think the bulbs in the Climate Control Assembly are original… where in mine were the LED’s… the Temp Control and Vent selection are fairly dim… and the Fan Speed is out.

So this weekend, I’ll do one more pull and replace with the bulbs from my old one.