Fixing Toyota Highlander AC/Heat Issue

My (ex)wife had a 2004 Toyota Highlander that was exhibiting some strange issues with the A/C and heat. In the summer while driving with the A/C on it would randomly just switch to heat and just as randomly switch back later. Sometimes bumps would trigger it or a sharp turn. Same would occur in the winter while using the heat. It would randomly switch to A/C and back.

The problem was pretty annoying but I suspect fearing the possible cost to repair kept her from bringing it in for service.

The issue seemed to get worse over time and with the horrible Louisiana summer heat and humidity quickly approaching she finally brought it in to get inspected and to get a quote.

The shop she brought it to “checked it” and told her it was the “temperature control actuator”. They told her it would cost about $500 to fix.

After getting this information I went to Autozone and O’Reilly’s trying to find this part and what it costs. Neither could find this part. This made me pretty curious and wondered why no one could identify the part. So I went sit in my car and whipped out the iPhone to Google this part and figure out what was going on. I didn’t find any mention of a “temperature control actuator” for a Toyota Highlander but I did find lots of information pointing to what appeared to be the same A/C issue with the Highlander by many people.

I found many complaining that they had to replace the A/C control assembly to fix the problem. The A/C control assembly sells between $700 – $1000, just depends on where you get it. Labor to replace it was between $300-$500. Many reported paying or getting quotes between $1200 – $1500 to replace it.

This was not looking good. I went back inside the store and confirmed the part was $700+ but they didn’t have it. Turns out this was a good thing. It caused me to go back to the car and start searching for that part. This time, I stumbled across someone who was a mechanic who ran across this problem with a client. He mentioned that after he took everything apart thinking he was going to have to replace the A/C control assembly he found the real problem. Apparently the issue is with the temperature control switch (knob) and the three wires connecting it to the control assembly circuit board had broken. This was especially interesting because it really seemed like it made more sense to me. The fact that bumps in the road would cause this to work and not work really made me think this was a short or something along those lines. I didn’t buy the other explanations personally because most of them would have only accounted for it not working entirely and not sporadically.

So…. I decided this broken wire issue had to be the problem and I would at least check this out before spending any money. Figured I didn’t have anything to lose by confirming this.

I went home and went straight at it. Tore the center console apart and got to the control panel. Tore the control panel apart and got to the circuit board (control assembly). Sure enough two of the three wires connecting the temperature control to the circuit board had broken off.

Yay! Got it soldered again and everything reassembled and sure enough, it is working like a champ and cost NOTHING to fix it! Sad that most places wouldn’t attempt to solder it back but rather would just charge people $1500 to replace the whole control assembly.

Anyway… with all that said I thought I would share and detail the process for others in the hopes of saving others a ton of money in the future.

***Couple of New Notes – Please Read***

I highly recommend doing as others have suggested and replacing the ribbon cable you need to solder back together. Part of the problem with the current design seems to be that the ribbon cable is too short. This causes added tension when things are put together and adds to the issue with the wire breaking.

Also, you will or should know how to clean the old solder from the holes on the circuit board in order to correctly solder things back together. Use a desoldering pump to assist with this. If you don’t know how to solder you might be able to find a small local computer repair shop or trade school with people willing to do it for very cheap.

Appreciate all the great feedback this post has been getting, makes you feel good to hear the positive comments.

***End Notes***

5/30/2011 – Just slightly over a year since I put this post up and I think we have easily helped over 100 people either DIY or with slight help (soldering isn’t for everyone, thank God for computer or TV repair shops). At an average of $800 to have someone replace this board or Toyota to fix it well it looks like we have saved about $80,000 total. I know that number is on the short side too. Maybe I should get into the Highlander AC repair business. 🙂

Hope everyone continues to find success with this and please continue to share your success here. It’s a great feeling to get to read all these comments!
***End Update***












Step 1. Remove the knobs. These simply pull right off.



Step 2. Remove the trim panel from the center console. Start at the bottom on one side and then the other. Work your way to the top. This is easily done with no tools and just a little force.







Step 3. There are six 10mm bolts to remove that are holding the center console in place. (Three on each side of console)



Step 4. Remove two screws from both sides of the assembly.



Step 5. Pry the bracket away from the control assembly in order to clear the alignment pins.






Step 6. Unplug the wiring from the control assembly. There are three things to unplug.






Step 7. You should now have the control assembly module completely removed from the console. In order to access the circuit board inside the black plastic housing of the control assembly, you will need to remove the screws holding the rear plastic cover on. Once the screws are removed you can separate the two pieces slowly. You can only separate it slightly as there is a ribbon cable connecting one circuit board to the other.

I pried one side (where the cable was) apart and then used a butter knife to release the connector for the ribbon cable. Once the cable is free you can completely separate the two pieces.





Step 8. Remove the screws and clips holding the circuit board in place.



Step 9. Remove the nuts that hold the switches in place.



Step 10. With the circuit boards and switches removed from the assembly, I could now see the real problem. Two of the three wires that connect the switch to the circuit board were broken. Clean away the old solder and wire pieces. You should have three clean holes on the switch board in which to re-solder the wires to. I’m no expert on soldering but it wasn’t hard at all. If you’re not comfortable soldering something such as this then find someone who is.







Once things are soldered back together you basically need to reverse this entire process to reassemble everything. It really was pretty quick and easy to do and it can likely save you lots of money.

Good luck!

138 Responses

Leave a Reply

%d bloggers like this: