[screamy]

The repair worked for me too!

This repair worked perfectly for my 2000 Honda Accord (four-door, EX model).

I was uncertain as to whether or not I should perform this repair, because my AC/Heater control panel was not completely dead. It worked intermittently, but occasionally would either A.) not come on at all, B.) the lights would just blink on/off, or C.) it would work normally for a random period of time.

Regardless, I did the soldering job as chronicled by Hybridmojo and everything worked great. As mentioned in other threads, you'll need to use your soldering iron to melt a small channel in the black plastic panel which covers the circuit board, so your wire doesn't get pinched/crushed when you screw the panel back in place.

A heartfelt thanks to Hybridmojo! You saved me hundreds (if not thousands) of dollars!

 

[disallow]

Did the solder fix today on my 99 EX. It didn't work at first, so I resoldered the jumper wire and also applied Mr. V's cardboard spacer trick. Seems to be working! Time will tell. This was one of the little annoying things about this car, but if the A/C will work reliably, that is a huge plus, and I can drive this thing for another 5 years!

 

[lynsey]

i had the same problem, we went to the junk yard and pulled out a unit from the same car. and it works perfectly now. cheap way to fix.

 

[Pedrordz]

Where is this panel at on the car, you can reach me at pedrordz@swbell.net,

 

[Richieboy]

Hybridmojo, you are my hero.

'98 Accord, manual climate control, same exact symptoms.
None of the through holes on my board looked bad. In fact the board looked really clean and solid. But not having a working multimeter at the moment, I figured I would try Hybridmojo's jumper fix, because what do I have to lose?
It worked like a champ!
Thank you, Hybridmojo! You just save me a s***load of time, money, and inconvenience.
I love me some internets.

 

[Pedrordz]

Greetings, well I fixed the 1999 Honda Accord climate control problem with fan no climate control functions by adding the wire but the A/C and recirculating lights not lid but it is functional now.

 

[kooshnedo]

Came here to say thank you to Hybridmojo. I have never soldered in my life so I googled a tutorial and just did this on my 1998 Accord and it worked!!! Thank you for saving me so much money, summer just started and it is HOT! Amazing what you can find on the internet...

 

[thx to hybrmojo]

This worked. Thanks hybridmojo.

 

[antman747]

Thanks for that fix. Just soldered that jumper in and viola! it works awesome fix. thx

 

[-jeffB]

A slightly different experience...

My 1999 Accord LX started showing the symptoms described in this thread earlier this year, and I planned to do the jumper repair, but was procrastinating. I began having a separate issue with my ignition switch (engine cutting out while driving), and fixed that. While I was doing a shakedown drive to test that, I noticed the climate lights blink off and back on for the first time in a while; this time, I figured I was ready to try the fix.

When I went out a few hours later, though, I smelled hot electronics, and found the area around the temperature knob hot to the touch. (This was after the car had been sitting for several hours, with the key out of the ignition.) When I started the car, no lights or switches were working on the panel. I disconnected the battery, dismantled the console, exposed the board, and started troubleshooting.

Long story short: the trace that everybody has been jumping WAS corroded, but the 7805 was apparently toast. There was a dead short from C1's positive lead to the MIDDLE terminal of the 7805, and R1, a power resistor (maybe 1-watt?) just to the right of the temperature control, was roasting (>500 F). There were metal sparkles condensed on the backing panel in the vicinity of R1; it kind of looked like they'd cooked off the solder connections for R1, which looked somewhat grainy and shrunken, but I would have expected that kind of heat to produce extensive damage to the board itself. I didn't see any sign of that.

I installed the jumper, but it didn't affect my board's behavior -- it was apparently too late. I ended up getting a replacement unit (actually the whole console assembly) from a scrapyard, and installing it fixed the problem.

This was a scary failure mode, though. R1 had already started to melt some of the plastics on the panel around the temperature control. If it had gone much longer, it could well have started a fire, with no one near the car to notice. I sure hope the replacement unit doesn't fail in the same way.

 

[Charrua88]

Hi folks,

I had the same problem and took apart the heater control module to see if I could fix it before dropping $300 on a new one-- in fact, mine was fixable with one jumper wire and a soldering iron. Read on...

Here's another dude just making an account to thank hybridmojo, my computer guy next door did the soldering for me, installed that thing up and viola! Like new, so far so good, at the first run it took a few minutes to come on, my guess it was the computer booting up or something after being unplugged, cuz a shut the car off turned it back on and the climate control started instantly, very thankful, my hat is off

Don't know what happened to my last post, but long story short hybridmojo is the man, did that shit and it worked so far so good, thanks, kudos to my dude hybridmojo

 

[KenA]

Hi folks,

I had the same problem and took apart the heater control module to see if I could fix it before dropping $300 on a new one-- in fact, mine was fixable with one jumper wire and a soldering iron. Read on.

Symptoms:
Only the blower motor speed knob worked. None of the vent buttons, A/C button, or the lights work.

Quick solution:
On the underside of the board, just jumper the input (leftmost) leg of the 78dl05 voltage regulator in the middle of the board to the positive leg of capacitor C1. That's it.

Long story:
Since the whole panel went dead all of a sudden, with nothing working, I pried open the module with a small flat head screwdriver, and pulled the knobs off.

I tested the 5v regulator which supplies 5v power using the 12v from the battery. The part is 78dl05 and it is in the middle of the board.
It was not outputting 5v, so I next checked if it was receiving 12v.
Pin 1 Input (12v)
Pin 2 output (5v)
Pin 3 Common (ground)

Pin 1 of the harness is +12v, and the ground pin is in the very middle all by itself. The board was receiving +12v. So that means that there is an open circuit somewhere between the regulator and the connector.

So I traced back from the input leg of the 78dl05 to the connector CN1. The first through hole was covered in greenish blue corrosion. It is located underneath a rubber strip directly below the 78DL05, which is why I didn't spot it immediately. I wouldn't be surprised if this is how most of these boards fail.

The only other thing between the input leg and the connector CN1 is a capacitor, C1. It looked fine (wasn't burst or leaking). I could have attempted to fix the through hole in the board, but it would likely die again, so I decided to just jumped the input leg to the capacitor, which provides a handy place to solder to.

I jumped the positive side of C1 to the input leg of the 78dl05 (left most leg, labeled in+ on the top side of the board) and then plugged it back into the harness, turned the car on, voila, all works fine.

$293 for the part from the Honda dealer and probably $100 more in labor-- you can do it yourself in 15 minutes if you have a soldering iron ($12 from Radioshack) and a couple of screw drivers. Stupid simple.

If you have about 5vdc (4.91vdc) on the output of the 78DL05 voltage regulator and / or you've tried the jumper fix described by hybridmojo and all of your climate control lights are still off, then check the Zener Diode near Resistor R5. The Zener Diode is a surface mount component and if its contacts fatigue over time, they loose electrical contact. An easy check is to push down with your thumb on this Zener Diode while the control unit is still connected. If the climate control lights begin to function, then you know you have to re-solder the Zener Diode contacts. There's a second Zener Diode right next to it which you might want to check as well.
My car is a 2001 Honda Accord rather than a 1999 Accord, but Gary's fix still worked.


This fix was described in the YouTube comments at:

(1999 Accord A/C control flashing)

My sincere appreciation to Gary Buffington for mentioning this fix.

"...Gary Buffington3 years ago

This is an easy fix. This is a known "pattern failure". I am an Automotive Technician. You need to resolder the small resistor # R5 or ZD (zener diode with 3 prongs/legs) that is directly beside the #R5. You need to remove the circuit board as these 2 items are on the inside not the exposed back side under the back cover. I have fixed several and I just fixed mine tonight myself on my 1999 Accord Coupe 4 cylinder. My problem was the ZD (zener diode) beside the small resistor # R5. Easy fix!

 

[300kHonda]

Thanks Hybridmojo,
I had the same problem. I followed the instructions and added in the jumper wire. Now everything works perfectly. I found the same through hole was corroded on my circuit board. Also saw some extra corrosion on the part called CN2.

Before adding the jumper wire i decided to cleaned off the corrosion on the board and test to see if that would fix it. It brought some life back to the board for about 1 minute then it went into failure mode again.

I was concerned about adding the jumper wire and powering up the board. That it could cause more damage if done wrong. Wasn't sure if I could trust your pictures and diagram. But your insight into how the circuit-board worked proved very accurate and valuable. I first did some probing to verify the accuracy your info. I added the jumper wire and tested. Worked great. I would not have been able to do this without your sharing this info. Thanks so much.

Other Insights and recommendations.

I had to cut some space into the black plastic cover plate that goes over the circuit board. That space was needed to accommodate the jumper wire. Else the black plastic cover would not fit evenly or securely hold the circuit board down against the assembly. Because this tight fit is so important, it seems more ideal to put the jumper wire on the opposite side of the board. I didn't do this but I think anyone else who does this fix should. One will just have to find corresponding places to solder the wire on the other side of the board. (Top side of board) So on the top side it would probably be very easy to connect the jumper wire to the input leg of the power regulator (78DL05). The other point to connect the jumper wire has to have electrical continuity with the postive leg of Capacitor C1. No matter if you solder the wire to the front or back of the board, one should have a voltmeter and probe the board’s connection points for accuracy before soldering the jumper wire.

I had issues with the black plastic cover plate which I had to fix. I think all these same issues I had will occur if you don't create space in the black plastic cover plate for the jumper wire. But I did create that space and had issues for other reasons.

Some of the screws that hold that plate down broke the plastic threading that they screw into. This could be my fault for over-tightening. But i suspect it also had to do with the angle the assembly was laying on the table. I didn’t brace it properly at first. I believe that one should not let the assembly lay down in a way that the control knob is directly against the workbench or table. That is what I did at first and probably caused the screw threadings to break.

The result was a relatively loose fit of the circuit board into the assembly. Because of the loose fit, some of the buttons did not work. You will find that the black plate, and circuit board underneath, must make firm contact with the control panel assembly. If not then pushing a button on the assembly panel won't result in contact with the corresponding button on the board. The button won’t activate and light up when you push it.

To fix this I had to create a more firm and tight fit of the black plastic cover plate onto the assembly. I ended up applying pressure with my hand and adding duct tape to hold that pressure. It held ok. So all the buttons worked.

For those who are going to try this fix, i would be extra cautious about how you lay the assembly down when tightening or un-tightening the screws. Don't let the control knob rest directly on your workbench. Support the entire assembly with towels or hold it at an angle so the control knob does not bear any weight. Also, when tightening I found it is better to apply pressure on the black plastic case with one hand, and slowly tighten a screw with the other hand to the point that the screw will maintain the pressure you applied with your hand.

 

[Non Quixote]

Worked for me

I did the jumper fix on my climate control several years ago and it continued working right up until last year when the rheostat started to flake out and not work unless I shoved a penny under the knob. Replaced the "jumpered" climate control with one I found on EBay, but am happy to have gotten years out of the old one with the simple fix!

 

[mrdigital]

I took out my panel today and followed hybridmojo's guide. I found out that in order for mine to work, there had to be a certain spot on the circuit board pressed down. I put a couple layers of cardboard onto the backplate and used masking tape to secure it so when I installed it back on, it would press the area of a circuit board for it to work.

My LEDs would come on and off whenever they liked, and a week ago just went completely dead. Now, I'm not sure if it was because I followed hybridmojo's guide or just simply because of that cardboard I added to put pressure on the circuit board. Sadly I didn't take any pictures of my project, but I'll use hybridmojo's picture to demonstrate.

Here is where the area where pressure was needed. As I said before, I just taped cardboard to the back plate where the area of pressure was needed and installed everything back. Works like it should. Wish I would have done this sooner.

Can you share the picture showing the area where pressure is needed? Thanks.

 

[Diaballa33]

First post ever on here.

Came here to say thank you to Hybridmojo. To those who may try this it took me a few minutes after unscrewing the 3 main screws to remove the assembly from the dash to get it removed. I pulled the top portion halfway off then at the bottom there is one clip that holds everything together. Depressing that clip makes things much easier. As far as making room for the jumper I actually didn't. Instead I snaked the jumper around a few of the four steeple connectors just below the solder spot thats not D3.

I have never soldered in my life so of course I had to youtube a couple videos and buy a$17 soldering Iron from Radio Shack, then the actual solder from HOme Depot. Just buy everything from home depot, lesson learned there. Next to the welding supplies near the front of the store.

Hopefully this fix lasts as I'd like to avoid having a car payment till after summer's over if I can help it!

THANK YOU AGAIN HYBRIDMOJO! There's also a great video by IRON TANKER on youtube that references H's post if there's still confusion.

 

[greybeardmike]

Thanks Hybridmojo

Thanks Hybridmojo. The fix worked fine for me. Saved me a lot of trouble. Thanks again.

 

[JamieRI]

Galvanic corrosion killed the via

The root cause of this issue is galvanic corrosion: a noise-damping gasket in the plastic housing runs directly over an exposed via in the 12v trace leading to the voltage regulator. Even one event of moisture (windows left open with condensing humidity) will cause rapid corrosion on the positive (anode) node when a DC potential with electrolyte (the water) is present. In this case, the anode is the via that everyone finds is corroded, including me. I took pictures of this when I soldered the wire.

I removed the two gaskets when I reassembled the control panel.

I cut mouse bites in the black plastic and ran the wire outside of the housing.

 

[datechbpss101]

I have been waiting for a brand new control unit from Honda, CHH has been telling me that it is going to be available end of August. So I placed an order and few days later, I get a call from them saying its on back order from Honda until October. As of right now, the original control unit in my car works intermittently, with the Head only mode, A/C and rear defrost working, and while blowing ice cold a/c. Root of cause might be outside heat and humidity, especially in Florida.

 

[NBE1]

I was lucky enough to find one at a pick n pull for 11 dollars. Works great