I have a 99 Accord LX. The Heater / AC Control buttons will not light up.
The fan blower works fine. The air conditioning will not come on.
The rear windshield defroster will not come on.
I have taken off the bezel and reseated the connections with no luck.
I have also checked all the fuses with no luck.
I swapped the relays in the engine compartment fuse box for the condensing fan
with the ones for the lighting system. No difference, so it seems that the relays are okay.
From what I can tell I need to replace the Heater / AC control. I do not have Climate Control.
On ebay I have only been able to find Heater / AC controls that have climate control.
Is my car capable of using the Heater / AC control that has climate control?
If yes, will the climate control work?
Or are there some missing components to the system.

The heater control panel is computer controlled and has a self diagnostic function. If you have access to a Honda service manual it gives all the details. If not I believe you turn the ignition ON, Fan OFF and Recirculation switch ON. Push and hold the Recirculation button (light goes OFF) until the Recirculation light starts blinking out codes (long and short blinks). Dont ask me how to read them. You will probably have to see a dealer for that.
There are fuses under the hood #54 & #56 and in the drivers side panel #3 and passenger side panel #13. A bad ground could also be a cause.
I doubt a climate control panel will work on a standard panel car, but I really don't know.

Good Luck

HunterX:

As in your '99, I have the same "Manual" HVAC controls in my '02. They are NOT interchangeable with the "Automatic" climate control system components used in the "EX" cars. And vice-versa.

Sounds like you've done all your basic homework very well. I suspect a faulty control unit, with several of your switches being defective. I am ASSUMING there is nothing otherwise wrong with your A/C system and your RW defroster.

If you can't find an ostensibly decent used one in a local salvage yard, you may have to bite the bullet for a new one from your dealer. At Majestic Honda's website, they indicate a price of $162.70. Plug in your VIN, then look under "heater controls" for the exploded diagram and cost.

http://www.hondaautomotiveparts.com/

Thanks for the information.
I now know that the "Manual" and "Auto" AC controls are not interchangeable.
Does anyone have a wiring diagram for the Heater / AC control?
Wondering if I can jumper some wires together to see if the air conditioning will come on.
There are two harnesses on the back I figure one controls the fan blower and the other controls the temperature and control buttons.

HunterX:

I strongly advise against what you are considering. Toast the wiring harnesses (and likely other electrical components) and you'll be crying some big elephant tears. (Read, ultra EXPENSIVE repairs!)

If you so care to persist, get your dealer to copy it out of the factory service manual or print it off the Honda Techline.

Sniff, sniff. Where's my fire extinguisher? I smell SMOKE.

Update:
Bought a replacement AC / Heater Control off of ebay.
Everything has been working for a about a week.
So, I guess my original AC / Heater Control was bad.

Thanks to everyone.

Update:
Bought a replacement AC / Heater Control off of ebay.
Everything has been working for a about a week.
So, I guess my original AC / Heater Control was bad.

Thanks to everyone.

I have the same problem on my Accord LX 1999. Looks like I need to buy and install a new AC / Heater Control. Could you please share the instructions for swapping this component. Thanks.

I have the same problem on my Accord LX 1999. Looks like I need to buy and install a new AC / Heater Control. Could you please share the instructions for swapping this component. Thanks.

I just fixed a 2000 Accord LX with this snafu. The good news is that this is as close to plug and play for a fix as you can get.

You can look up how to access the radio for detailed directions but in a nutshell:
- Remove plastic shroud/surround in center of dash
*remove 2 screws at bottom
*FOr third scres, it's hidden behind the clock. Using a thin bladed knife (I used a kitchen knife wrapped in a paper ticcue to avoid scratshing) or screwdriver, pry the bottom of the clock out and pull the unit out. Unplug the wires and set aside. Take out 3rd screw behind in dash. Lift shroud from bottom out.
- AC control unit is mounted to the back of the shroud.
*Disconnect the 2 wiring harnesses from AC control unit.
*Remove the 5 mounting screws and remove AC unit panel.
*Before mounting new unit, lug in the 2 wiring harnesses and check operation...you should be good to go if the original part was the failure.
- Replace pieces in reverse order

Easy-Peasy...be careful and patient with those plastic pieces so you don't scratch them.

I am having the same problem as HunterX and Markov314, with a twist. I have the control exposed and ready to replace and the 2 harnesses disconnected, soon as i buy one, but my compressor is turning on and off without the control being connected. Any thoughts?

i have 1999 accord ex 4 cyl . heat control is work only high speed (4), 1 2 3 it does work. any body know this problem? please help me. thank you.

My father has a 2002 Ford focus that he had that problem with (The fan only working on 4) It ended up being a relay i believe. I don't know which one but i assume one of the relays for the heater or the fan.

did you ever get this resolved? I have a 99 V6 coupe and the only thing that always works it the fan speed. The A/C only comes on intermittently and I get lucky if I can get it to switch from cool to hot air. Sometimes the lights come on but once they go off, the only thing that works is the last setting it was on and the fan speed.

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.

I just fixed a 2000 Accord LX with this snafu. The good news is that this is as close to plug and play for a fix as you can get.

You can look up how to access the radio for detailed directions but in a nutshell:
- Remove plastic shroud/surround in center of dash
*remove 2 screws at bottom
*FOr third scres, it's hidden behind the clock. Using a thin bladed knife (I used a kitchen knife wrapped in a paper ticcue to avoid scratshing) or screwdriver, pry the bottom of the clock out and pull the unit out. Unplug the wires and set aside. Take out 3rd screw behind in dash. Lift shroud from bottom out.
- AC control unit is mounted to the back of the shroud.
*Disconnect the 2 wiring harnesses from AC control unit.
*Remove the 5 mounting screws and remove AC unit panel.
*Before mounting new unit, lug in the 2 wiring harnesses and check operation...you should be good to go if the original part was the failure.
- Replace pieces in reverse order

Easy-Peasy...be careful and patient with those plastic pieces so you don't scratch them.

Just curious, my control works just fine, but sometimes the backlight for the temperature control won't come on after starting the car, and sometimes it's the backlight behind the 3 bottom buttons (recirc, A/C/, and rear defrost). The LEDs for the buttons still work, and the function of the temperature dial still works, just the lights won't come on. However, a light knock on the right side of the the dashboard, just to the left of the glovebox, will bring the lights back on. Is this a related thing? It never really bothered me much since all it took was a knock next to the control to get it to come back on, and even if it was off, the control still functions.

Thank you, hybridmojo! Brilliant fix.

I pulled my panel out and started looking at it. I have quite a few other bad throughholes from the top rubber piece. That might explain why my LEDs have either been going out, or sometimes stay on very faintly even when the key isn't in the ignition. I'm not sure it's worth trying to fix those. A lot of the bad through holes are right next to the microchip on the board. Any idea what that chip controls? If I had to guess, it's what sends the signals to the climate control system to change the temperature, the vents and light up the correct panel light. It's really hard for me to figure out what tracings go where with some of the corrosion to the surface of the PCB. Sigh.

All the same, I'm going to attempt your fix. I also have corrosion on that same through hole you did, and I'll see what happens.

[UPDATE]:
So I did the soldering, and attempted to scrape off some of the corrosion that existed in other spots. I think that was a pretty dumb move. Now the blower speed light doesn't work, nor do any of the backlights for the buttons--but the LEDs still work! I don't get it. Also, the temp control light still works.

I'm not sure if my scratching at the corrosion caused it, or if just handling the board caused the lights to break.

Regardless, I'm still testing the panel. The problem is that it's not something that happens every time I use the car. Sometimes it works for days... others it's broken for weeks. Sometimes it flickers constantly. We'll see, but so far it's SOLID.

Thank Hybridmojo, I am new to the boards here but I pulled my unit out and did the repair as instructed by the description and pics and my 99 Accord LX works perfect. Thanks save me a bunch of money on a new one.

I just fixed a 2000 Accord LX with this snafu. The good news is that this is as close to plug and play for a fix as you can get.

You can look up how to access the radio for detailed directions but in a nutshell:
- Remove plastic shroud/surround in center of dash
*remove 2 screws at bottom
*FOr third scres, it's hidden behind the clock. Using a thin bladed knife (I used a kitchen knife wrapped in a paper ticcue to avoid scratshing) or screwdriver, pry the bottom of the clock out and pull the unit out. Unplug the wires and set aside. Take out 3rd screw behind in dash. Lift shroud from bottom out.
- AC control unit is mounted to the back of the shroud.
*Disconnect the 2 wiring harnesses from AC control unit.
*Remove the 5 mounting screws and remove AC unit panel.
*Before mounting new unit, lug in the 2 wiring harnesses and check operation...you should be good to go if the original part was the failure.
- Replace pieces in reverse order

Easy-Peasy...be careful and patient with those plastic pieces so you don't scratch them.
I want to remove the same part inorder to troubleshoot/replace-if-necessary the A/C Ctrol Unit. I am not to ggod working with those plastic parts. Is there any hidden plastic clip or any special trick that I need to be aware of, other than the thre screws that need to be removed?

Hi,
I have a 98 accord 4dr LX. in 205 i replaced my original climate control with a one I've at the junkyard, it lasted 4 years, The in 2009 i did it again - replaced the unit with a used one from a junkyard. Now that one broke too.. So now i have 3 broken units so, when I found your post I did what you recommended to 2 of the units, both worked for about 1 day and now are again inoperable. I am sure I connected the jumper wire to the correct places shown. As a note one of the units did have the burned mar in the exact place you show but the second one didnt'. Anyway, I am still looking for a solution but looks like I'm going back to the junkyard for the 4th climate control unit, good thing is they cost only $30 a pop. And if there is anything else that I can do to these boards to fix them please let me know, and thanks for all the informative posts everyone, Konrad.

did you ever get this resolved? I have a 99 V6 coupe and the only thing that always works it the fan speed. The A/C only comes on intermittently and I get lucky if I can get it to switch from cool to hot air. Sometimes the lights come on but once they go off, the only thing that works is the last setting it was on and the fan speed.

that's the same exact problem I'm having.. You even get it fixed?? ****s in the winter cuz half the time it's stuck on cold air on the highway in the winter.. Any solution besides replacing the damn thing??

Just fixed mine, same symptoms.
Fan blows but non of the buttons react and no leds
once the board was out of the housing it works just fine and all checks out, however when installed back..same thing, finally I figured (by trial and error) that its the plastic back cover! installed it without it (using the same screws)
and it works just fine.....crazy? maybe, but it works!

I have a 2000 honda accord coupe that came from the factory w/o the climate control on the dash, but will it work if I installed the climate control bezel myself? Like if I got the dash bezel from the same type of honda with the climate control?

Did the repair, it works fine.
- A flat bladed screwdriver slid in the two clips at the top help the ac/radio facia come off easy.

- There are seven small gold screws to remove the back of the computer. Leave the five black ones in.

- A point tip might be easier than a spade tip on the soldering iron, especially if you are not real comfortable with soldering.

- Prep the wire and cut it down as short as your soldering skill will allow. Think about the routing to avoid shorting the repair. I routed the jumper from the 78dl05 in the opposite direction because there was less things to short out on. Then I soldered my jumper to the top of the connection.

- When assembling, be careful that all parts are fitting. The LEDs bend back, but the switches don't bend nicely. I repaired the recirc switch, rebending the contacts after pulling the switch and the plunger out.

hybridmojo, Thanks for taking the time to prepare such a detailed instruction on the C1 > 78dl05 jumper!! I experienced the same failure and your instruction allowed me to attempt (& suceed) in a repair that, otherwise, I would never have attempted. GREAT CONTRIBUTION!

Regards, Jim

This fix works! My A/C used to work 95% of the time and would cut out periodically. I took my car into the dealership a couple times to fix this but of course the A/C would work while they were looking at it. They would just replace my freon or something, take my money, and get me out of there.

One day my A/C finally started going out consistently and I found this post. Exact same problem, there was a greenish blue corroded via underneath the rubber strip on the circuit board. Soldering a wire around this was a quick repair and has saved me a ton of money. Thanks for figuring this out and posting it!!!

Wow. The soldering worked for me. A/C lights started flashing/blinking a few weeks ago during which no cold air would blow (Florida + Summer = No Bueno). It would only be occasional and usually would come back on during the drive. It progressively got worse until a few days ago it was permanent (and the lights were REALLY dim while flashing to almost out completely). Found this forum and thought I'd give it a try. I had previously never used a solder gun. Sure enough the lights are back on and cold air blowing. One of the A/C lights isnt coming on, but the button is working... so be careful when handling the circuit board/lights. Dont forget to cut some of the plastic around where the wire will be traveling (on the plastic backing you unscrew to get to the circuit board), because it wont fit on properly if you dont. HYBRIDMOJO is the MAN!

I didnt see any corrosion on my circuit board though. So that is probably not the issue, just the circuit board going bad after 13 years. Hondas are the SHIT!

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.

...

$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.

This worked superbly for me as well. Thanks a ton, Mr. Mojo. Your post is part of what makes the internet such a terrific resource!

[My problem was the same intermittent blinking non-function of the AC controls that led most of us to this page on a 2000 Accord EX sedan.]

I registered with the forum just to tip my hat to hybridmojo for the excellent repair procedure. My climate control had become iffy lately, sometimes working, sometimes not. Finally the panel went dead and stayed that way.

Found this thread, soldered on my jumper wire and my climate control runs perfectly now. Too bad I found your post after spending $268 on a new CC from the dealer. Oh well, hopefully I can sell it off on eBay for most of my money back!

Thanks again!

Couldn't see how to edit my previous post, but just wanted to say that I was able to return the new CC that I had bought from the dealer (my local Honda dealer is da bomb!) for a full refund. You just saved me $268 Mojo, many thanks!

Repair still working perfectly.

Thanks hybridmojo for the link, worked great. Oh and one tip is check the board and clean it up i had corrosion build and a broken solder on a resister. redid solder on the resister and cleaned up the board plugged it up and boom ice cold a/c. :) it is crazy how this is a common problem but no recall. Oh and this is my first post. Just join the forum because of a great information there is.

ya know... i have the same problem with my 98 accord ex.... no lights but air will blow, but i just punch my relay thing and it all starts working again... caveman solution, but it always works...

caveman solution, but it always works...

Not caveman. Think the way things used to be before the world became throw away. :thmsup:

I just did this today after a year of my wife beating on the dash!!!! Works perfect!!!! Thank you!!!!!

Finally took the time to do the solder fix....THANKS HYBRIDMOJO

:banana:


I didnt do such a good job....crappy solder skills....
had problems putting back the back plate because the back plate wont accomodate the wire//had to force the screws to go in...
asides from that I thought I had to change the compressor...the lights were not totally out...they were intermittent....especially the past 2 years....so Im glad I can get by...and its cool on demand...

My only prob now is that there is so much belt squeal...even after changing the belt and tightening it...Im starting to believe that its the compressor clutch bearing...interwebz is awesome!

btw...I didnt suffer from corrosion or anything like that....it was just intermittent...and mostly noticed in SUMMER when I NEED THE AC MOST!!!!!!

4 cyl 2.3l 01' EX coupe

I have a 2000 Accord EX that is exhibiting the exact same symptoms. The LEDs come on intermittently and the controls (buttons and temp knob) only operate when the LEDs are on.

I found this thread and read through the entire thing thinking that this was the solution. Thanks to hybridmojo and Bowzer for the information.

I tested the circuit board and the 78DL05 regulator is receiving 12V from the car wire harness. I checked the grounds which were also good. The output of the regulator is also providing 5V. I checked continuity between the input leg of the regulator to the through hole to the capacitor to the CN1 connector all which tested good. I looked all over the board and didn't notice anything that looked burned or corroded.

Based on this it doesn't seem like adding the jumper wire would do anything. Do you guys have any other ideas, or should I just try the jumper anyway?

Thanks in advance.

^^^ I sprayed electric cleaner/degreaser on the cable terminals on the thermostat side....so far so good...although every now and then it will go out I just BANG on it and it turns back on...weird...I guess the solder solution didnt work for me...

its only been a couple days so I will update if it really was successful...but compared to before the light is ON now ...plus I can just bang on the panel and it will light up...also its on whenever I start the car unlike before it was pretty random...

random > on my way home it never turns on OR its off then midway to work or home it starts blinking back up...

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.

http://img845.imageshack.us/img845/2584/accordp.png