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I have searched but could not find an answer. I have a 2001 sedan the ac just went out. The ac was working fine last night now it blows outside temps. The fans don't come on and neither does the compressor. I know a little about ac this is what I have done. I checked the fuses and relays good. Checked the freon has good pressure. I can jump pins 2 and 4 on compressor relay and the condenser fan relay and fan will come on. I jumped 2 and 1 on the relay and the compressor came on but the car idled low and ruff. So I jumped 4 to 2 and 2 to 1 and the fan came on and the compressor came on but car ran low and ruff. I jumped the I guess low switch the one on accumulator nothing. I ran a jumper to the compressor and got low and ruff idle. There was no unusual sounds like a compressor or belt. Any ideas ?

 
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And also now the power door locks don't work.

 
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well the car running low and rough may mean a problem with the compressor where it is overbearing and bogging the engine down. At least that makes sense to me.

Maybe try replacing the relay and hope it works? Its pretty cheap for a relay.

 
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I have the same problem with my car 02 EX coupe, a mechanic told me it could be the computer, I'm searching for an answer to this problem.

bigmacnfrys do you find the problem

 
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did your door locks stop working? This happened at the same time as the a/c.

 
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I was thinking the Multiplex Control Unit maybe. Door locks stopped working and a/c and the e-brake light is on. All happened at the same time. Anybody got an idea?

 
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Yes at the same time. This sucks

 
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check this link it has god info to troubleshot this issue

http://en.allexperts.com/q/Auto-Air-...da-Civic-1.htm

 
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I have been told the multiplex control unit is in the fuse box. Is it the one in the car or under the hood? And if I change the fuse box will that work?

 
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I change mine and works, you have to by the fuse box that's in the car the multiplex in built on it. I buy mine from

http://www.hondaautomotiveparts.com)

System\Component : CONTROL UNIT (CABIN) Item # 5

I also buy the 3 relays, Item # 9

 
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Hey. I've been having a similar problem since last year. I have an '03 Civic LX (in Canada). And the little green light for the AC unit comes on, but the compressor, etc. never turns on. And occasionally, especially when the weather is warm, I lose *all* electrical power temporarily: the radio goes off, all of the console lights are off. And I think from what happened last summer, I even lose power brakes (or was it power steering?). This power loss hasn't happened all winter, but twice this weekend, I lost power to the radio, console, etc.: once while coming to a stop at a light at an off ramp, and once when I was just parking.

So does having a faulty MCU/Fuse Box explain this problem? My mechanic seems to think that it might be the ECM, but he says that it has to be done at the dealership since the immobilizer has to be reprogrammed and he can't do it. And the dealer is quoting $1500+ to change and reprogram the immobilizer and my keys.

So any thoughts before I fix this?

Thanks!

 
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Here is the Multiplex Control System System Description:

The system controls the function of these circuits:

* Entry light control
* Wiper/washer (including intermittent wiper)
* Interlock
* Keyless/power Door Lock
* Key - in reminder

Check out the online manual:

http://justmycar.moxiereporting.com/HondaManual/

One mechanic told me the same that it might be the ECM. After searching the internet I found this website http://www.justanswer.com/ you can chat with certified honda tech and the fee is 9 dollars. All the answers I got from different people point to the Multiplex.

give it a try, the cost is 124 compare to 1500

 
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I think I found it. I changed the fuse box and all seems to be working good. I had some issues from ebay so after some wrong ones and some 3 weeks later I ended up with 3 fuse boxes. But it seems to fixed it. I think is was the multiplex control unit that is in the fuse box. I looked at all the wiring diagram's and it all made since. All the grounds for the issues I had went to the Multiplex unit. Best bet is the link above at honda parts its around 150$ shipped And you won't have to deal with ebay. Dealer is 136.00 or 160. at customer cost if they even have it (my dealer didn't) My car the a/c, door locks,Key - in reminder,intermittent wiper Did not work and the ebrake light stayed on. Hope this helps the next person.

 
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My wife's 2001 Civic had the symptoms described above. All at once, the following quit working:

1) All key fob functions (remote lock/unlock and panic button).
2) Intermittent wiper;
3) Power door locks (doors could only be locked with the key);
4) "Courtesy" entry light;
5) Warning chimes for key-in-ignition and headlights on;

Also, the brake light stayed on.

Replacing the MCU, as suggested above, fixed the problem. I ordered the part from the same place as HiVtec:

http://www.hondaautomotiveparts.com (System\Component : CONTROL UNIT (CABIN) Item # 5)

It took about an hour to replace. An easy job, other than trying to release the various plugs while lying on your back with limited space to work in (my fingers started to cramp up after awhile). For the most part, I transferred plugs from old to new one at a time, even though most (if not all?) of the plugs are unique, such that they can't be reinstalled in the wrong receptacle.

The last thing I did was transfer over the four relays. Interestingly, the fuse box comes will all the fuses pre-installed, so there's no need to transfer fuses.

The fuse box slides into a track and is held in place by a single (IIRC) #10 hex head screw.

Have your radio code handy, as removing the fuse box will disconnect power to the radio.

 
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I have an 01 Civic EX - same problem as other posts happened Today ironically, Dome light does not light while door is Open, Power locks don't respond to remote or door switch, A/C does not cool, and Brake light stays lit on dash.....

All forums/threads point to MCU under steering column,
Honda Part**** 38200-S5A-A31, about $150 bucks online from Honda parts now. Will let you know what happens when I replace it.

Honda Part**** 38200-S5A-A31, Fuse Assy.

 
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Hi You guys, do you have electrical diagram for A/C switch button NH-365L? is a 9 pin harness but i don't know whero cables have to be installed. Thanks