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I have a 2003 Civic. It had overheated 3 times. Finally Replaced the engine with a fresh one. I notice after the last overheating session that the ac is not working. I have read many of these forums and no one has had the same exact problem as I have.

So here is what I know

Start the car A/C light is on in the dash.

• Condenser fan(s) are not working
• Compressor Clutch, not engaging.

These are some of the other factors I know for sure

• freon levels are exact
• brand new compressor
• relays were tested with a power probe
• all fuses are good
• power probe is able to engage clutch and fans

I can turn on the fans, engage the clutch using the power problem. I also tested the coolant sensor and it too is good.

when I remove the relays and measure for triggering signal coming to the fuse/relay box I am getting nothing.

since the horn is there we looked for the signal and found it and then attempted to locate signals for the compressor, fans etc

Can someone guide me to a step by step to locate this problem? All Fuses and Relays are tested.

does anyone have a diagram? HELP!! I have to get this car running asap. do not want to have an overheating problem again.

HOT FLORIDA SUN!

 
Rep Power: 119

That is because your mixing together 2 separate issues.

Hook a advanced diagnostic computer up to your car and monitor to see if the PCM is attempting to send a signal to the AC relays.

If it is, backprobe the pin and see if it is working, if it is look for a break in the wire going to the relay.

If it’s not then your concerned with ac control switch and micu working correctly.

Put aside your thoughts this is caused by your over heating, it’s a A/C problem only.

 
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At the ECM/PCM with the A/C enabled in the HVAC controls you should have ground at pin B6 (fan control, green wire) and E18 (compressor clutch, red wire).

 
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Now I lost the light at the temp control. I ran a self-test. I got no codes and then it went black.

 
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Possibly HVAC control unit malfunctioning? Does the mode, temperature, and fan controls work?

 
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It did yesterday, ran the self-test and had no problems. Now I have no lights coming on the temp control unit. at all checked all fuses. completely lost now. SMH

 
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Does anyone have a Diagram for this ?

 
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It is in the service manual which can be found here: https://www.civicforums.com/forums/1...pdated-10.html

 
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ok thanks, I will need it. Not sure why this continues to get worse. snapon Apolo scanner said ecu doesn't support test. so i am hunting it this way.

 
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There is symptom based troubleshooting in the service manual, page 21-68. Following the "A/C System does not come on (both fans and compressor)" it recommends checking the A/C pressure switch circuit, page 21-78.

 
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I have no light on the controller now. not sure what's happening I am so ready for a huge bonfire.

 
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What do you mean no light on the controller (backlight or A/C button)? Does the A/C button light come on when pressed? Does the mode, temperature, and fan controls work?

 
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It was working. and even ran a good test. Now we have no lights no fan etc. the HVAC are dead.

 
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Check the under-hood fuse number 14 (10A).

 
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#14 under the hood show 40 amp "option"

 
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it is a 2003 Civic EX coupe

 
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I GOT IT #14 under the dash.


ok i got the light back on in the temp control. ran a test and no errors.

relays under the hood are not clicking and the fans do not turn on when ac is pushed. now what?

update: found the pages you mentioned will try the step by step procedures

 
Rep Power: 224

Sorry about that, sometimes I don't know how to read.

As you mentioned the next step is to check the A/C pressure switch. If the system pressure is too high or the switch is bad the compressor and fans will not engage.

 
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ok, i will just recover it and replace it.

 
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Do you have gauges for the high and low side? What do they read?

The A/C pressure switch is happy between 28-455 psi. If you're in that range the pressure switch may be bad. Follow the steps to test it.

 
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I’m not getting any lights on the control panel, I turn the fan **** and it doesn’t kick on either. I’ve checked the fuses and relays, they seem fine what else could be the problem?

 
Rep Power: 224

Does everything else work?

Check fuse 14 (10 amp) in the under-dash box. Like, actually check it with a meter.

 
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Fuse #14 (7.5A) also protects the remote mirrors - if they don't work then sure sign this fuse is your problem.