I have a 2013 Civic Coupe EX-L Navi with the Auto Climate Control. I never use the Auto function, just adjust the fan speed. I bought the car in July 2013 and a few weeks later the HVAC fan started making a buzzing or ticking noise. The pitch and frequency would change as you adjust the fan speed. The amount of air coming from the vents did not seem as powerful as my 7th Gen Accord that I previously owned. I took the car back to Honda and they heard the noise and replaced the blower fan (79311-TR0-A01).
It was quiet for a few weeks, then the same noise returned. I couldn't get the car in right away, so I continued to drive it. The AC always blew cold air, but the fan was noisy. As the weeks went by, the fan began to fail. At the highest setting, which is 7 indicator bars on the display, there was not much air coming from the vents. Sometimes it happened immediately, other times it took about 30 minutes of driving before the fan would begin to slow down. It got so bad, there was barely any air coming out of the vents at the highest speed setting.
I took it back to Honda and the fan was barely spinning the moment I started the car. I left the engine running with the AC on and had the service advisor sit in the car to confirm the problem. He confirmed it was not normal operation. Since replacing the blower motor the first time did not solve the problem, they did further research and discovered the fault in the system. The blower resistor/transistor (79330-TS8-A02) was burning out the blower fan. Honda replaced the blower fan and the resistor/transistor to fix the problem. So far, that appears to have fixed the problem. The blower fan blows better than it did when I first bought the car, and it is quiet without any noise but air coming through the vents. I think the resistor/transistor was bad from the very beginning and it burned out the fan, twice.
Here are the service bulletins referenced on my warranty repair invoice:
Blower Motor: 09-097: HVAC Blower motor works only on high speed.
Blower Motor: 11-008: A/C - Blower motor is noisy/reduced blower speed.
Resistor/Transistor: 87-003 - Could not find a TSB on the internet for this one.
I was only able to find a link for the TSB 09-097, which was for the 2009 Fit. The cause was excessive current draw from the blower motor causing the blower resistor to fail. Repair was to replace the blower fan and blower resistor. I found a paid link for 11-008, which had the title "Blower motor is noisy/reduced blower speed." I could not find a website with the TSB to view it. I could not find any listing for 87-003.
So if you are experiencing similar problems with your Civic's HVAC system, the resistor/transistor, which controls the fan speed, might be the problem. Below is a YouTube link with a video demonstrating the problem with the blower fan. Make sure your speakers are on because it is the sound you want to hear, not the visual to see. The fan was on 7 the entire time and you will hear the slow buzzing noise as the fan was barely spinning. You will hear the fan try to spin faster, but then slow down again. The fan will continue to fluctuate while the car idles. At the end of the video, I turned off the HVAC system and turned it back on so you can hear how loud the noise was in a quiet car.
View: http://youtu.be/w6PfG2PX6Fk
I hope this helps others that experienced the same problem.