Hello

My 2004 Honda Civic hybrid has an A/C issue. After I start the car I turn on the A/C at which point you can hear the compressor turn on. This lasts only about 3 seconds then it shuts down...no air in the vents. I can then turn on/off the A/C control and nothing will happen. If I then turn the car off and then on again I can turn on the A/C, it lasts three or four seconds and shuts off again. Rinse and repeat.

Any thoughts on why or what I can check would be appreciated.

Thanks

jom

 

No air at the vents? Have you looked to see if the compressor is on when there is no air at the vents?

 

Thanks

For the (very few) seconds I can hear the compressor is on there isn't any air. However, it does usually take a few seconds to fell any response but in my case the compressor switches off before it has much of a chance.

But....now that you bring it up:

1) I'm not an expert here...I'm just trying to figure out what might be the problem. So when I say it's the compressor I hear I'm really only guessing. But whatever it is that is the sound I'm used to hearing when I turn on the switch...I'm pretty sure it's the compressor.

2) Good point about the air though. I had not checked the situation with the A/C button off. So I did so and get NO air at all out the vents. So maybe I'm wrong and this isn't an A/C issue at all.

If it's not A/C but just no air blowing...what could this be?

Your response helped a great deal...

jom

 

A few year back something similar happened to me. There was no air out the vents. Did some searching on the line and found that the blower heater transistor going bad was a common issue. I found some instructions from the manual that showed me how to test with a multimeter. It was bad. Replaced it and it's been working ever since.

 

Well this could be good news. I'm not a mechanic or an expert at all on these things. However, I'm an electrical engineer and I know what a power transistor is and how to check it.

So..my question now is:

1) What manual are you referring to? The owner manual? If so, I got that but somehow I doubt there is anything in there about this transistor...I'll check though.

2) Lacking that...where can I find the location of this transistor?

Thanks for all of the help!

jom

 

This is how to test it.
Part 1 -How to Test the Blower Motor Power Transistor (2001-2007 Honda Civic)

Location: Behind the glove box.

 

That video also shows you how to test.

 

Thanks for that.

I don't know if this will matter but my car is a hybrid 1.3L engine. After reading a bit about the fuse box it seems there are some differences. ???

I've already taken out the transistor but pins 3 and 4 measure to 1500 ohms so that seems to be correct. I also checked the under-hood fuses which seem OK. I haven't done under dash yet for the cooling fan relay fuse (#26).

jom

 

I think you need to check the diode. Read thru that tutorial. That tutorial also has a link to that'll show you how to check the blower motor as well.

 

Thanks

I have NOT done a complete check of the transistor....I can't do the one test using the AAA battery as I don't have anything to hold the battery AND the transistor AND the DVM all at the same time. I only have two hands. :D

However, I did run the check where you bypass the transistor. When I turned on the key the fan came on! So I guess it's a good guess the transistor is, in fact, bad.

I'll do the AAA bat check tomorrow to double check.

Thanks again!!

jom

 

When you bypassed the transistor, did you have cold air coming out the vents?

 

Honestly, I did leave it on long enough...I only had a very small wire shorting the connection and, naturally, the wire got very warm. However, I don't think my A/C is bad but I'll soon find out.

I did finish my transistor check and it does not short the source/drain connection when you bias pin 1 high...so the transistor is bad it seems. I've already ordered one from Amazon. I also got some air filters for the fan and I'll replace those as well while the glove box is off.

Thanks

jom

 

Replace the blower motor resistor/transistor, then check the A/C, if blower motor is not working the evap. will freeze up right away and the A/C thermostat will shut off the A/C. 94

 

All checked out. Blower motor was drawing maybe 250 mA so that was fine. The A/C is working and all is well.

The scenario you describe above was exactly what was going on.

Thanks everyone for the help.

jom