joeymc13

So, I spent part of the day trouble shooting. fuse #13 underdash blows as soon as ignition is on. Unplugged the 3 relays in underhood fuse box (that is the circuit that fuse #13 is supposedly protecting), fuse still blows with ignition. When the fuse blows, I have no dash panel a/c power, no a/c blower, and irratic idle... revs up and down once warmed up.

I figured that since the fuse still blows with all 3 relays unplugged, I had a wire grounding out, so I tested the output side of fuse #13 for continuity to ground, sure enough, there is a short. I downloaded a wiring schematic for the vehicle, and found that the output of #13 is a black/yellow wire. I found about 5 18awg black/yellow wires leaving the fuse box, and found the one that was grounding out. I cut the wire, replaced the fuse, turn ignition on, it doesn't blow.

I traced that bad boy down, all the way to the compressor relay, and once unplugged, found that the red wire to the compressor reads ground. In a nutshell, does this mean my compressor coil is shorted out? How could this have happened, and anyone know where I can find a cheap compressor if this is the case? (I didn't want to jump the pins with a paper clip or something in the relay socket bc of the fact that I had ground on the red wire, when I believe it should read as an open circuit.)

I'm not a mechanic, but Im deadly with a DMM (I've been installing mobile electronics on cars, boats, and aircraft for 10+ yrs), so I could have all this completely wrong... I just know that I unplugged the single pin harness with the red wire going to the compressor, and the fuse doesn't blow, and the blower motor and a/c controls function as normal now, just obviously, no compressor engaging, and no cold air.

Joey

Former User

1) I thought the A/C power relays were not located in the hood fuse box but in the front left of the engine bay:



2) It's also puzzling that the red wire leading to the compressor, where you found a short to ground, is not protected by fuse 13.

joeymc13

Wow, obviously my first time on honda-tech, thanks so much for the fast reply. Yes, fuse #13 does protect the compressor, It's not blowing now bc I disconnected the single pin harness that leads to the compressor. I looked up the labeling for fuse #13, and it is labeled as rear defogger relay, cooling fan relay, and another relay, I've forgotten by this point, but all three relays were in the under hood fuse box...

joeymc13

I suppose I should state that yes, you are absolutely correct, the compressor relay and condensor fan relay are where you stated. I traced the wire by using continuity to the underside of the underdash fuse box, then to the a/c compressor relay, which is on the front driver's side, next to the radiator.

Former User

If you look at the circuit diagram, the compressor clutch is not on the fuse 13 circuit. In general, a short to ground from the compressor clutch would blow fuse 35 but not fuse 13. Therefore, you would seem to have at least two separate shorts.

A common location for a short in the compressor clutch circuit is the clutch coil. In this case, all you need to do is replace the coil. This job can be done without even removing the compressor.

joeymc13

Thanks RonJ,
From what you stated, I too, am puzzled that fuse #35 does not blow, only #13. But yes, my guess was the coil, I just don't know too much about this stuff, felt better about asking for advice, than assuming. I'll have the coil replaced, and go from there! Thanks...

Former User

Before you replace the coil, verify that it actually has the short.



Unless you know what specific Blk/Yel wire that you cut, any of these components may have the short that is blowing fuse 13:

joeymc13

All black/yellow wires are reconnected. I'm fairly confident the short is at the compressor. The only wire not connected, like I said, is the single pin red wire harness underneath the compressor relay, and the fuse stays intact now with ignition on. My car is a dx model, so I do not have pwr mirror, I do not believe I have ABS (I checked for the computer on the passenger side of the trunk, and for another power distribution center for ABS on the passenger side engine bay, but neither was present.) The car is fairly new to me, I do not know much about the history of the vehicle other than it has a d16y8 swapped into it. The only things from that last diagram that I have in the vehicle that is in-op right now is the condensor fan, and the compressor. I'll ohm out the coil tomorrow in the daylight and confirm resistance, I did try spinning the inside of the compressor by hand, and it seemed to spin easily. You've been very informative, thank you for volunteering advice, if you have anymore, I'll gladly accept! If it helps in the trouble shooting process, as I was driving for the last cpl days with a/c on, I could feel the compressor kicking on and off prob every 3 or 4 seconds as I was driving down the interstate...

joeymc13

Also, while trouble shooting, I tested for continuity to ground at the compressor fan, blue wire, and I found zero resistance, so I ran 12v+ to the blue wire, and another ground to the black wire (with relay unplugged) just to make sure that the condensor fan wasn't burned out, and it functioned fine, if this helps any with finding a solution to the situation...

Former User

When you reconnect the red wire plug for the compressor clutch, fuse 13 again blows, right? If so:

1) If you remove the compressor clutch relay, does this prevent fuse 13 from blowing?

2) If you remove the condenser fan relay, does this prevent fuse 13 from blowing?

3) If you remove the compressor clutch relay and install the condenser fan relay in its slot (fan relay empty), does fuse 13 still blow?

joeymc13

One last post... With the compressor relay plugged in, but the single wire harness (red going to compressor) unplugged and a/c on, I did read 12v+ from the red wire output of relay to compressor, I've just got ground coming from the compressor up to the other side of that single, red wire harness...

Former User

This is again puzzling. Something is wrong. Your test showed a short to ground on the blue wire, but wiring the fan to the battery failed to confirm a short.

When you say zero resistance, do you mean zero resistance (high continuity with ground) or infinite resistance (no continuity with ground).

joeymc13

When the red wire is reconnected, yes, fuse #13 blows.
With no compressor relay in place, #13 does not blow.
I have not tried removing condensor fan relay with ignition on, and fuse #13 in place yet, but I will do so tomorrow. I have not tried switching relays either, but I can also do so tomorrow.

joeymc13

I'm sorry, I did mean infinite resistance on the blue wire to ground (zero continuity).

joeymc13

Hey RonJ, I ohmed out the coil, read 3.7 ohms at 84 degrees f outside. I'm thinking replace the coil, its out of spec, would you agree? Any idea how this could've happened?

Former User

It should be about 2.8 Ohms at 68F, so I'm not sure it's bad. Can you measure resistance again when the engine is cold? Otherwise, slap some ice packs on the compressor and try again when it's chilled.

joeymc13

I measured the coil with the car already cooled, ambient temp was 84 degrees when I measured, It will get into the upper 60's tonight, I'll get out there then to measure.