AC issue, fixed twice broke again

DevilDog89

New Member
Brand new here thanks to this issue actually. So my AC didn't work earlier this spring, discovered that my compressor wouldn't kick on. $5 relay later my compressor worked... until the next day. Compressor quit turning on but my new relay still metered good so then I went to the compressor clutch. It was now reading open and the bearing in it started going bad all the sudden, so I replaced it of course. Two birds one stone cold air again for two days this time, very cold air at that. Now my compressor stopped engaging once again and I'm guessing at this point. Please help, I've just downloaded the service manual and I'm questioning my level of charge. Thanks
 

DevilDog89

New Member
I agree, I feel I've been chasing the problem with bandaids. My phone won't let me open the manual so I'll have to reformat it or find it somewhere else. The condenser fans do run loud and proud as soon as I turn the ac on every time. I replaced the compressor clutch only and I installed the two shims that were included with the new hardware. I admit I did not actually measure the clearance with a feeler gauge as I don't own any yet.

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These are a couple diagrams I found, the clutch I replaced also came with a new thermal switch and connector that I also installed with the new clutch.
 


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DevilDog89

New Member
Do you mean the ecu module under the hood next to the fuse box? I searched for the pcm as its referenced in the diagram but still can't find it, unless they're the same thing
 

HeX

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When was the last time the freon was flushed, if at all? Its possible that you need fresh oil in the system, which is mixed with the freon.
 


DevilDog89

New Member
It's been far too long to be honest, I even tried one of those refill cans from Walmart when the problem first arose. Now, after learning a lot from all of this, I'm afraid I might have over pressurized the system. But I don't understand why or how it worked for a day or two before it quit each time.
 

DevilDog89

New Member
Advice: Save yourself money, time, and frustration by learning to do diagnostic tests rather than throwing parts at the problem.

See post #4.
This is true, I troubleshoot for a living and that's how I discovered the bad relay and bad clutch. I only tried the refill can after I replaced the relay and the cold air died off a day later.

Whenever I get ample time to, I'm gonna check that voltage and then ground it and go from there.
 

DevilDog89

New Member
Haha yeah, that's how I ended up here. I'm gonna try to meter that wire today btw
Unplug ECU connector A.

Turn key to ON(II) [engine off].

Do you measure battery voltage on the red wire at pin A14 (marked in diagram below)?

If so, ground the red wire to the metal chassis. Did you hear the compressor clutch click?
I measured around 12v at pin 14, I grounded the pin and heard the compressor relay click. I did not hear the clutch itself click

I also double checked the coil and the thermal switch, they both ring out good. 6 ohms on the coil, 3 ohms on the switch
 
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DevilDog89

New Member
Hurray! First I couldn't spell mechanic now I are one! Haha

I'll check for voltage just to be certain, but I'd put my money on the gap issue like you said. When I replaced the clutch, I removed the old clutch and it's one shim and installed the new one with one shim first. It made constant contact with the new pulley so I opted to install the second shim, afraid that one shim would under gap the clutch and constantly run the compressor. I should have bought feeler gauges and done the job the right way the first time but I was under a severe time crunch and my civic had to run to take me to work.
 

DevilDog89

New Member
Checked for voltage at the coil, got 0 volts. I rang out the coil again and read 2.5 ohms, I rang out the coil through the harness it came with and got 5 ohms. I double checked my voltage at the ecu and still had 12 volts and the relay still clicks when that pin gets a ground. I checked the shims also and together they are still thinner than the stock shim so the gap is not too large. Somewhere between the coil harness and the ecu the power signal is lost
 

DevilDog89

New Member
I also just went back and rang out the signal path from the ecu pin A14 and the ship side connector to the compressor coil harness. I read 0 ohms on the whole connector, I don't have a diagram to know if that's bad. I read 11 volts on one pin that hooked up to the thermal switch but 0 volts on the pin that hooks up to the coil. Then I reinstalled the ecu and pulled the relay, I read 133 ohms to ground on one pin in the relay socket in the fuse box, the rest were open to ground.
 

DevilDog89

New Member
Oh yeah I'm an avionics technician at Honda Aircraft Company, I read wire diagrams for a living. I'll be able to pin point the issue for sure, I'm quicker to ask questions when I'm working on cars. I'm less experienced with cars than I am with planes so I prefer tapping yall's experience. I just don't understand how the system worked after I replaced the relay and again after I replaced the compressor clutch. If there is an open in the wire path, it should deny any operation at all regardless of other failing parts. Obviously I get hung up on stuff with cars lol
 

DevilDog89

New Member
I just studied that diagram some more (three kids under 5 keep me busy btw) and realized that the relay socket I tested with 133 ohms appears to be growing an open and should be short to ground through the coil. Correct me if I'm wrong but that appears to be the case, in line with your advice.

I suppose the intermittent aspect threw me off both times, steering me away from the true problem. I'm not ignoring anything though, it's been clear to me once I metered everything today that I have an open somewhere. I didn't study the diagram while I was doing the work earlier today but I made progress all the same. I'm not lost or stubborn, just less experienced.
 
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DevilDog89

New Member
Have you done the tests I suggested?
No not yet, I'm a family man with little spare time. I'll get it done soon though.

Post pics of the connector(s) and mention where it's located.
When I mess with it again, I'll entertain your request for everyone's benefit.

If you study the circuit diagram, it tells you that the thermal switch voltage is irrelevant to this discussion and to your problem.
I'm aware of this, I'm simply being explicit for the sake of being thorough.

With red wire at ECU pin A14 grounded and key in ON(II)? It's hard to interpret measurements you post without the test conditions.
Yes, I read voltage with the red wire grounded and the key in the ON(II) position. Forgive the assumption

Which specific pin shown in the circuit diagram? Post pics.
Again, I'll be sure to take pictures when I return to test further and seek out the issue.

The service manual will show you an illustration of how the pin numbers in the circuit diagram correspond to pins of the relay.
I'm still having trouble with the service manual but I'll be sure to find out exactly what pin I'm testing.
 

DevilDog89

New Member
Here is a diagram of the relay socket from the service manual I found http://civic.hondafitjazz.com/A00/HTML/00/SNB6E00J54211512411FEAT00.html.

I rang out the relay socket with the engine off no power and read open to ground on pins 1 and 3, 5 ohms on pin 2 and around 125 ohms on pin 4. I rang out to ground with engine on, A/C on and read open to ground on pin 1, 4 ohms on pin 2, 7 ohms on pin 3, and no reading on pin 4. I checked power with key ON(II) engine off A/C on and read 0 volts on pins 1, 2, and 3, pin 4 read 11.5 volts. With engine on, A/C on, I read 0 volts on pins 1, 2, and 3, and read 14.2 volts on pin 4.

I also disconnected the compressor plug that's mounted to the alternator and read around 11 volts on pin 1 and 0 volts on pins 2 and 3. Pin 2 sends power to the compressor coil, so it would seem that voltage never reaches the plug. DSC_0108.JPG 1495811613103-1737443498.jpg
 

DevilDog89

New Member
The fit/jazz link you posted is for the relay, not the relay socket.

With power off, only one pin in the socket should show continuity to body ground (pin 2 in original circuit diagram), assuming you did not unplug the compressor clutch coil.

What you are calling pin 3 is pin 4 in the original circuit diagram.

Are your tech skills telling you what the problem likely is? Mine are suggesting several possible problems, one of which is a bonehead easy fix.

Can you find Waldo?
You have a suspiciously funny way of putting things, but I appreciate your help regardless. I think I have a short to ground, I looked at my link again which does have a relay diagram if you click the second gray button. I realized that it diagrams the relay pins looking at the relay from the bottom, not the socket so I got the pins backwards. I already know that I have a physical issue with a wire, that's obvious just like Waldo. Pin 3, not 4 is short to ground. I've been planning on pulling up that fuse box and searching for that short in the wire since the last two times I rang out that relay. What else would you suggest besides that? What are the several other problems you're getting out of this besides the short? Let's ignore my incompetence and fix my car instead
 

DevilDog89

New Member
I understand how the relay works, there's a small electromagnetic coil inside that attracts the switch arm when energized and closes the other side of the circuit allowing voltage to pass from the battery to the compressor coil. I know that the relay receives power on pin 3, the ecu provides a ground to pin 4 when commanded by the AC switch in the cabin, and the relay properly functions with an audible click when energized. At that point, the relay swith is closed and battery power from pin 1 is not present to go across the relay to pin 2 to turn the compressor on. Is that getting close? Perhaps my battery line in the circuit is flawed? Pin 1 is also not short to ground at all so where is the voltage? That leg of the circuit should be hot with the engine on correct? I'm not having an epiphany, at this point idc how stupid I look I just want my AC to work
 

DevilDog89

New Member
The fuse of course, and I now know why we've gone back and forth so much. I've already checked that fuse at some point before I joined this forum and it was fine at the time. I failed to mention that I checked it and now here we are lol. I will check it again and post the result, I hope that's the cause but I'm afraid that is still fine as when I first checked it. I also did not meter it's resistance like I should have, that's the true test. I'm glad I'm not as myopic as it was beginning to seem, I still don't understand how I have any continuity to ground on pin 3.
 

DevilDog89

New Member
Just forget about it. Based on your own test results, it clearly is NOT a problem.

Stay focused on real problems, not imaginary ones.
125 ohms to ground is not imaginary, that is little resistance to ground and can easily be a problem especially since it should be open to ground like you mentioned earlier.
Did you test the correct fuse? Please convince me.

How did you test the fuse? The best test is measuring voltage on BOTH fuse test tabs. Both should read battery voltage.
Yeah I checked the correct fuse, it's clearly marked on the cover. I eyeballed the fuse without a meter and it appeared fine. I just checked it tonight with my meter and it was clearly blown reading completely open, not how it appeared the first time. I tested the new one from the fuse box cover and it read 1 ohm so problem solved right? No, I installed it, turned on the engine and the AC to full blast and still the compressor did not engage. I didn't meter the rest of the system as I had to corral my kids inside for bedtime, I'll try to do that tomorrow. How would I test it for voltage? The tabs are fully recessed and covered when it's installed so I would not be able to probe it.
 

DevilDog89

New Member
You read lower ohms for the coil. Is that a problem too? Is your battery draining overnight? Is voltage low on that part of the circuit?

See the forest through the trees.



Haha



Take the next logical step. Did the fuse blow again. Chances are that it did.



Inspect a spare fuse. The TOP has two tiny square tabs. The pointed tip of a multimeter probe should yield interesting voltage results, which are also the best way to test for a blown fuse.
Gotcha, I'll probe the top of the fuse after I make sure it's not blown. I didn't run the engine that long but it could have blown right away. What would come after that? What could be causing high current?
 

DevilDog89

New Member
You're close now.

Voltage to the fuse is constant, no key required. The fuse may have blown immediately upon installation.

Do this:

Remove relay.
Install new fuse.
Measure voltage on both tabs.

What does it mean if one tab reads battery voltage and the other reads ~0V?
If this happens, what is almost surely the problem?
The answer should look like a huge Waldo on a small white piece of paper.
I removed the relay first and then checked the new fuse from last night which was blown, so I replaced it with a ten amp fuse only for the sake of testing. I know that's not right and potentially harmful to the system but I only installed it long enough to test with the engine off and key removed. I measured 12.5 volts on both sides of the fuse then immediately removed it. So voltage obviously flowed across the fuse like it should have despite what amperage it should be.
 


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