DVexile

Wow, truly awesome thread.

I've got a 2007 LX manual transmission which went from perfectly working A/C to suddenly no A/C while driving. Based on the info in this thread I've diagnosed:

- Clutch plate on compressor pulley never turns, so apparently the clutch is not activating and that's why no cold air.
- Both fans turn on when I hit the A/C button, so apparently system has enough refrigerant and the A/C system is trying to turn on.
- Swapped "snowflake" relay and the radiator fan relay. A/C still doesn't work, but radiator fan does still work so apparently the relay is just fine.
- Checked voltages on relay socket pins from battery negative (vehicle ground), one end of relay coil and one end of relay switch have 12V on them so the system is trying to activate the relay and one end of the switch is powered.
- Checked voltages using plus terminal of battery and the end of relay switch that was 12V before is now 0V as expected, but the other end (to the clutch coil) is also 0V indicating it would appear open circuit to the clutch coil.
- Measured resistance to ground of center pin of three pin connector on top of the alternator and it is high impedance.
- Inspected with a cellphone video the ground connection for the clutch coil and it looks OK (i.e. I turned on cellphone light and held down the front of the engine while recording to get a decent look at the ground point).
- Can visually see bullet connector for the positive side of the coil is connected, couldn't easily get in there to ohm it though. Assuming that connection is fine.

So based on all that I'm concluding the coil on the clutch is toast and needs to be replaced. Does that seem right? Anything I could be missing as far as a root cause?

Also, I don't have the tools on hand (pulley extractor and right snap ring pliers) nor to be honest the time and patience to tackle this one. I'm sure a dealer will tell me to **** off and offer a "by the book" charge of multi-thousand dollars to depressurize the system and remove the compressor to do the clutch coil replacement. So I'm guessing I'll go to an independent shop. Think if I explain the procedure to do the swap without disconnecting the compressor from the system and provide the part someone will just charge me the hours of labor? Any other advice about getting a shop to do the coil change?

Thanks! This thread was a lifesaver for me so far!

ezone

Based on what you wrote, I'd say the same.

Next question, does the clutch plate turn? Make sure the compressor did not lock up.
Does the clutch plate appear as though it's been baked (severely overheated)?

Regardless, I would replace the clutch and pulley set along with the coil.
Call and ask. Some of us don't need to rape and pillage to make our living, but most of us will make the estimate 'by the book' adding whatever is allowed in the labor guide, and that probably would include recovery and recharging of the freon.
Just guessing, I'd expect you to pay in the neighborhood of at least 3 hours labor.

Have you priced the clutch and coil set yet?

DVexile

Good thinking. Just tried it and it turns freely by hand just fine.

I don't think so, but I attached a picture to see if you think it looks OK.

So is the thought here that perhaps something made the coil fail and that would be the clutch, once you've got it apart you might as well replace both given the labor cost?

Definitely some dealer service centers are just fine, I've used some quite happily before. I just know the one in my area isn't one I'd want to deal with and I have a lot of good independent shops in the area. Probably the independent shops will want to remove/capture/recharge anyway as with labor it might just make the most sense rather than fussing with it through the wheel well.

Online looks like coil is about $75 and the clutch is $200. Guessing expedited shipping will still be cheaper than buying at local dealer parts but will check that Monday morning.

Thanks so much for your help!

ezone

Pic doesn't look horrible.

Overheating can cause the coil to fail, and overheating could have been caused by things such as clutch slippage from excess gap or a weak magnetic field.
The coil could just be bad without outside cause too.

The mating surfaces of the clutch plate and pulley wear with use, eventually it can cause problems so I try to replace them if they have to come off. I just did one with 150k that had enough wear to quit working when it got hot.


This post has pics of that clutch and pulley alongside a brand new set: https://www.civicforums.com/forums/1...ml#post4686732


And, the bearing in the pulley wears too. I think it covers my butt to just do the complete set.

DVexile

Got it, thanks! Only 60k on this vehicle but I agree that if I'm paying someone to tinker in there I might as well do both the field coil and clutch at the same time since the clutch is a wear part.

Thanks again to you, and everyone else in this thread. Made it a breeze to diagnose the problem!

SMELZBAD

Awesome thread guys...pretty sure I'll be doing this job soon...losing ac after car heats up in hot weather...will be checking resistance on the coil tonight to confirm.
Wondering what people's thoughts are on a non OEM replacement coil? After all, how good can the Honda one be if they are a common cause of failure?

(2007 lx sedan...bout 80000kms)

SMELZBAD

Awesome thread guys...pretty sure I'll be doing this job soon...losing ac after car heats up in hot weather...will be checking resistance on the coil tonight to confirm.
Wondering what people's thoughts are on a non OEM replacement coil? After all, how good can the Honda one be if they are a common cause of failure?

(2007 lx sedan...bout 80000kms)

ezone

Check the air gap too. If it's too wide that will also cause the clutch to quit engaging when it gets hot. Much simpler and quicker band-aid fix if that's the issue.

Note the brand of the clutch relay, that's another big problem item. Omron is original brand, Mitsuba is the improved replacement.

SMELZBAD

Thanks for the reply. And great advice.
If the resistance of coil is good I'll likely get away with simply replacing the relay or removing a shim (would be sweet because I'd avoid the snap ring headache). Will be doing the complete clutch inspection this morning...fingers crossed.
And thanks for the tip about Mitsuba relay!

SMELZBAD

Follow up:


Just finished checking things out...

coil Resistence: 3.5 ohms...right on the upper end but should be good enough...

gap was .020 in
if I had some thinner shims I would have replaced the one that was on there now but was not to be.
This is the gap once you stick the feeler gauge in more than about 2 mm...there is a wider gap right at the edge of the pulley that was > .3 but I'm assuming you have to go in to where the plate that engages is to measure the gap???

Will replace the relay when I can and then see what happens next hot day.
I'll also try to get some thinner shims and try that next if the relay doesn't solve it.

Just wanna mention for anyone who will be removing the mounting bolts for the compressor that three of them are nice and shinny because they are fully contained within the compressor mounting bracket...the fourth...the bottom left when looking at the engine from the front of the car emerges near the oil filter and is corroded...sprayed with a bit of lube and really took my time getting this one out so as not to overheat it and break it off.

ezone

Using feeler gauges in a clutch that already has a lot of wear can be misleading, that's why I prefer to use a dial indicator and measure actual movement.


Watch as the clutch engages and disengages in operation, does the movement of the outer plate LOOK like it's moving a full millimeter or more to engage?

How thin is the shim already in place? Usually you just take it out and clearance decreases to a point where it will work consistently again, until it wears a bunch more.

Clearance (air gap) spec is .35mm-.65mm (or .014"-.026")

SMELZBAD

The shim in place was like .030 or real close to it...tried with it removed but clutch was rubbing on the pulley.

ezone

Maybe I didn't catch this earlier or I was in a hurry and read it wrong:
Here you said gap was .20, did you mean .020" (inch) or was that in millimeters? ??
.020" (inch) would be within spec, yes?
0.20mm would be tight.
0.200" would be a huge gap.

No shim removal should be needed if .020" was the actual clearance.....but like I said, it's hard to determine and you can only stick the feeler gauge in just a smidgen to get a decent read.


You had it apart, so you had to see just how the clutch and pulley wear in such a way that feeler gauges can't just be shoved in to get a reading LOL


When it quits cooling and the compressor is not engaged, make sure the radiator fans are still running (The PCM turns on the compressor and fans together, so if they are not running that's indicating a different issue altogether)

I may use a prybar or long screwdriver to check if there is a magnetic field present at the clutch...If it attracts the screwdriver I know it's receiving power from the relay so it must either be a gap issue or weakened field strength issue.. Use the tool to push on the outer plate and see if it clicks into engagement again.

Relay check or just replace because it's cheapest, and ohm check the field coil while it is inoperative if you can catch it in the act.
The field coil windings (approximately 13 miles of extremely fine wire) can go open or partially short just in certain temperature ranges and make it real difficult to prove failure.

SMELZBAD

Sorry about the unclarity...corrected my error.
And thanks for the tips...I'll be sure to follow up with them if I have more issues after the relay replacement.

lindomar85

sorry to hijack the post..


I have 2007 civic si sedan..
2 passenger side ac vents blow cold air and the 2 driver side vents blow hot air..
I disabled/bypassed the heater(no engine coolant running to heater core)


what could it be?

ezone

Cold air on one side of the dash and warmer air on the other side, usual cause is low refrigerant charge. Probably needs the freon topped up or recharged, and inspect thoroughly for evidence of leakage.


Assuming the car does not have dual-zone climate control.