bravo79

i was able to open the 1p connector today. It does have voltage so this means the ac system is telling the clutch to engage but maybe the thermal protector is bad?

ezone

If you have 12v+ there while the system is turned on that should verify the relay is working and wiring up to the connector is ok.

(engine off, key off)
Next ohm check the other side of that connector to see if the circuit to the clutch has about 3.5 ohms resistance.
If you pass that check, then the thermal protector is good and the field coil is good.

Apply 12v to the clutch and see if the clutch plate engages (clicks)....if no click, push on the outer plate of the clutch and if it clicks and sticks to the pulley then the air gap is too wide (remove a shim(s) to reduce clearance, desired spec is 0.5mm air gap).



If you did not find around 3.5 ohms in the previous check, then open the bullet connector (shown in that one large pic) and recheck field coil resistance directly at the red wire with the male terminal (right side in pic)



Those resistance checks are done with the meter black lead on the battery neg post.
Do not unbolt the small ground wire for the compressor clutch, leave it alone for testing.




If you want to ohm check the thermal protector, open the bullet connector and test between the connector you had trouble with and the female half of the bullet connector (left side in pic) Protector is supposed to have continuity (zero ohms)


HTH

bravo79

I believe I need to remove the power steering and the alternator to do the second part of these tests

ezone

Yea there's almost no working room if you actually have to get down there. I haven't got a car to look at but I think it can be done without alt and ps removal.
Hope the first ohm check shows coil good and you just need to change the air gap to get it to engage again.

bravo79

(Next ohm check the other side of that connector to see if the circuit to the clutch has about 3.5 ohms resistance.)

No ohms there. The meter doesn't read anything. I guess I Have to open the power steering and the alternator or just wait for the weather to cool down. In the middle of this I got another CEL code which keeps coming off and on.

musang77

I plan to have a go at my 2004 Civic 1.6 shortly. The air con is intermittent, typically running for about 15 minutes then disengaging. Cooling fan keeps running. Air is very cold. The plan is to remove a clutch shim first, as the air gap is about .75 mm.

Basic question - what exactly is the thermal cut-out triggered by? The compressor casing getting hot? If so, might I presume that means high friction inside it?

Many Thanks - musang77

ezone

Desired spec is .35mm-.65mm, seems your .75mm isn't far off the mark if that's accurate.

Yes, the temp sensor is kinda glued into a little pocket in the compressor housing. You can probably see if it you look.
However, if that shut the system down the radiator fans would have also quit running.

musang77

Darn that was fast!

Looks like the thermal switch is eliminated as a cause.

The early part of this thread made reference to the clutch relay. Neither the owner's manual (UK version) or the Haynes manual have a relay list that I can see, so which of the three air con relays (going by the symbols in the cover) is it?

I will have a shim kit from Honda tomorrow morning. Reasonably priced at approximately 5 of your American dollars I thought I might as well have some on hand. The dealer said they never have to change the shims, so don't know whether it contains various thicknesses, or whether its just one. . I guess they just replace the whole clutch or the whole compressor......

Many Thanks - musang77

ezone

Oh carp, I don't have wiring diagrams for anything outside of North America.


Some thermal protectors ARE wired to interrupt ONLY the compressor clutch.... The compressor would have a single wire harness connector if that were the case.

If the compressor harness has a 3 wire connector, the thermal protector would disable the entire AC system including the radiator fans.
===================

Removing a shim (when possible) will decrease clearance.

Might need to ohm check the coil WHILE it has quit working too. They can go open circuit intermittently.

====================

Post a pic of your engine compartment fuse box?

Most of ours have a plain snowflake symbol indicating the compressor clutch.
A snowflake inside a rectangle is for the condenser fan.



Gotta run, I have work to do!

musang77

Hello ezone,

same relay box as in post number 12.

I'll try new relay first.

many Thanks - musang77

musang77

Good Day -

I appear to have fixed it by removing the shim. Tried swapping relays around first of course.

Soon after starting, when I would have expected it to run for about 20 minutes, the compressor + cooling fan would run for 8 seconds, then both stopped for 11 seconds, this cycle repeating precisely, so I assumed ECU commanded rather than a thermal or relay input. I then realised the fan speed control **** was out of Auto, on the lowest manual speed notch. Setting Auto again made the cooling fan and compressor run continuously.

I mention this in case someone else sees it.

Anyway, there was a single <0.5 mm shim which I removed. The clutch plate was fairly rusty but I had no way to grind it with any accuracy so reassembled it. It still turned by hand with the same resistance, and no scraping. Took it for a long drive and all seems well.

Many Thanks for the excellent information and instruction on here, delivered at a level I can assimilate! I'm sure there's lots more for when I next have issues.

If my air con isn't fixed, and its just stringing me along for now, I'll let you know.

Incidentally, the Honda shim pack consists of 4, of varying thicknesses. Not sure whether that was mentioned on this thread.

Regards - musang77