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A/C Compressor clutch not engaging

Hutch532

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Hey folks,
Going through a rough patch with this damn car. After fitting a new caliber the other week, to servicing and boots not opening, well you get the idea. The latest problem is involved with the air conditioning. It wasn't blowing as chilly as I like it (being Scottish, it wasn't feeling homely enough) so I decided to re-gas it as the pressure was a little low. That's all fine and well and at the right pressure, but part of my check was to look at the compressor clutch.........NUTS........clutch isn't engaging. Looking for a little advice as to whether I can free it off (calibrated tap...), relay check (where is the relay haha???), or any other suggestions.

Thanks in advance!!!

Chris
 

freddofrog

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The compressor clutch relay is in the main "under-hood" fuse box, there's a fuse in-line with the relay-coil.
You need to check both.
 

Bigfish084

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Did you get to the bottom of your air con issue? I'm having a nightmare with my car also (2009 2.2 iDtec ES GT). Everything is going wrong at once! When I press the Aircon switch the engine revs drop slightly so something is happening. Can't hear anything engaging though. Regassed, changed the relay, checked the fuses but still not engaging. This damn car is doing my head in. No problems whatsoever for the last two years and now everything is going Pete Tong!
 

freddofrog

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On the 7th gen diesel, the A/C pressure sensor is down in front of the condenser and is a common failure on the 7th gen diesel.

The diesel also has a valve so that the A/C can run in reverse as a heat pump to heat the cabin when the outside temperature in below 5 C and the engine is cold. This has not been an issue in the 7th gen diesel, but is still worth bearing in mind.
 

Bigfish084

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freddofrog said:
On the 7th gen diesel, the A/C pressure sensor is down in front of the condenser and is a common failure on the 7th gen diesel.

The diesel also has a valve so that the A/C can run in reverse as a heat pump to heat the cabin when the outside temperature in below 5 C and the engine is cold. This has not been an issue in the 7th gen diesel, but is still worth bearing in mind.
Thanks but I'm sure mines an 8th Gen? Unfortunately I only drive the thing. I don't know what makes them tick. It's at my local dealer on Thurs for a service and MOT. I'll let them "plug it in" see what's wrong and no doubt relieve me of a few quid!
 

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Bigfish084 said:
Thanks but I'm sure mines an 8th Gen? Unfortunately I only drive the thing. I don't know what makes them tick. It's at my local dealer on Thurs for a service and MOT. I'll let them "plug it in" see what's wrong and no doubt relieve me of a few quid!
Being a 2009 iDTEC it is 8th gen but, apart from different locations of sensors and a more comprehensive interaction with the Honda HDS (their plug-in diagnostic tool), the aircon system in the 8th gen is functionally similar to the 7th gen. I know the aircon system in the 7th gen petrol and 7th gen diesel extremely well, and I also know that dealers have often mis-diagnosed issues on the aircon on the 7th gens (this forum is littered with tales of woe) - usually saying that the compressor was faulty when it was either the relay or the pressure sensor.

The valve and pressure sensor on the diesel is different from that on the petrol version - on the 7th gen diesel they are located in front of the condenser, in the 8th gen diesel they are located behind the bumper. All I would say is this - if you are going to rely on a dealer to fault-find the aircon, unless their plug-in diagnostic can absolutely guarantee the fault (which it wouldn't on the 7th gen), then watch out for expensive parts swapping.
 

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I've actually had this car on my hds and you can trigger the aircon compressor from the manual functional test, so the relay and wiring is fine. But the clutch isn't actually engaging so to my mind it's either the compressor itself.. Or as you say the pressure switch.

Daryl rather than let your mot tester check it, find an Independant aircon specialist, a lot of them are mobile and will be able to diagnose and solve it.
 

Hutch532

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Hi, a little further forward but no solution as of yet. Sorry its taken a while to reply, been away with work. I've been to Honda just to enquire about cost of parts. They were kind enough to lend me a relay to slave in, and discount that from the diagnosis. I also shorted a split pin across the terminals, and still no clutch engagement. This would point at the compressor or the pressure switch (which I hadn't thought of). New parts are eye watering so having had a look at eBay, the sensors and compressors are similarly priced, so shall try one of them and hopefully get it fixed, as driving motorways with the windows down is becoming a pain haha!

Chris
 

Bigfish084

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It's the compressor itself that's gone. Had it checked by an independent specialist. Unfortunately though he has never changed one in an Accord so can't give me a price for the labour. I've got a used compressor in the boot of my car but nobody to fit it!
 

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We can probably fit it mate. Probably worth doing same time as your DPF when you book it in. We will have more access when DPF is off the car
 

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Hutch532 said:
Hi, a little further forward but no solution as of yet. Sorry its taken a while to reply, been away with work. I've been to Honda just to enquire about cost of parts. They were kind enough to lend me a relay to slave in, and discount that from the diagnosis. I also shorted a split pin across the terminals, and still no clutch engagement. This would point at the compressor or the pressure switch (which I hadn't thought of). New parts are eye watering so having had a look at eBay, the sensors and compressors are similarly priced, so shall try one of them and hopefully get it fixed, as driving motorways with the windows down is becoming a pain haha!

Chris
You can remove the relay and check if the compressor clutch is working without even having the key in the ignition.

The aircon relay on the 8th gen diesel is located as in the schematic below (click to enlarge)



pinout of the relay (clck to enlarge)





remove the relay, and in the relay socket, measure the resistance between pin 2 and ground (click to enlarge)







it should be about 4 Ohms (maybe a bit more). If it is open-circuit then the compressor clutch is electrically dead.

If there is resistance, you can check to hear the clutch pulling in by connecting a wire from the positive terminal of the battery to pin 2 of the relay socket - DO NOT LET THE WIRE TOUCH ANYTHING ELSE

you should hear the clutch pull in, if it doesn't pul in yet you measured electrical resistance, then the clutch is jammed


Finally, a few more diagrams in a post in another thread http://typeaccord.co.uk/forum/topic/21792-air-con/?p=232636

note the inbuilt diagnostic in the 4th picture
 

Salim

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On the 7th gen diesel, the A/C pressure sensor is down in front of the condenser and is a common failure on the 7th gen diesel.

The diesel also has a valve so that the A/C can run in reverse as a heat pump to heat the cabin when the outside temperature in below 5 C and the engine is cold. This has not been an issue in the 7th gen diesel, but is still worth bearing in mind.
Old thread but i did not know these had that. Even so my diesel took an absolute eternity to heat up :(
 
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