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Air Con

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Had my 2004 2.2 CDti for a month or so and air con has not worked since I had it so finally got round to getting it serviced and re-gassed today:

They found no oil in the compressor so topped it up
They found practically no gas in the system so they have filled it
Check for leaks and there are none
They say they can see the clutch kicking in but still not working !! :-(

Any ideas where I should look to try and diagnose the issue?
 
Air con pressure switch, or radiator fan relay, air con fan relay, fault. As the clutch is engaging I would say pressure switch.


To replace Air con pressure switch,the air con gas needs extracting first as it regulates the gas within the pipework, if you just removed it ,all refrigerant would escape

The place where you had this done will extract it for you and hold it in the machine while the new pressure switch is installed.The switch is at the bottom left of the radiator looking from the front, held in a bracket, and is subject to abuse from stone impacts, rain corrosion etc. and easily damaged.

You can just manage to get it out from between the plastic grille slots, if I remember 36 mm long reach socket does the job.

Unplug the electrical connector >unscrew old sensor>, install new sensor> tighten >plug back on, re fill with gas.

I got mine here :-

http://www.ebay.co.uk/itm/A-C-AIR-CONDITIONER-PRESSURE-TRANSDUCER-SWITCH-SENSOR-HONDA-ACCORD-8-VIII-04-13-/301340153634?hash=item462945d722:g:A3sAAOSwGvhUL59K

CHECK THIS FITS YOUR MODEL YEAR WITH OEM HONDA PART NUMBER.

Or pay silly Honda prices for the same thing.

T.J.
 
there's an inbuilt diagnostic system for the aircon (on both 7th and 8th gens)

see this guide (the 7th gen guide)

http://typeaccord.co.uk/forum/topic/21770-blowing-hot-and-cold-air/?p=230336

the first 9 "sensors" are the same on both 7th gen petrols and on the diesel, but on the latter there is a 10th "sensor" not shown in the guide, which reads the pressure in the system

play about with the inbuilt diagnostic and it will help you to evaluate what is working and what is not working e.g. if all temperature sensors are good, and the 10th "sensor" (pressure) is giving reasonable values, yet the 5th "sensor" (evaporator temp) is warm, then this indicates a perished condenser - if you take the car along the A610 at 60 mph and the aircon starts blowing cold, it confirms a perished condenser
 
So had a look on the half hour journey home and the Evaporator out temp (5) ranged from 31 - 33 and the pressure sensor (10) only moved between 06 & 07. What's the units for the pressure and what's a typical value?

Also noticed pressure did not change when I manually turned the air con on and off.

Sent from my iPad using Tapatalk
 
Just looked under the bonnet and I can see two relays in the main fuse box with a snowflake on and one in the secondary box. Which one do I target?

Also are these a Honda only part or available anywhere?
 
Had a look through, checked a few fuses and swapped some relays where I could with identical ones but still no luck. Found the relay that provides power to activate the clutch and proved that's working fine.
 
You can swap over as you have done the clutch relay and the condenser fan relay to test.

Should you need one here is what I used in mine, I can't remember if it was the four or five pin version , as I was working on something else at the time ,but here's the link to who I used for both.



http://www.ebay.co.uk/itm/MICRO-Relays-5-Pin-Changeover-Contact-20A-12V-SEALED-PACK-OF-2-/290881893044?hash=item43b9e972b4


http://www.ebay.co.uk/itm/MICRO-Relays-4-Pin-Normally-Open-20A-12V-SEALED-PACK-OF-2-/301072119214?hash=item46194bf5ae

You can test the aircon pressure sensor on a petrol accord, but not the diesel.

See previous post for pressure sensor if needed.

T.J.
 
Grayedout said:
So had a look on the half hour journey home and the Evaporator out temp (5) ranged from 31 - 33 and the pressure sensor (10) only moved between 06 & 07. What's the units for the pressure and what's a typical value?

Also noticed pressure did not change when I manually turned the air con on and off.
Click to expand...
The pressure is supposed to be in MPa (Mega Pascals) where 1 MPa = 1 Bar

Normal operating range is 10 to 15 Bar

Those pressure values indicate either - not enough gas in the system, or, the pressure sensor is faulty, or, the compressor is not working internally.

It comes down to the statement in #1 made by the people who re-filled the system "they can see the clutch kicking in but still not working".

"they can see the clutch kicking in but still not working" is Valid


The engine ECU triggers the compressor clutch relay (the relay energises the compressor clutch). The engine ECU only does this when the aircon control unit gets correct signals from all the sensors in the aircon system, and then communicates (via the gauge control module) that the engine ECU can trigger the compressor when the engine ECU is ready to do so.
Thus, if the inner part of the compressor is rotating (i.e. they did "see" this), then all sensors and relays in the aircon system must be working, and the compressor is simply not compressing. This would show up as low pressure in the system, which the inbuilt diagnostic shows.



"they can see the clutch kicking in but still not working" is not Valid

This indicates one of two possibilities
1. as well as being incorrect about the compressor clutch, they were also incorrect about the gas refill i.e. still not enough gas in the system - maybe there is a leak at a joint where the gas is lost under pressure (when compressed)
2. although incorrect about the compressor clutch, they did refill the system properly, and there is no leak. In this case, since the inbuilt diagnostic shows low pressure, then the pressure sensor is faulty i.e. the controller tells the engine ECU to trigger the compressor, which it does, the compressor compresses the gas, but the faulty sensor shows no rise in pressure, so the controller tells the engine ECU to stop. The aircon controller then times out and tries again.



checking whether "they can see the clutch kicking in but still not working" is Valid or not

can you hear the compressor at all ?? If you cannot hear it at all, then the compressor is possibly faulty.

As a final check, go to my "diagnosing aircon problems" thread http://typeaccord.co.uk/forum/topic/10382-diagnosing-aircon-problems/ and do the first check. You do not need the key in the ignition. Just remove the compressor clutch relay (as shown in the pictures in #1 of that thread) and connect a wire from pin 2 of the empty relay socket to the battery positive, and you should hear a "clunk" from the compressor clutch. If you do hear a "clunk", remove the wire, leave the relay out, and start the engine. Set the target temperatures to LO, go to manual control of the A/C, set A/C ON, blowers to max, then connect pin 2 in the relay socket to battery positive,and feel if cold air is blowing. DO NOT LEAVE IT LIKE THIS FOR MORE THAN A MINUTE. If you can feel cold air blowing, hen the pressure sensor is faulty, otherwise, the compressor is not compressing (or no gas in the system). Note that doing this check with the engine running on the system in the diesel may bring on the "coil" light on the dash. This should eventually clear itself.
 
btw this picture shows the pin numbers on the relay


relay_pinout.jpg
 
Thanks again Brian. Confident the clutch relay is working fine as I can hear a clunk and can see the outer part of the pulley spinning when the relay is engaged and not spinning is off.

I'll check the rest later.
 
try the "wire in relay pin 2" anyway, if you can hear a clunk and then, with engine running etc, feel cold air you know that the compressor works fully and that there is gas in the system. If not, either not enough gas or faulty compressor.
 
freddofrog said:
try the "wire in relay pin 2" anyway, if you can hear a clunk and then, with engine running etc, feel cold air you know that the compressor works fully and that there is gas in the system. If not, either not enough gas or faulty compressor.
Click to expand...
Or still a possible faulty pressure sensor ?
 
Grayedout said:
Or still a possible faulty pressure sensor ?
Click to expand...
if you can get cold air out of the vents by using the "wire in relay pin 2" method then yes, otherwise no.
 
Grayedout said:
You mean pressing AC button and using touchscreen to turn it on and off?
Click to expand...
that's correct

before you put the wire from relay pin 2 to battery positive, make sure that you go into that "manual" system, then on the screen press the A/C ON, set the blowers to max, and set the direction to straight out (into your face LOL). With target temperature set to LO, this will give the quickest time for you to feel cold air from the evaporator. Then connect the wire, and if you do feel cold air, you know that the compressor is working and that there is enough gas in the system. But do not leave it like this otherwise the pressure will eventually build up until gas is blown out of the pressure-relief on the compressor - first time that I did this (several years ago) I left it like that for about 3 minutes and when the pressure-relief goes, it makes an extremely loud noise, and I immediately knew why, so I pulled the wire out. The compressor was not damaged and the aircon continued to work ok (there was nothing wrong with it, I was just messing about). All you are doing is bypassing the control system to check if the compressor can compress the gas. If no cold air blows, then there is no point suspecting any issues with the control system or sensors, because the compressor is faulty or there is still not enough gas.
 
Grayedout said:
A good 30 seconds with pin 2 live and no change in air temperature felt in the car and change in the 05 temperature on the dash!
Click to expand...
good thinking with using the diagnostic on "sensor" 05 ;)

that suggests a faulty compressor, or a leak, possibly even a leak in the seals in the compressor internals.
 
So does that process bypass the pressure check within the system that would stop it running? If not then would a dodgy low reading pressure sensor still stop it from kicking in?

Going to go back to the company that gassed it and see if they can measure the pressure independently with the system running.
 
The reason why the evaporator does not get cold is because either the compressor is not compressing the gas, or there is not enough gas in the system (despite the system having been re-gassed). What actually covers both possibilities, is a compressor that leaks gas out of the seals in the compressor (there are seals on the shaft). Thus, whatever causes the compressor to run (the wire, or the system), the evaporator will never get cold.

A faulty pressure sensor is a common fault on the diesel (read through "diagnosing aircon problems" and you'll see it comes up several times), the reason for that is because of where it is placed (on the 8th gen, they placed it behind the bumper). But until the compressor is fixed, the evaporator can never go cold, whether by using the wire to run the compressor, or relying on the system to run the compressor.
 
Brian, Can you or anybody have a look at your diagnostics and tell me what your air con pressure (sensor 10) is running at? Mine rages between 04 & 07 dependent on the ambient temperature.

Also if there was low pressure in the system and the pressure sensor was staying open circuit then what would this lock out? The clutch actuation? If so then as my clutch is kicking in then I have to ***ume the pressure sensor is happy.
 
Had mine refilled and cleaned at ats today. Its ice cold again. Oil was virtually empty they said.
 
f2raf said:
Had mine refilled and cleaned at ats today. Its ice cold again. Oil was virtually empty they said.
Click to expand...
you should be able to see the difference it makes to the sensors on the diagnostic system ;)

you will also now be able to help Graham - (see my next post)
 
Grayedout said:
Brian, Can you or anybody have a look at your diagnostics and tell me what your air con pressure (sensor 10) is running at? Mine rages between 04 & 07 dependent on the ambient temperature.

Also if there was low pressure in the system and the pressure sensor was staying open circuit then what would this lock out? The clutch actuation? If so then as my clutch is kicking in then I have to ***ume the pressure sensor is happy.
Click to expand...
Unfortunately my car is the 2.4 petrol, and there is no "sensor" 10 on the diagnostic system in the Accord petrol cars.
So only someone with a working aircon on an Accord diesel car can take the readings on the diagnostic (preferably with A/C OFF before engine is first started, A/C OFF when engine is running, A/C ON when engine is running, then A/C OFF again when engine is still running).

The reason for no "sensor" 10 on the Accord petrol cars is that the system on those cars is a lot simpler than on the Accord diesel car, in particular the pressure sensor on the petrol cars is a switch, whereas it's an actual pressure sensor on the diesel car. This is because the system on the diesel runs as a heat pump in cold weather, making the evaporator into a heat source, and the control system needs to monitor the pressure when the evaporator is being used as a heat source.

This is the system diagram of the system on Accord diesel (click to enlarge)

CW3_aircon_sys_desc.jpg


The pressure sensor measures the pressure at the output of the compressor (input to the condenser). As stated in the diagram, the compressor runs when the gas pressure at this point is between 0.2 MPa and 3.1 MPa. With the pressure above 1.6 MPa the system puts both fans to high speed.

Note that in #12 I said that 1 MPa = 1 Bar, but in fact 0.1 MPa = 1 Bar
I also said that normal operating range is 10 to 15 Bar, but it can be over 30 Bar (3 MPa).

The ESM says that "sensor" 10 is in MPa but I doubt if it is, it's probably in Bar, so "sensor" 10 should read between 10 to 30, and 6 or 7 indicates that there is some pressure out of the compressor, but not enough.




Anyway, your suggestion to get the diagnostic readings from another diesel car is a good idea. As I say, it needs to be an Accord diesel car, preferably with A/C OFF before engine is first started, with A/C OFF when engine is running, then with A/C ON when engine is running, then A/C OFF again when engine is still running.
 
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