HVAC Aircon pump not starting

Discussion in '7th Generation (2003-2008) [Acura TSX]' started by tonygw, Monday 12th Sep, 2016.

  1. tonygw Valued Contributor ★ ★ ★ ☆ ☆

    Hi Guys

    I recently had the condenser replaced on my 2004 accord 2.4 and the system regassed. All was working great. Until yesterday, switched on the aircon and nothing. The aircon pump didn't kick into life and the fans didn't start. I noticed there was a leak from the connection to the top of the condenser as I can see the green liquid escaping slowly. But the system still showing some gas in the glass viewing window. But the pump used to kick in even when the system was empty. (I didn't run it empty for long!!)

    I checked the fuse and two relays under the bonnet in the fuse box, they all seemed good. (I energized the relays with a battery and checked the make/break contacts)

    Is there any other relays anywhere? What else could it be? I am not sure what else I can check. I'm hoping the pump hasn't failed as then its game over..
     
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  2. Ichiban Founder Staff Team

    England CJ Leeds
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    Failed compressor clutch?
     
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  3. Zebster Expert Advisor ★ ★ ★ ★ ★

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    I think it needs to go back to have the leak repaired. Probably needs another regas.
     
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  4. tonygw Valued Contributor ★ ★ ★ ☆ ☆

    Yeah its going back on saturday. But im hoping it isnt anything to serious stopping the compressor from switching on. If it is then ill have to live without aircon.
     
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  5. Beefy Expert Advisor ★ ★ ★ ★ ★

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    A/C compressor won't run with no gas. It's most likely that leak
     
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  6. tonygw Valued Contributor ★ ★ ★ ☆ ☆

    Ah right thanks. I do hope thats all it is :Smile:
     
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  7. nauest Premium Member Club Supporter

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    What version is your HVAC system? Its possible to put it into Diagnostic mode and it will show you exactly the fault that is preventing the start up of the A/C. I recently diagnosed a faulty Pressure Sensor in my sytem as stopping my A/C from running at all (With gas in) Although your pressure being low could also cause it. I will let you know the Diagnostic procedure if you need.

    It is possible to read off the exact pressure in the A/C system off the HVAC screen on the Diesel models, not sure if yours has that function.
     
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  8. Ichiban Founder Staff Team

    England CJ Leeds
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    Any updates on this chaps?
     
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  9. jimjams Expert Advisor ★ ★ ★ ★ ★

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    The OP's car is one of the 7th Generation petrol Accords, and the system in the petrol Accords is much simpler than in the diesel Accord, in particular the pressure sensor in the petrol Accord is simply a switch that is not monitored by the A/C controller (because the switch is in series with the output on/off signal from the A/C controller to the engine ECU)

    There is the possibility that the electric clutch in the compressor might need replacing (this can be bought separately from Honda).
    You can check it without the key in the ignition, by removing the compressor clutch relay and running a thin wire from pin 2 (of the relay socket) to battery +ve, you should hear a "clunk" when the compressor clutch is energised. You can also run the engine with this wire in place, but DO NOT leave the wire in place with engine running for more than 30 seconds, and wait 2 minutes before doing it again.

    pin-out of the compressor clutch relay

    relay_pinout.

    But more likely, it seems that there is a leak in the piping in the OP's car, and the compressor will not run when there is no gas in the system (the pressure switch on the petrol Accord opens when the gas pressure has reached operating pressure, and AFAIK it also opens when the pressure is almost zero). When the pressure switch is open, the engine ECU will never turn on the compressor clutch relay, no matter what action the A/C controller has decided from the other sensors.
     
    Last edited: Thursday 6th Oct, 2016
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  10. nauest Premium Member Club Supporter

    Netherlands Ned Texel
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    Just a quick note, if you do manually start the compressor clutch, you may cause a Engine error code to be stored which will need to be cleared with an OBD II device. This was the case on my car.
     
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  11. jimjams Expert Advisor ★ ★ ★ ★ ★

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    this can happen on the diesel Accord (brings on the glow-plug light for some odd reason) but does not happen on the petrol Accords
     
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  12. nauest Premium Member Club Supporter

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    Make sense. From what I have seen of the wiring, the Deisel HVAC is more complex for some reason. The Glow Plug light is just a standard indication that there is an error code in the vehicle memory (Diesel only). The code in this case relates to faulty Radiator Fan Relay Circuit which is related to the Aircon system.
     
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  13. jimjams Expert Advisor ★ ★ ★ ★ ★

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    The piping is more complex too. The reason is that the diesel engine takes longer to warm up (bigger thermal mass) and when the ambient temperature is below 5C and the engine temperature is below 75C, there is a "magnet valve" which is operated by the A/C controller to make the evaporator turn from heat sink to heat source i.e into a quasi condenser. I suspect that that is why the pressure sensor is a "continuous" device and not a switch.
     
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  14. nauest Premium Member Club Supporter

    Netherlands Ned Texel
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    Ah thats what it is! its a smart feature too, gets your windscreen clear in the morning!
     
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