General Aircon no function before or after service.

Discussion in '7th Generation (2003-2008) [Acura TSX]' started by blackbeard, Saturday 15th Aug, 2015.

  1. blackbeard Club Member ★ ☆ ☆ ☆ ☆

    England England Kent
    Good evening gents.

    Got round to trying the air con which had never produced cold air.

    Had my air con serviced at Mr Clutch today full evac ,pressure leak test, anti bacterial clean , regas to 500 grams (their max ).
    Their rule is if any leaks at all they will not fill, they said it was gas tight so their part done, which I except.

    Got a call to say they could not get it to function , so I said i would look at it my self, they did however offer to extract and refill for me should such repairs require gas extraction.

    Got home and discovered the compressor clutch does not engage, nor the condenser fan on activating the air con from the dash.
    Checked both fans with 12v direct, both function.
    Under dash fuse 30 intact
    Under bonnet fuse 9 intact

    Tested both fan relays cleaned contacts , both ok.
    fed 12v from air con clutch solenoid relay terminal, solenoid clicks on compressor.
    Fed 12v from condenser fan relay terminal, fan engaged.

    Removed solenoid clutch outer plate, de rusted both interfaces with 600 grit wet and dry paper, removed 2 of the 3 shims and left the thickest in place reinstalled to force compressor, it engaged delivered colder air to cabin, ran for 30 seconds only.
    Reassembled all shims and reinstalled as was.

    On trust that Mr Clutch have done as they have said, and the fluid volumes and pressure are correct :-

    I am anticipating the pressure switch activates the compressor clutch and fan at the same time on activating the dash aircon button, as both do not function. The cabin fans ramp up anticipating colder air therefore , am I correct in assuming that this pressure sensor will be my faulty component stopping the air con from working ?

    A pointer to it location would be appreciated, bumper off job perhaps ? I know I won't be so lucky for it to be self sealing on removal, so am anticipating having the gas re extracted to effect its replacement.
  2. jimjams Guest

    You didn't say that you had tested the compressor clutch relay as well. If not, since you've tested both fan relays and the condenser fan runs, swap the condenser fan relay with the compressor clutch relay. If the condenser fan does not run, then you've found the fault. If it does run then, as you say, the problem might be to do with the pressure sensor.

    If your car is not the diesel version, the pressure sensor is a simple switch, and you can test the system by shorting the two terminal pins in the connector that plugs onto the pressure switch (it's down behind the headlights on the driver's side). If this brings the system on, remove the short immediately. Then take the car back to Mr Clutch and ask them to change the pressure switch.

    If your car is the diesel version, then the pressure sensor is not a switch, it's a true analogue sensor. It's down in front of the condenser. Since there is no way to fool the system, best thing is to just take a punt and get it changed..

    If you fancy changing a pressure sensor yourself, go to Mr Clutch, ask them to evacuate the system, do the work, then take it back and ask them to re-fill it.
    blackbeard likes this.
  3. blackbeard Club Member ★ ☆ ☆ ☆ ☆

    England England Kent
    I tested the compressor clutch relay and as far as I could tell it was operational, going to replace the fan relays first found them cheap enough.
  4. jimjams Guest

    I'm a bit confused by that LOL

    Anyway, the two fan relays and the compressor clutch relay are all inter-changeable, originally grey Denso

    So if you swap them round 3 times and both fans run at each swap, then you've ruled out the relays.

    btw, is the car the diesel version, or a petrol version
  5. blackbeard Club Member ★ ☆ ☆ ☆ ☆

    England England Kent

    I'm a bit confused by that too LOL

    It's a diesel and only two of the relays are interchangeable in the main fuse board, the third, in the secondary fuse box is larger and five pin, as opposed to four.

    I have no idea which pins to test this relay with without risking damaging it, but chances are it's mullered anyway as the fan does not come on.

    All the relays I have tested are related to the condenser/ or radiator fans , as neither has actually run, either for air con or the radiator for cooling, I went through them all, two greys on the main board, one black in the secondary board . I have damaged one of the black type so that is why I mentioned buying cheap replacements, sorry to confuse.
  6. blackbeard Club Member ★ ☆ ☆ ☆ ☆

    England England Kent
    Just to clarify on my 04 diesel accord the condenser fan relay is in the secondary fuse box



    Top left larger in Grey. It's a five pin relay, as opposed to it's neighbours who are four pin.


    Part no 39704- S10- 0003

    This is how it's marked. On the Lings parts diagram this is shown located bottom left, to add to the confusion.

    This is its five pin socket in the secondary fuseboard.


    This is the main fuse board, the two Grey Denso relays are :- top row in between the two turquoise coloured relays Compressor clutch relay.

    Bottom row just off centre 2nd condenser fan relay.

    The blanking plate bottom row far right, is where I suspect the petrol versions second fan relay would live.

    So for relay testing purposes on the diesel , only the two relays in the main fuse board can be swapped over.
    - - - Updated - - -
    Ps anyone interested in obtaining after market relays :-

    Thanks to Zebster for link

    Or pressure relief valve :-

  7. jimjams Guest

    I was thinking of the petrol car: the relay for the radiator is in that empty slot in your picture, and it is interchangeable with the other two Denso relays

    Yes on the diesel, the relay for the radiator is not in the main fuse/relay box in the engine compartment, but it's in that extra box. The relay with 5 prongs is a "fan control relay", also in the smaller box with the radiator relay. The "fan control relay" controls how the two fans come on, see note below about the temperature switches.

    The two grey Denso's in your diesel car, one for the condenser fan, one for the compressor clutch, are interchangeable. so they can be swapped over as a test, but see next.

    Because the diesel engine takes a long time to warm up, it could be a long time before the main radiator fan comes on. There are two temperature switches on the radiator on the diesel. The first one comes on at 93 C, which will pull on both fans in series. The other one comes on at 99 C, which throws the "fan control relay", which pulls on both fans electrically in parallel.

    As far as I can make out, the A/C system in the diesel will pull on the fans in series in some conditions, and in parallel in other conditions, probably depending on whether the A/C gas is running in the normal direction, or the reverse direction (a peculiar way of heating the car in very cold weather while the engine is cold).

    But in general, the A/C will work even if the radiator fan relays are duff. It is only the compressor clutch relay that needs to work for the pipes to get cold. If the compressor clutch relay is tested ok with a meter, and the system is still not working, then obviously the relay is not being triggered. In the petrol car, as I say, the pressure sensor is a switch and this is easy to over-ride as a test, but in the diesel car there is no way to simulate, so substitution is the only way to test.

    Apart from a faulty compressor clutch relay, or a faulty pressure sensor, the only other thing that can stop the system from attempting to trigger the compressor clutch is the "relay control module".

    Attached Files:

    blackbeard and SpeedyGee like this.
  8. blackbeard Club Member ★ ☆ ☆ ☆ ☆

    England England Kent
    Thanks for the description of the fan operation.
    I'd assumed looking at the extra pin outs on the controller that it had a multi purpose function, I'm fairly certain it is this that is goosed .The Honda mechanic today insisted that he had not changed many pressure switches in his time at Honda on the Accord, I've not heard the rad fan come on at all, but suspect I have a stuck open thermostat as well, but that's another story. for another day.
  9. blackbeard Club Member ★ ☆ ☆ ☆ ☆

    England England Kent
    Replaced all fan, and compressor clutch relays.
    Today had Mr Clutch evacuate and store the AC fluid, while I installed a new pressure sensor, and now have a functioning air con system.
    See links below for where I bought these items from :-

    AC pressure sensor
    5 pin relay
    4 pin relay same supplier
    jimjams likes this.