Thread: TD5 110 - Air conditioning not working

Hi Mellow Yellow, There should be a safety switch some where in the system, usually on the receiver drier. They generally are low/high pressure switch in one. If you short it out and the clutch cuts in then there either is a high pressure fault ( unlikely ) low pressure fault ( the gas has got out, most likely ) or the switch is faulty ( unlikley).
You will then need the AC gauges to check the pressures.
Freestyler

Thanks Freestyler.

According to the Rave manuals there is a Low/High Pressure switch in the system.

From what I can interpret from the Rave circuit diagrams it provides a closed circuit for the signal from the A/C-ECM interface (what Rave calls the "Air Conditioning Unit") when the regrigerant pressure is within operating limits.

So, as you say, if the pressure switch is faulty, or the gas pressure is out limits, then by shorting the switch out the compressor clutch and the condenser fan should cut in. If I can get at where the pressure switch connects into the Air Conditioning harness I will short it out and see what happens.

The pressure switch is not in the A/C gas lines in the engine bay which means that it must be with the evaporator up under the dash on the passenger's side of the car.

The only fly in the ointment is likely to be getting at this connection as it will be somewhere up under the dash where access is very limited - even after dropping the A/C console down away from the dash.

I think RAVE will be useless with this as I'm pretty sure the air conditioner will be an AMC (or equivalent) Australian fitment, as were the Tdi's and early TD5's.

If so it'll have a pretty basic wiring system.
Relays in the battery compartment, mechanical t/stat, pressure switch on the dryer. (I think the circuit may even be listed in the files section of the site)

As Freestyler suggested, it should just be a process of elimination with a multi-meter to see where you are losing your circuit.

[edit] To tell what A/C system you have, the Australian fitted system uses the full width moulded plastic assembly under the dash with the fan and evaporator in the passenger footwell.
The UK system is incorporated into the heater box/ventilation assembly under the bonnet.

AMC wiring diagram here Australian Land Rover Owners

mine had the same fault last week and it was the 2 wires from the ECU were toast. even when they cleared the faults it wouldnt work as the eCU wasnot talking to the air con system.

apparently it can be bypassed but as i just bought the car i insisted that it should be fixed properly...... they fixed it by putting in a brand new ECU. now it works sweet.

Cheers

Originally Posted by rick130

I think RAVE will be useless with this as I'm pretty sure the air conditioner will be an AMC (or equivalent) Australian fitment, as were the Tdi's and early TD5's.

[edit] To tell what A/C system you have, the Australian fitted system uses the full width moulded plastic assembly under the dash with the fan and evaporator in the passenger footwell.
The UK system is incorporated into the heater box/ventilation assembly under the bonnet.

Thanks Rick130.

My A/C system is definitely an add-on as it's a "full width moulded plastic assembly under the dash with the fan and evaporator in the passenger footwell." However, the relays are located in the cubby box under the driver's seat along with the ECM. The operation of the unit is also described in the owner's manual.

I guess this means that somewhere along the line Land Rover started to fit the AMC unit to the TD5 110's in the factory.

With the Rave manuals, they describe the arrangement and operation of the system correctly. The written description matches the circuit diagrams and also the actual wiring in the Defender.

The only issue I have with the manuals is they give absolutely no detail on what the A/C-ECM interface does and no detail on how the Low/High Pressure switch works.

That the A/C unit is an add-on probably explains why there is a non-Land Rover part Number on the A/C-ECM interface box and I can find no reference to it on any of the UK Land Rover parts suppliers sites that I've looked at (eg Rimmer's).

Thanks again for your help and I'll keep following a process of elimination until I find out where the problem is.

Originally Posted by Josh_WA

mine had the same fault last week and it was the 2 wires from the ECU were toast. even when they cleared the faults it wouldnt work as the eCU wasnot talking to the air con system.

apparently it can be bypassed but as i just bought the car i insisted that it should be fixed properly...... they fixed it by putting in a brand new ECU. now it works sweet.

Cheers

Thanks Josh_WA.

You'll hear the scream in WA if it turns out to be an ECM problem other than one solved by clearing a fault.

I'm expecting to get my Nanocom Evolution (courtesy of Paul P38a) tomorrow or Monday and will then clear any fault in the ECM. Hopefully it will also tell me if the ECM is receiving two signals (one from the Blower and one from the Pressure Switch) as set out in the Rave manuals.

If necessary I'll test the two wires from the A/C system to the ECM.

Good luck with it mate. I was lucky that mine was broken when I bought the car so I made the dealer fix it for me so it didn't cost me anything.

Got my Nanocom Evolution on Friday (Thank you Paul38a) and found the Outputs screen and tested the A/C clutch and the A/C condenser fan. Both started up as they should which confirmed my earlier conclusion that they weren't the problem and neither were their relays. In addition these tests confirmed that all the associated wiring was sound.

Then I went to the Faults screen and saw that there was an air conditioning faullt logged. So I immediately cleared it.

And the air conditioning then returned to life. Yes !!!

However, after playing with the Nanocom over the next two days I came to realise that there were 22 faults regularly appearing and that when I first used the Nanocom I had only seen the first of these [08-01 air conditioning fan drive over temperature (logged )]. So maybe when I first cleared the faults I cleared an additional fault or two??

I don't understand. But I don't like it when a problem "goes away" and I don't know why. My experience is that that sort of problem always comes back !

[As to the 22 faults, from what I've gleaned from the Nanocom.it TD5 downloads these can be ignored. The faults concerned are all the 8, 10 and 12 series faults. One of those "truth is stranger than fiction" things, i.e. the faults you have when you're not having a fault.]