300tdi airconditioner not working

[Ringky]

Hi All - Im after a little guidance.
Nothing happens when the aircon dial is turned and the fan turned on. I assumed it was probably just a fuse. The book said it was fuses 18 & 19, both OK but I replaced them anyway - still nothing. Im not sure if there are other fuses located elsewhere, though i did find 4 maxifuses near the heater matrix which were all fine. Are there any others associated with the AC anywhere else??
I thought id pull the switch out and check for power there, but the thing is sealed into the unit and Im not keen to pull it out unless im sure that is the issue. Any other quick elimination checks I can do before I resort to my local mechanic??
Cheers
Chris

[scanfor]

Chris, there is a low-gas cutout that may have activated.
If the system has lost its charge, then it prevents anything starting up.
Mine cracked the aluminium pipe where it goes into the aircon condenser (in front of the radiator) and I had the same fault.

[Blknight.aus]

check the connections on the 2 plugs on the elbow of the thermostat outlet

check the yellow relay down in the drivers side kick panel

pull the plug on the 3 way switch and short across it.

[jboot51]

2 fuses and 2 relays in the battery box.




1 fuses and relay for the fans and control circuit
1 fuse and relay for the compressor

[Ringky]

Thanks Dave,
the first 2 points seem straightforward, is the 3 way switch the fan control in the unit?
Chris

[Ringky]

thanks JBoot51 ill check those too

[Blknight.aus]

nope its usually on the pipe on the engine side of the vehicle in the engine bay about level with the lift pup.

the plug is on the bottom.

if you pull that plug and short it then the problem is either A, the switch or b, (and most likely) youve lost the gas.

If shorting that switch doesnt sort it then you have other problems which can be as simple as a fuse or as annoying as a blown coil in the compressor clutch, hell it can even be a bad earth.

[isuzu110]

My issue was the relay on the control board (under the passenger seat) had died. It was intermittent and responded sometimes by tapping the relay. You can read the post here (http://www.aulro.com/afvb/90-110-130-defender-county/119231-air-con-wiring-advice-needed-6.html) if you are interested

[Michael2]

I had intermittent issues with the sealed control box (in the battery compartment). I prised it open and found that the +'ve feed terminal had arced and burnt out the solder joint. I resoldered, but the pin had also destroyed the plug due to heat, so I soldered extension wires and single plugs and plugged it back into the loom. I had to do this as I was travelling through the Kimberley and couldn't get parts, the original parts aren't available, but better generic after market control boxes are available from automotive AC places for about $50.

[rick130]

check the connections on the 2 plugs on the elbow of the thermostat outlet



Except that doesn't exist on a Defender Tdi !

Easiest place to start is the compressor clutch connection and work backwards.
Just pop the bullet terminal apart and check for power, then work back through the pressure switch, etc.

[uninformed]

just pull the whole thing out and leave the vents open :D the acerage that thing takes up in the cab is ridiculous!

[Presto]

Hey Chris,

I've just been through this with my 1994 Def 110 and found the wiring diagram posted in this thread very useful for problem solving:

http://www.aulro.com/afvb/90-110-130-defender-county/119231-air-con-wiring-advice-needed-2.html

That's the same link posted by Isuzu110 above, but I wanted to make it more obvious.

Firstly, check the relay on the far right (under passenger seat as you look from passenger door). The white wire should show 12v when ignition is on, and the red wire the same (this would confirm that relay/fuse is ok). This red wire supplies power to the blower switch and most of the system from there.
Next check the red wire going into the Thermo-amp (the box on the left) under the passenger seat, which should be showing 12v with ignition and blower switch on.
Hope I'm not teaching you to suck egg's, but I'm sure you get the idea.....

The problem I had was the Thermo-amp itself, which was not activating the pressure switch, and therefore the clutch. However, in my case the blower was working, but I had lost pressure in the system due to a clamp rubbing through one of the ac rigid pipes (drivers side corner near the firewall). After repairing the pipe and getting it re-gassed, I have made a temporary fix of bridging the thermo-amp red wire to the black wire going to the pressure switch (effectively by-passing the thermo-amp, thermo switch, & probe). I do plan on replacing the Thermo-amp with a 3rd party variable thermostat, but for now I just have to be careful it doesn't ice up as the compressor is always pumping when the blower is on! :p ......the things I'll do the keep the misses happy! ........ :mad:

[Ringky]

Presto that was really handy (eventually) - in typical LR fashion another issue popped up before i had a chance to have a good look at the AC, the vacuum pump died then the booster then the new vacuum pump. Anyway thats sorted now.
I went through Prestos steps, turns out theres no power getting to the relay from the ignition (the white wire). I jumped some power across from the battery and the fan and compressor both work (and cold with engine running)

Is there an easy way to trace the ignition wire - as it doesnt appear to go through the main fusebox (or does it??) not a white wire that i can see.
I could just run another wire from another ignition source BUT id rather sort the issue properly. Any help would be much appreciated.

Thanks
Ringky

[Presto]

I'm glad my waffle helped someone!
Unfortunately my defender isn't with me at the moment to check the white wire route, but as I didn't have any issue with the ignition pick up, I never really looked at that, and don't think it will be easy to follow/trace anyway. I'd suggest it must go through the main fuse box!?
Will try and check later in the week.

An update on my system....

I pretty much hit the icing problem on the first day out, so solved the issues using one of these, which I purchased from Ashdown Ingram.

Product » PT. Indotek Perkasa Jaya (http://www.indotek-bpn.com/product.php?category=rzdrzytz&product=TSX1012)

This is a very simple mechanical variable thermostat, which I used along with a relay, to bypass the Thermo amp, thermo switch, and probe in the standard installation.
Referring to the diagram I posted above, I used the two yellow wires from the old thermo switch (at the blower switch /dash end) and mounted the TSX1012 next to the blower switch with the probe extended into the air flow. Then in the battery box I connected a relay fed from the Red return wire from the blower switch, activated by the TSX1012 (one of the yellow wires). The output from the relay connected to the black wire (pressure switch and clutch).
Since I completed this mod, the aircon has been working very well :)

Total cost for the fix (TSX1012 + Relay) was about $35.

Hope this helps someone!

[86mud]

I really need to fix mine....I have put up with it for too long!

Mine freezes up after about 40 minutes of run time. First sign is ice spitting out of the vents, then the air flow just starts to slow down even though the fan is not changed rpm. I turn it off and after about 30 minutes, it is right to go...that is after about 4 litres of water pours from the drain pipe.

I assume this is what you faced Grant?

Thanks

[Presto]

Yep, exact same problem I had Andrew! Your compressor must be wired to continually pump!?