Our V6 TR magna has developed some problems with the aircon.

I have checked and double checked everything (fuses, relays etc) and everything is in good order.

The problem started out like this:
Bought the car 3 years ago and aircon worked like a trooper. it actually got that cold on a hot day that the air ducts seemed to freeze up and we would have to turn it off for about 5-10 mins and have the windows down.

After about 2-3mths some electrical gremlins got into the car and the headlights would stay on even after they were switched off, and a few other small electrical gremlins. Ended up with a burnt out alternator and fuse box which a local auto elec repaired and replaced one relay from inside the box and mounted it externally. Im not certain of what happened or what was repaired as I was working away at teh time and didnt get an invoice.

Aircon still worked well,

Now, a couple of years down the track, there was some more gremlins happening and the aircon stopped working. I replaced the relay in the box in the engine bay and it worked again for about 6-7 weeks but it has now stopped working all together.

I have checked everything and there appears to be no power coming through the wire to the compressor clutch.
Fuses are all good, relay is good too (tested in our other TS V6).

I can remove the relay and run a wire direct from the + side of the battery to the terminal where the relay sits and the radiator fans kick in as they would do when the aircon was switched on, but the compressor clutch doesnt come on at all.


Could this just be a case of the compressor clutch has shat itself or something else??

It sort of appears that the aircon switch in the dash isnt working but I cant be certain. The radiator fans dont turn on though so that sort of indicated to me that the switch may be faulty.


This is driving me crazy (not just the problem but also the missus getting on my back to fix it............) I have been off work for 4mths with blood clots so funds are really short and cant justify taking it to the auto elec.

Regards,
Andrew
Bundaberg QLD

You could try looking for the PDF files for Mitsi Workshop manuals - they may now be stashed in the 3rd Gen forum,. even tho there are some 2nd Gen files linked as well.

You want a thread "Sticky" called "workshop manuals" and look for the links appropriate to your car.

Unfortunately the PDFs for 2nd gen are a lot less user-friendly than the 3rd gen ones = instead of being able to jump about, you may have to page through a one big document, for instance. Anyway, there may be a troubleshooting job-flow for air-con problems, and details of simple tests you can do to trace faults and eliminate possible causes. Even to have the wiring diagram may be of great help to you.

These files are Mitsi stuff mostly - what a dealer service dept would consult. Again, in some cases the 2nd gen info may be US sourced, but general approach and many details will be similar.

Another option may be to find a wreck and see if the air-con clutch can be dismantled on your series - if a body shell has engine out and air-con intact -it'd be a hell of a lot easier to "get your bearings" before possibly attempting stuff on your car in impossibly tight spaces!!

Good luck - hopefully someone in here may have direct experience...... our family jumped from 1st gens to 3rd gens largely, altho we are about to put my niece on teh road in an Assstron TR Exec.

If all the fuses and relays (inside car and under the bonnet)check out OK then check the receiver drier unit HP/LP switch. The receiver drier unit is a vertically mounted aluminium cylinder with a liquid refrigerant sight glass located on top. On TJ-TW models this is mounted near the front of the car- adjacent & below the battery and has a HP (high pressure) LP (low pressure) cutout switch on top of it which the A/C wiring plugs onto. If the system has a refrigerant leak the systems refrigerant pressure will drop and the LP contacts will open and prevent the compressor from cutting in (protects the compressor). If its the LP switch causing the problem then the switch will remain open until the system is recharged. Recharging can only be done after the leak has been located and rectified. If the system has excessive pressure from say being overcharged with refrigerant, has a capillary tube blockage, defective Tx valve, the condensor has a cooling problem or the fans don't kick in then the refrigerant system pressure on the high pressure side will increase until the HP cutout operates and cuts out the compressor (protects the compressor, condensor and HP piping). Once the pressure drops the system resets and the compressor will kick in until it trips on the HP switch again. To check if it's an LP switching problem you need to electrically by-pass the HP/LP switch (don't remove the switch from the drier unit), start the engine and turn the A/C on to see if the compressor clutches in. If the compressor cuts in you have a refrigerant system leak which needs to be repaired. By-passing the HP/LP switch is for fault finding only and bypass wiring should be disconnected immediately the results are known.

Cheers

Thanks magna diver for your really descriptive trouble shooting guide.

Will certainly look into that tomorrow :)

Hope that wasn't too confusing.

Cheers

Naah, its easy enough to understand when reading :) I will see tomorrow though lol

Well I managed to get to check the HPLP switch and it isnt the problem. Im at a loss. The fusebox layout is slightly different to that of my TS-V6, but I have tried everything, replaced all the relays with those from the TS, and then checked the HP/LP by bypassing it.

It did have some wiring issues in the engine bay electrical box but had them repaired by the local auto elec, not certain of what was done but they replaced the alternator and now have an external relay on the engine bay electrics box
It seems to me that it must be either of 2 things: The aircon clutch itself, or the AC switch in the dash.

Any ideas on where to look now???

To check the clutch to see if it's energising try the following with the engine switched off. Unplug the power lead at the compressor body (single pin brown connection plug with 1 x green wire with a black trace) and run a wire direct from the battery positive terminal to the plug terminal pin. This will put power direct to the clutch via the compressor temp sensor (wired in series so power must run through this to reach the clutch) and you will feel the clutch engage/disenage etc as you take power on & off. If the clutch doesnt engage you either have a problem with the wiring from the brown plug, the temp sensor or the clutch unit itself.

Note: Plug, wiring colors and comp temp sensor info is based on TJ-TW models

Cheers
Peter

On the second gen, there were problems with the plug that goes from the loom to the com itself

When you are having this issue, does your aircon fan come on but the aircond comp does, not. If the fans are not coming on then your issue is not your clutch, it is electrical

The first thing you should do is remove all those metal top relays and grab a handful of first gen relays and use them, they last longer and solve those problems you have had in the past

It is a concern that some of your wiring has been butchered, hopefully this is not the issue

Also, if your gas pressure is low, the air con will NOT kick in either, may be an idea to take to an aircon specialist and get them to check as they can check the line pressure, bridging the switch will not make the aircon kick in

To check the clutch to see if it's energising try the following with the engine switched off. Unplug the power lead at the compressor body (single pin brown connection plug with 1 x green wire with a black trace) and run a wire direct from the battery positive terminal to the plug terminal pin. This will put power direct to the clutch via the compressor temp sensor (wired in series so power must run through this to reach the clutch) and you will feel the clutch engage/disenage etc as you take power on & off. If the clutch doesnt engage you either have a problem with the wiring from the brown plug, the temp sensor or the clutch unit itself.

Note: Plug, wiring colors and comp temp sensor info is based on TJ-TW models

Cheers
Peter

I checked the compressor clutch by the above method and I can hear it clunking in and out when I connect power and disconnect it.





On the second gen, there were problems with the plug that goes from the loom to the com itself

When you are having this issue, does your aircon fan come on but the aircond comp does, not. If the fans are not coming on then your issue is not your clutch, it is electrical

The first thing you should do is remove all those metal top relays and grab a handful of first gen relays and use them, they last longer and solve those problems you have had in the past

It is a concern that some of your wiring has been butchered, hopefully this is not the issue

Also, if your gas pressure is low, the air con will NOT kick in either, may be an idea to take to an aircon specialist and get them to check as they can check the line pressure, bridging the switch will not make the aircon kick in

From what I have noticed the fans do not cut in at all when the AC switch is turned on (obviously with interior fan on)

The wiring was altered by the autoelec because Mrs had an issue where the battery went flat mysteriously (of course whilst I was working 1200km away) and it was totally flat. had the battery tested at local battery shoppe just up the road, and it was fine. They recharged it, she bought it home inserted it (good mechanical knowledge) and noticed the headlights were on slightly. Autoelec was called and said it was the elec box under bonnet, about $500 later for the new alternator and wiring bypass and it was going again no problems.

I dont think its gas related because the day it stopped working it was fine, very icy cold as usual.


I replaced all the relays with those from my TS-V6 (the good plastic ones) and still nothing, the fans come on when the engine is up to temp for them to cut in but they DO NOT come on when the AC is switched on.


Is there any way that I can test from the dash switch back to the elec box under the bonnet, or is there any other known faults with the wiring?

Have you checked the A/C thermostat ie: It may have gone to permanent open circuit due to a fault? You could try running your own wiring external of the dash & into the engine bay.

Oh and by passing the HP/LP switch on the TW allowed me to run the compressor and check it's condition after the vehicle was front ended / written off.

Cheers

how do i check the ac thermostat?

Im pretty sure now that the problem lays in either the elec box under the bonnet (near the battery) or the switch in the dash.

Everything else works individually, but what has me stumped is that when i remove the AC relay and jump wire it from the battery the radiator fans come on but not the AC compressor clutch.

Makes me think its more sinister, and from reading other threads in the past and talking to other TR/TS magna owners it seems to be a known problem for the magna elec box under the bonnet to be a problem source.

The A/C has a thermosensor mounted in the heater box ducting under the dash. Not sure exactly where its located in the ducting but it should be mounted just after the evaporator so as to measure the temperature of the air after it's been cooled. The Max Ellery 91-2005 Magna book TR-TS wiring diagram for a manual A/C system shows a red wire with a yellow trace leading from the AC control unit to the sensor and a black wire going to the earth point coming out of it.

The A/C control unit has the following wires plugged into it:

Black - goes to an earth point
Blue with a white trace - goes to the A/C switch on the dash
Red with a white trace - goes to the A/C switch on the dash
Green with a yellow trace - goes to the transmission control unit and the low condenser fan relay

Not sure where the control unit is but if you trace the wires back you'll be able to find it and check its connections.


Cheers

When your air con was working properly, was it cycling on/off as it should? You say that before it was working so well that it got too cold and you had to switch it off - that shouldn't be happening, indicates to me that the control unit was fully on at the time, with the compressor running full time, rather than cycling. I had the same problem, with it "working too well" and then "not working at all" but I got rid of the car soon after and never fixed it - but I suspect the control box was failing. It is a small box attached to the air box under the dash.