February 12, 2007

Prado Aircon Fix

Getting the air conditioner to work properly

My car is a 2003 Landcruiser Prado, GX turbo diesel model. I had the same air conditioner problem as many others. My air con compressor would constantly cut out, every 20 seconds or so. The air could be felt getting warmer whilst the compressor was off, and then cool again. It was never really cold. Toyota initially said that it was ok, but eventually relented and replaced the thermistor (a sort of temperature sender, it’s a temperature controlled resistor) under warranty; it was actually a bit better, but still not nearly good enough.

I heard of the theory to fix it for good, and gave it a go. The idea is the thermistor is too close to the evaporator, and turns off the compressor just as it’s getting cold, so I moved it away about 13mm. Results were ok but still not perfect. I bent and re-bent the plastic holder, settling on a bend of about 10mm and the results are good. The car drips underneath when running on humid days as it should, on high the compressor rarely shuts off (but does), and the air blast was at 6.5 to 8.6 degrees at the outlet, on fresh/high fan on a 35 degree day. On the lowest fan setting the compressor still cuts in and out, but I presume that’s unavoidable. If the bracket is too close it cuts out too much, bend it too far out and the evaporator freezes up. It’s a delicate thing getting the balance right. But mine is pretty good, I’m happy with it as is, it’s a shame I had to do all this though, it would have been nice if Toyota had done the work.

I intend this as an ongoing project, so feel free to refine this if you can improve on it. I am not an aircon mechanic and just worked this out for myself, so try at your own risk. Let me know how you get on, perhaps you can improve on this setup, it seems to be as good as I can get it.

STEPS:

· At this point it’s worth mentioning that there is an airbag in front of you which can kill you! If you’re not confident and even if you are; disconnect the negative lead of the battery and wait 10 minutes.

· Remove the tray under the glove box, 1 screw and then pop it down and out.

· Open the glovebox, grab the cap at the end of the string on the righthand side and pull it towards you and off. Let it go.

· Squeeze in the sides of the glovebox and pull it off and out.

· Now the trim above the glovebox comes off too, pop it straight off.

· Take out 5 screws and pop off the glovebox frame. Just let it hang on the wires if you can work around it, it’s easiest to remove the plug from the glove box light. The yellow wires are for the airbag, when I tried to unclip them I broke a tiny plastic tang. Best leave them alone.

· Pull off the short airconditioner duct, it is pointing downwards and it’s about 300mm long. Pull it straight off.

This is what you should see, looking at the center:

Reach in and pull/thread out the green cable (thermistor) and the plastic frame it is supported on and clipped into, pull on the holder and not the wire. Gently unthread the cable from the plastic holder. This is was we are going to bend.

I took mine down the shed and used a heat gun to slowly heat up the holder, and gently bent it to look like the photo below.

Try and get it as close to this as you can, the paper (as a guide) is 8mm ruled feint foolscap. It was straight to start with.

Reassembly is the reverse of the above. Make sure the cable is properly clipped into the holder. The glovebox dampener string is a bugger to get back on, just be patient. Reach in and pull the string out more than you need, slip it over the pin on the glovebox and ease it into the slot. It usually takes a few goes to get it on.

In the picture you may also note that the fat end of my holder is a bit beat-up, I presume this to be the work of the apprentice with pointy nose pliers who first tried to fix it. Good luck, it’s worth the effort to have a better air conditioner.

Window Problems: If you haven’t come across this before whenever the battery is disconnected the power windows need to be reset. Go to each door individually, wind down half way and stop. Wind up to the top and keep holding the button for 2 or 3 seconds.