A/C Electronics

[sasha007k Lurker Find all posts View Profile Close sasha007k]

Hi all,

Recently, I have had an issue with my air conditioning not working.

I have done a bit of work and found that the compressor's magnetic clutch was not activating. I then traced the problem to the A/C amplifier which was not sending a signal to the magnetic clutch relay.

I now have a bit of a dilemma. I am unsure as to whether the issue is that the A/C amplifier is fried or whether it is getting information from a sensor telling it not to activate the magnetic clutch.

With that in mind, could someone shed some light on any of the following:

1. Is there a way to test whether or not the A/C amplifier is fried?
2. What input sensors does the A/C amplifier rely on and where are these sensors located?
3. If I completely bypass the A/C amplifier and have the cabin A/C button linked directly to the magnetic clutch relay, will there be any long-term detriments to my car?

I have a KZJ120R model. Thanks in advance for your advise.

[topic97 Senior Member Find all posts View Profile Close topic97]

Most likely it wont be the amplifier, it will be the thermistor(sensor) that is in the evaporator that is causing your dramas.
If you can get your hands on a replacement, you can plug it in to the amp and if that's what the issue is, it'll engage the compressor.

And I wouldn't bypass it.
Number one you will be switching it on and off constantly - as they cycle quite rapidly, usually 30 seconds ish depending on the climate.
But number two, the thermistor senses freezing of the evaporator, and if you bypass it you will have no way of knowing if the evaporator has iced up & it can go bang if it freezes.

[sasha007k Lurker Find all posts View Profile Close sasha007k]

Thanks for the advice topic97.

I will try this out and see if it works.

Will post photos and instructions for people's future reference.

[sasha007k Lurker Find all posts View Profile Close sasha007k]

Hi all,

I have replaced the thermistor but this did not seem to be the cause of the problem.

Upon doing some further investigating, I found that for some reason the Pressure switch was not getting a +12V signal from the IG1 No2 circuit. This seems like a weird one because if I apply +12V directly to the grey/blue wire, the A/C starts working beautifully.

In order to fix this problem, I may just install a new cable linking the IG1 No2 circuit to the pressure switch, I am however open to suggestions (see below wiring diagram).