Aircon problem

[jaramart]

Hi guys My paj is a vrx model with dual zone air con. I’ve noticed that the front is only cold under 2 conditions.
1. When the rear is switched on
2. When the rear is switched on and I’m driving. It will sometimes not be very cold when at a idle.
I’ve also noticed that if it’s a hot day it just doesn’t cope.

When I got it the air con guy re-gas the unit it took .22kg of gas. But it didn’t help with the top 2 problems.

I’ve also noticed that I have 0 water draining outside at the front. Only rear.
Anyone else have this?

[spot01]

Simple things first - when was the cabin filter last changed?


Did the a/c guy measure the temperature at the front outlets?

[crojo]

Sounds like a clogged cabin filter to me too, I remember when we first changed ours out the difference was incredible


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[jaramart]

Aircon guy did the test of vents, I can’t remember what the temp was now it was cold but the rear air con was on and it was late in the day so it felt really cold.
I pulled the cabin filter out completely for a test as that was my first thought too but it didn’t make any difference

[_jp_]

Does the compressor engage when only the front AC is on?

[jaramart]

Yeah mate everything seems to be engaging. It almost feels as if the aircon has isn’t being circulated through the front evaporator unit

[jaramart]

So I did a bit more investigation. The condenser fan aircon pump are kicking into gear when I turn it on. But the idle doesn’t increase.
What should the idle be sitting on when for following situations.
1. In park or neutral no aircon on
2. As above but with the aircon on
3 in drive no aircon on
4 in drive with aircon on
Thanks guys

[erad]

"What should the idle be sitting on when for following situations.
1. In park or neutral no aircon on
2. As above but with the aircon on
3 in drive no aircon on
4 in drive with aircon on"

I don't know, but you said that the aircon works when you have the rear A/C engaged, so why not note these readings when the A/C is running - this should give you some idea as yo what to expect. You probably have climate control, so this tends to override all other ways of testing. The old days (the Good Old Days) when things were simple, you could easily check the fan speed controller. There is a resistor, and when the resistor burnt out, the A/C would not operate on anything but flat out fan speed. Try manually boosting the fan speed to max and see if you get any cooling then. If you do, the resistor bank is stuffed.

[ticky]

This might sound a bit backwards, but your aircon will get colder with a lower fan speed than a higher one. The reason is quite simple, the air is passing through the evaporator at a slower speed therefore more heat is removed from the ambient air.

Very interesting, but it doesn't solve your problem.

The air con guy you go to, is he a mechanic that services air cons or is he an Aircon /refrigeration specialist.

The reason I ask, is an air con service is dead easy if there is nothing wrong with the system. you could teach a gorilla to go it. But it gets tricky when there is a problem.

One possibility I can think of. There is a valve on the liquid line just before the evaporator. Im not sure what the Pajero uses, but it could be an Orifice or a TX Valve, it doesn't matter, they all do a similar thing. It sounds like that could be blocked. Sometimes an indication of this is the compressor will cycle very quickly.

A specialist auto air guy should be able to give you a good indication of the problem by putting his gauges on your system. different readings indicate different problems.

I used to do this for a living, but it was a long time ago and things have changed a bit since I did it.


Steve

[jaramart]

Thanks mate. Yeah I think I’ll have to go back and get him to check it out. Your correct that the air is very cold at a lower speed.