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View Full Version : TB 42 Aircon airflow reducing - I think icing up



Silver
27th November 2011, 09:39 PM
G'day,

The aircon in the old Mav ain't what it used to be. The airflow reduces on trips. I have learned to turn off the aircon compressor, and leave the fan running - once the ice melts, the air becomes warm, the airflow picks up, and I turn the compressor back on, ie push the aircon button. the cycle then continues over an hour or so - maybe more?

Any suggestions? (yeah, yeah, buy a GU I know :icon_bonk:)

YNOT
27th November 2011, 09:54 PM
When the airflow slows down pull over and have a look under the bonnet. If the A/c pipes are iced up then you know you're on the right track.

Tony

Yendor
27th November 2011, 10:19 PM
It sounds like it is freezing up.

You can normally hear the clicking noise of the thermostat cutting in and out coming from behind the glovebox on the lower RHS. If the thermostat is not turning off this can cause freezing up.

They are adjustable but this should only be done with the aid of a good quality temperature gauge, yours could also be faulty and may need replacing.

Your evaporator could also be full of cr#p like leaves and dirt that doesn't help the operation of the AC system.

From memory you can see the end of the evaporator on the GQs (just under the glovebox) if it is freezing up you should be able to see it turn into a block of ice.

Silver
27th November 2011, 10:29 PM
Thanks Ynot and Yendor!!

A good excuse to go on another trip on a hot day so as to check for the symptoms each of you list.

I've not noticed the sound of the thermostat clicking on and off, but then again the Mav isn't the quietest of environments and my hearing isn't what it once was....... but now I shall look, listen and learn!

Thanks again fellas.

Rick

Killametre
27th November 2011, 11:04 PM
If it improves once you turn it off for a bit it sounds like you are on the right track, Timing again I just changed mine on the weekend as it had very poor airflow all the time, on mine '92 if you remove the glovebox and look straight in there is a plug going into a piece of plastic on the evap case (this is fan speed resistor) if you unscrew it 2screws and look in with a torch you can determine how blocked up it is before you even add the ice possibility. mine has an electronic t/stat as opposed to the old school capilary electric type and i doubt there would be any audible indication in the cab if it is functioning. generaly speaking in Queensland humidity a blocked (with dust /lint)evap will be more likely to freeze up even with a good t/stat. You also would not know how well the t/stat is positioned untill removal as it is on the sid you cant see in situ, some people are a bit rough when replacing evaporaters so if it has ever been done before it may be dislodged. mine was choca block with lint I slipped a new one in and now she blows!
Cheers Andrew

Killametre
27th November 2011, 11:25 PM
having said that there were numerous a/c fitment possibilities in the GQ range by the look of evap and comp listings in the cataloge so the fan resistor and t/stat may be located slightly different. mine is a japan fit system as opposed to a local fit

Silver
9th December 2011, 07:16 PM
Got Silver back from the auto leccie, 45 mins labour and $80 for an adjustable thermostat to replace the cactus original.

Apparently the evaporator was clean.

So, help above spot on, thanks heaps!!

Yendor
10th December 2011, 09:35 AM
Glad it was an easy fix and wasn't too painful for the old wallet.

Killametre
10th December 2011, 08:44 PM
Good to hear you got it sorted

gu radelaide
21st December 2011, 08:21 AM
i just used 2 run the temp a bit hotter in the gq it stopped it icing up

Silver
21st December 2011, 11:07 PM
thanks gu radelaide. Do you mean the aircon thermostat? I think previously it was non adjustable, but the new one is - and it might be a bit warmer. I'm going to ask them to have another look at it, or show me how, after the Christmas rush

gu radelaide
22nd December 2011, 09:46 PM
u can do that, i meant the blue to red heater adjuster on your dash just slide it to heat bout a 1/4 and occasional blast on cold