Landcruiser 80 aircon

Submitted: Tuesday, Nov 10, 2015 at 16:59
ThreadID: 130849 Views:1441 Replies:4 FollowUps:11
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Hi all

when i start up my car my aircon blows nice cold air but after about 10-15 minutes of driving the air starts blowing hot i have had the gas checked and it seems fine although the compressor does not appear to cut off like it used to

i have changed the fan clutch as it was stuffed and i thought it might not be pulling enough air through the radiators to cool down the a/c system but alas no joy

if anyone has any suggestions it would be greatly appreciated
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Reply By: Steve in Kakadu - Tuesday, Nov 10, 2015 at 17:38

Tuesday, Nov 10, 2015 at 17:38
The compressor wont cut in if the unit has no or little gas, so if the compressor is working it has gas.

However there is a sensor that cuts the A/C if the car is over heating, I can't remember where it is as I haven't owned one for a while but I am sure someone here can point you in the right direction.
AnswerID: 592563

Follow Up By: Lachlan T - Tuesday, Nov 10, 2015 at 17:54

Tuesday, Nov 10, 2015 at 17:54
thanks mate

the compressor cuts in fine as soon as you push the button but wont cut off as the a/c cycles itself
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Follow Up By: Ross M - Tuesday, Nov 10, 2015 at 18:42

Tuesday, Nov 10, 2015 at 18:42
If the system is cycling it means the compressor IS switching on and off. All cycling is done by activating a compressor. Something in the observation of the problem is not quite right.

If the compressor keeps running it points to the thermostat control (either a mechanical or electronic one) which is too far away from the air evaporator core in the dash chamber and being to far from sensing core temp, it will continue to run the compressor. That then freezes available water onto the core and although air can get through some section, the rest may be a block of ice which can't impart coolness to the air. So it effectively runs HOTTER and seems like the system isn't working, but it is. Just not as designed.

I would check if the temp sensing position is correct, maybe remove some of the ducting and clean out any crap in which builds up against the core unit.

Make sure the internal blower fan works as it should respective to switch speed position.
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Reply By: Member - ACD 1 - Tuesday, Nov 10, 2015 at 18:00

Tuesday, Nov 10, 2015 at 18:00
Hi Lachlan

I had the same thing in my 100series.

Had it regassed several times. Worked well for a month or two, then back to the workshop.

They tried changing a valve (?) which I think they called a Tx (?) valve as they thought this was they said this was the cause.

Eventually they traced it to a leak (using the green dye) which was letting the gas go over time. The leak was located in a condenser up behind the glove box. No problems since.

Not sure if this will help, but may point you in the right direction.

Cheers

Anthony
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AnswerID: 592564

Follow Up By: Member - Scott M (NSW) - Tuesday, Nov 10, 2015 at 19:10

Tuesday, Nov 10, 2015 at 19:10
My mechanic uses some stuff that glows under UV light. Showed me one time on my Subaru. Couldn't see anything until he pulled out the light wand. Stood out like the proverbial dogs whatis...
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Follow Up By: Member - ACD 1 - Tuesday, Nov 10, 2015 at 19:19

Tuesday, Nov 10, 2015 at 19:19
That sounds like the same stuff.

I was very suprised when he pulled out the condenser how much dust and crap was sucked into the heat exchange fins.

Cheers

Anthony
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Follow Up By: Zippo - Tuesday, Nov 10, 2015 at 22:39

Tuesday, Nov 10, 2015 at 22:39
Yes, it is a TX valve (Thermostatic expansion). And the condenser is out the front, where the hot refrigerant gas condenses to liquid form. The refigerant then vaporises at the TX valve at the inlet to the EVAPORATOR which is the under-dash "coil" and returns to the low pressure side of the compressor.
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Follow Up By: Member - ACD 1 - Tuesday, Nov 10, 2015 at 23:31

Tuesday, Nov 10, 2015 at 23:31
Thanks Zippo


Wouldn't it be great if I could go back and edit the correct term in.

Given it is on the low pressure side this is probably the reason it lasted for a while after regassing.

I know once they found the leak in the evaporator and replaced it - no more issues. It was only persistence on the part of the shop I sent it to that found the leak. Toyota just kept putting gas in.

Cheers

Anthony
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Follow Up By: Zippo - Tuesday, Nov 10, 2015 at 23:52

Tuesday, Nov 10, 2015 at 23:52
Anthony, sorry if that sounded patronising - it was simply meant to clarify things. And yes, an edit button (as found on many forums) would certainly be a welcome addition for most of us - myself included.
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Follow Up By: Member - ACD 1 - Wednesday, Nov 11, 2015 at 00:23

Wednesday, Nov 11, 2015 at 00:23
No! Not at all Zippo.

Just saying it would be good if I could edit the correct term into my response so that it made sense.

Unfortunately it will always be incorrect - so if someone only reads my response they get incorrect info.

Glad someone could clarify it - that's why I put the (?) because I wasn't certain of the term.

Does my theory of losing the gas slowly make sense? If it was on the high pressure side, I would expect to lose it much quicker.

When the aircon guy showed me the evaporator and the glove box with his UV light, you could see quite clearly where it leaked. It was only the tiniest of holes.

Cheers

Anthony
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Reply By: Member - Tony F8 - Tuesday, Nov 10, 2015 at 18:43

Tuesday, Nov 10, 2015 at 18:43
Mate if he didn't do the dye test, take it to someone else, sounds like everything else is fine, I would go with the previous poster regarding a leak.
AnswerID: 592565

Reply By: swampy - Wednesday, Nov 11, 2015 at 10:45

Wednesday, Nov 11, 2015 at 10:45
hi
Either a very dirty evaporater [ bit in dash] [cannot heat exchange due to blocked /insulated with dust hair etc ]
The evaps then freeze up go icey then defrost which gives running issuses
or
Lack of refrigerant due to leak
symptom is when the compressor cuts in it sucks the low pressure side down so low that it cuts out on the safety low pressure switch

Most issues can be seen once aircon gauges have been connected

ALL EVAPS NEED CLEANING EVERY 100,000kms

Dirt left on evap fins rots the very thin alloy fins causing premature failure

Always change tx valve when evap out of car
Always change receiver drier when system open
If your system was originally R12 gas change over to the 134a evap and tx valve
Due to age and most likely many kms [80 series were/ are very reliable ]
CHANGE THE HIGH / LOW PRESSURE hoses [available in a kit ]

cheers swampy
AnswerID: 592583

Follow Up By: Zippo - Wednesday, Nov 11, 2015 at 12:14

Wednesday, Nov 11, 2015 at 12:14
What he said.

If the compressor is NOT cycling then the evap is icing up.
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Follow Up By: Lachlan T - Wednesday, Nov 11, 2015 at 13:03

Wednesday, Nov 11, 2015 at 13:03
Thanks mate

Ill get my mecho to hook his guages back on to it and give it another check sounds like ill have to pull the evaporator out and give it a clean also

Cheers
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Follow Up By: swampy - Wednesday, Nov 11, 2015 at 13:24

Wednesday, Nov 11, 2015 at 13:24
hi
if the high pressures are reading low
low pressures reading low
system is down on refrigerant
static pressure with both hoses connected is around 100 psi for normal system
The condenser [in front of radiator ] may be suffering from a lot of stone chips and once again highly likely its leaking from this .
MANY AIR CON LEAKS DONOT HAPPEN ALL THE TIME
SOME LEAK ONLY UNDER CERTAIN CONDITIONS

Be prepared for tx valve ,evap , condenser and hoses ,receiver drier , many orings
lube all joints with fridge oil
The evap to suction hose connection may be frozen together [this happens from age and the constant temp cycling ]
Remove compressor and have flushed & reoiled at local aircon shop

If the compressor is Nippon these are able to be reconditioned by NDenso aust
These are fairly reliable

swampy
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