Air Conditioning, tricky fault if any can suggest a cause.

56split

Active Member
Apr 28, 2015
1
0
Southport
Hello and thank you in advance for taking the time to read this.

I will try and get as much detail down to give the diagnostic heroes amongst you all the info I can.

I am working on my friends 2011 Exeo Sport Tech st. The AC hasn't been working for a while as the dreaded G65 error code/Econ light issue.

I have VCDS and the scan is now clear (apart from glow plug 3!!) and the Econ light goes out but still no air.
The comp is a denso variable model, not the clutch type.
There is voltage at the N280 control solenoid and in VCDS the measure blocks show it operating fine (amps rising and falling when econ button cycled) as is the G65 and compressor state.

With the ac gauges connected the static pressure today was about 50-60 psi which at 14 degrees C seems about right.

The issue is when the air con/Climate button is pressed there is absolutely no movement between the pressures of the high and low side.
As all the VCDS and voltage checks seemed ok I am veering to the variable swash plate in the compressor or the pulley being sheered

Today the compressor came off (after pumping down) and the n280 was tested and the solenoid operates. The pulley was removed and is fine the shaft turns smoothly with no hint of any black death or metal in the oil.

While the comp was off the lines were blown through to check for blockages, none found all pipes seemed clear. The evaporator expansion valve was removed and cleaned/checked, all ok.

With shaft, pulley and solenoid ok the comp was put back on, system vacuumed out pressure tested and re-gassed.

Exactly the same, no movement whatsoever between the high and low gauges when ac turned on.

Has anyone come across this before as i'm scratching my head now?
Does anyone have any wiring diagrams by any chance?

Any help/suggestions as to how I should proceed would be greatly appreciated.

Many thanks,

Mike.
 

smutts

Active Member
Apr 12, 2020
372
188
There needs to be a restriction for the pump to compress against,
heat is lost, the gas condenses, blasts through the restriction to the low pressure suction side, boils and cools you.
Repeat.
If the pump is working, but the thermostatic expansion valve (a variable restriction controlled by a thermostat) is stuck wide open, then there will be no difference in pressure & so no cooling.
Not my speciality, so if someone knows better, please pipe up.
 
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