air conditioning not cold RESOLVED, over pressure

Marlin · Post by **Marlin** » 29 Mar 2011, 14:16

Hi,
I have a V70 T5 2002 with 80000mls on the clock and the air con is not getting cold,
I have had the system vacuum leak tested and recharged and there are no leaks in the system.
The compressor cycles on and off about every 10 seconds , when it is on there is a good12v supply to the compressor.I have read on forums about bridging the compressor clutch control relay so tried this .-I wont be doing that again!!

As soon as I bridged the relay with a fusable link the compressor kicked on and stayed on and the air in the car started going ice cold BUT after about 40 seconds of operation Gas was discharged out of the front of the car!!!! untill I switched the ignition off(I assume there is some kind of over pressure valve in the condenser?)
I am beginning to think that there is maybe a blockage in the high presssure side of the system and maybe the drier or the expansion valve is at fault?
Has anyone come accross this before?
Any ideas would be appreciated.
Many Thanks.

Post by **JRL** » 29 Mar 2011, 15:43

There's an evaporator module in these cars that can go bad
jimmy5 will probably say more about this when he reads it

Post by **jimmy57** » 29 Mar 2011, 16:38

The fact it dumped gas via the overpressure relief is the first thing to address. The fan should have come on and prevented high side from reaching the 400+ psi pressure where relief opens.
Does the cooling fan work?
The pressures can be checked. The high side is next to RH hood latch and the low side port is directly in front of timing belt cover on the frame rail. The cooling duct for module box may be in the way. Not certain of the layout of the cooling duct on RH drive cars. With engine at high idle (1500 rpm) the low side should be 22-30(1.5-2.0) Bar and high side 150-180 (10-12 Bar) at temps no higher than 85F/30C. The relief opens at just over 400 PSI but compresor shutoff via the pressure sensor should have cut A/C off before that. Your compressor not running any longer than it does could be high pressure related.
When it is cooling normally and car has cooled down the compressor will cycle frequently due to evaporator temp probe sensing and CCM regulation of compressor.

Marlin · Post by **Marlin** » 30 Mar 2011, 12:32

The cooling fan works ok and was on when it dumped the gas when I bypassed the compressor relay.
As for the gas pressures I will get them checked as you advised and update with the results.
If it is as a result of over pressure does this indicate a blockage in the high pressure side of the system?

Post by **jimmy57** » 30 Mar 2011, 13:30

Blockage or faulty expansion valve. Expansion valve throttling down when it shouldn't is effectively an obstruction.

Marlin · Post by **Marlin** » 10 Apr 2011, 13:32

I have now checked the pressures.
I carried out a 45 minute vacuum then regassed to ensure no moisture in the system.
The system has no leaks
The pressures are-- low side 1.8 to 2.8 bar
-- High side 7 to 12 bar
the outside air temperature at the time was 20 degrees celcius
I have checked the clutch compressor gap and it is 0.7mm
Since regassing the compressor does seem to stay running for longer [up to 30 seconds]
The air inside the car does seem to cool but does not chill as much as I think it should,I have tried it on both manual and auto mode and the efficiency seems about the same on either setting. but the warmest day we have had so far is 20 degrees C so I may wait and see how it does when the weather warms up? Or could the clutch gap be causing the lack of efficiency?

Post by **jimmy57** » 10 Apr 2011, 14:01

All readings look very good.
Clutch gap has no bearing on cooling unless it is preventing clutch from engaging.
If the temp from vents is not adequately cool when weather is warmer then the evaporator temp probe will need to be evaluated.
The temp reading via VIDA or other capable scan tool will let you know if the sensor probe is working correctly. If the compressor is turned off and the settings are placed in full cold position the probe's reading will be above the actual ambient temperature. If it is cooler then it will cause the CCM to switch off compressor too much and at too high a temp causing poor cooling from A/C.
The probe can get blockaged from dirt and debris but this usually causes the evaporator to freeze and stop airflow with no compressor cycling. Your observations do not fit the blocked probe scenario.

Marlin · Post by **Marlin** » 12 Apr 2011, 13:39

Thanks for your help.
I will borrow a scan tool and update you with outcome

Marlin · Post by **Marlin** » 05 Jun 2011, 12:40

We have now had some days where the temperature is 25-30 degrees celcius and the air con is now ice cold ,so I can only assume that there was moisture in the system which was freezing and by vacuuming the system for 45 minutes before regassing has removed this.(Unfortunatly I was not able to get a scan tool to check the temperature settings but as all seems fine now I wont need to)
Thanks for your help

go 2 x 2 guy · Post by **go 2 x 2 guy** » 03 Jul 2011, 22:36

I am working on a S60 that at idle the AC blows ice cold with an outside Dallas temp at 90 to 100 with RH in the 50s. I have let it sit at idle for 30 minutes. However, once the RPM goes above 1500 to 2000 the compressor cuts off. The only way to get the system to come back on is to shut off the car for 10 minutes or more. Then I can start the cycle all over.

The high pressure at idle is 250, and I don't know what it is/was when the compressor cuts off.

My guess is that it is a defective high pressure switch, but so far I have been unable to lacate that component to check it out. Is there another component you would suggest is causing this problem.

I need and appreciate any help.