Discussion
The recently bought C30 D5 aircon hasn't worked since I got it - the local stealer suggested almost £500 to change the condenser (which I politely declined) and so I took it to my friendly local (a VAG specialist!) who have carried out a leak test and confirmed it's not leaking.
They've said it's holding pressure but apparently the air con pump engages then lets go almost instantly so nothing gets pumped round. A quick search of the net reveals it may be a pressure switch failing but I can't seem to find a picture of where to look for it/them.
Does this seem right and if so, where it it / are they and are they an easy check / fix?
Thanks in advance
They've said it's holding pressure but apparently the air con pump engages then lets go almost instantly so nothing gets pumped round. A quick search of the net reveals it may be a pressure switch failing but I can't seem to find a picture of where to look for it/them.
Does this seem right and if so, where it it / are they and are they an easy check / fix?
Thanks in advance
imagineifyeswill said:
The pressure sensor will be in one of the pipes usually near the front and fairly obvious, as already said not DIYable as need degassed before removing sensor.
Shouldn't be a problem as my friendly garage removed all the gas after doing the pressure checkGreenV8S said:
If you suspect the problem is in the switch you should be able to confirm that by disconnecting the switch and making/breaking the circuit manually.
Is it as simple as sticking a wire in the contacts to complete the circuit and then seeing what happens? Will the pump then engage all the time? Presumably as there will be no gas (or oil) I'd better not let it run too long if it does...It is not always as simple as bridging the wires, on modern cars they no longer use those type of pressure switches where it is a simple turn on or off at predefined Pressures.
Cooling Fans and Compressors are now run electronically, as part of a network or PWM controlled so they can be run at any speed, and the speed they actually run at is fed back to the ECU for Fault Detection purposes. Hence when you turn the AirCon ON, or Your Cooling Fans Cut in the Engine Doesnt nearly stall. Remember that from the old bangers ?
FYI, moments befor the fans, Compressors and other High Consumption Consumers are Commanded the ECU has the option of raising the idle speed a tiny little bit to keep you, the driver in the dark about what is going on, a more pleasurable & less worrying experience !
Instead they fit a Pressure Sensor as opposed to a swith that will accurately read the pressure and report to an ECU. Then that or another ECU in the network will calculate weather the Compressor, Fans etc should run & at exactly what speed.
So bridging the wires will just look like a short circuit to the ECU, paralyse the system and Throw A Fault Code.
The next logical step here is to get it diagnosed with a good scan tool and confirm what is wrong first, makes no sense to throw a "Pressure Switch" at it if you don't know if it is faulty.
A faulty Ambient Temperature Sensor & A Faulty Engine Water Pump are just 2 examples that I personally have found to be faulty on cars stopping AIR CON.
As for the Schrader Valve behind the Sensor or Switch - Please Check !! A 2007 VW has it so sensor replacement is DIY, however I replaced one this Week on a Mercedes E Class 2014 and it did not. So no rhyme nor reason sometimes.
Good luck
Cooling Fans and Compressors are now run electronically, as part of a network or PWM controlled so they can be run at any speed, and the speed they actually run at is fed back to the ECU for Fault Detection purposes. Hence when you turn the AirCon ON, or Your Cooling Fans Cut in the Engine Doesnt nearly stall. Remember that from the old bangers ?
FYI, moments befor the fans, Compressors and other High Consumption Consumers are Commanded the ECU has the option of raising the idle speed a tiny little bit to keep you, the driver in the dark about what is going on, a more pleasurable & less worrying experience !
Instead they fit a Pressure Sensor as opposed to a swith that will accurately read the pressure and report to an ECU. Then that or another ECU in the network will calculate weather the Compressor, Fans etc should run & at exactly what speed.
So bridging the wires will just look like a short circuit to the ECU, paralyse the system and Throw A Fault Code.
The next logical step here is to get it diagnosed with a good scan tool and confirm what is wrong first, makes no sense to throw a "Pressure Switch" at it if you don't know if it is faulty.
A faulty Ambient Temperature Sensor & A Faulty Engine Water Pump are just 2 examples that I personally have found to be faulty on cars stopping AIR CON.
As for the Schrader Valve behind the Sensor or Switch - Please Check !! A 2007 VW has it so sensor replacement is DIY, however I replaced one this Week on a Mercedes E Class 2014 and it did not. So no rhyme nor reason sometimes.
Good luck
These cars are very well known for condenser failure. When my C70 had non functioning air con they pressure tested it and were adamant it was holding gas, so topped it up. Two days later it escaped.
Have they extracted the gas to confirm it had stuff in it, and put in the right amount?
Have they extracted the gas to confirm it had stuff in it, and put in the right amount?
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