possible aircon fault

[matttt]

Hi all

My aircon currently appears faulty and I'm seeking some advice as to whether it just needs regassing or something might wrong like the compressor or fan or something. Any pointers would be much appreciated!

The symptons are:
Noisy motor/fan noise when aircon is switched on. The noise stops when econ is pressed to switch off the aircon.
The air is cold (thankfully) but it doesn't appear to blow strongly even if I increase to maximum. It's the same even when switched to econ mode.

Any experience of similar guys?

What are the symptons when an aircon regas is required?

Thanks
Matt

 

[Gordon Attar]

I learnt last week that the compressors can become a bit noisy(scratchy/bearing noise) when the gas is a bit low and they are not getting enough lubrication from the lubricant in the gas! By the way F1 autocentres do a pressure test before charging with gas(which is a quick way of finding any leaks foc) the regas is £42 inc vat.

 

[Glyn]

You will get fan noise when you put the aircon on as switching on activates the two fans behind the condensors inside the front bumper, however the fans are two speed, a balast resistor is in line which alows switching between low speed and high speed, the resistors do fail occasionally and this leaves only the high speed - which of course is easy to hear. check to see if they start on low speed.

When you say noisy fan - do you mean the internal heater blower?

Do you have manual aircon or climate - it makes a difference on the diagnosis

 

[Motorhead]

Matt,

If the noise is coming from the front rather than the rear of the car it's more likely, as Glyn says, to come from the condenser fans or from the impellor in the HVAC unit itself. If you stick your head down in the footwell area you should be able to hear it more clearly if it's the latter. I believe that the impellor is at the bottom of the HVAC unit so might be accessible without having to remove the fascia and the unit itself.

Jeff

 

[matttt]

ORIGINAL: Glyn

You will get fan noise when you put the aircon on as switching on activates the two fans behind the condensors inside the front bumper, however the fans are two speed, a balast resistor is in line which alows switching between low speed and high speed, the resistors do fail occasionally and this leaves only the high speed - which of course is easy to hear. check to see if they start on low speed.

When you say noisy fan - do you mean the internal heater blower?

Do you have manual aircon or climate - it makes a difference on the diagnosis

The noisy sound I hear isn't the sound of strong blowing - it's more like a grinding/rough sounding motor noise. Difficult to describe! But the noise does stop when in econ mode so I'm almost certain it's related the aircon.

The blower/fan appears to be making the right noises, but the volume of air does not appear to be a strong as the noise suggests! i.e. when cranked up to maximum, the fan/blower sounds like it's blowing hard, but I can't actually feel a strong volume of air from the vents - it's almost as if they're restricted somehow (but all vents are fully open)

How do I determine whether I have manual aircon or climate? I normally set the temperature and set the fan to a lowish setting so that it's not blowing too hard.

 

[matttt]

ORIGINAL: Motorhead


Matt,

If the noise is coming from the front rather than the rear of the car it's more likely, as Glyn says, to come from the condenser fans or from the impellor in the HVAC unit itself. If you stick your head down in the footwell area you should be able to hear it more clearly if it's the latter. I believe that the impellor is at the bottom of the HVAC unit so might be accessible without having to remove the fascia and the unit itself.

Jeff

The noise is definitely coming from the front of car - it's sounds like from within the central dash area. I'll have to check more closely tomorrow.

Does anyone know if the aircon is covered by Porsche extended warranty?

 

[Motorhead]

Matt,

The fan is upstream of the cooling condenser and there are a number of electrically-operated flap valves downstream which then mix the cooled or ambient air with warm air from the heat exchanger and distribute this to the various outlets. Since you're not getting any airflow, it sounds as though something may have happened to the fan - perhaps the impellor is slipping on the motor shaft. Even if one of the flap valves has failed, I'd still have expected a decent flow of air from some of the outlets. There's a fresh/recirculated air flap valve upstream of the fan which admits air to the system, but even if that has failed and is preventing fresh air entering you'd still be getting recirculated air. Have you tried pressing the Circulating-air button to see what happens?

With climate control you just set the required temperature, press the AUTO button and the system regulates the cabin temperature automatically by varying the conditioned air temperature and flow rate. From what you say, it sounds to me as though your car has the standard aircon set-up.

If you have the Porsche extended warranty I'm sure that you'll be covered, but I'd give your PC a call to confirm.

Jeff

 

[matttt]

Thanks for all the replies guys.

I've had a play around with the aircon today. I've found that if I lower the temperature to "Lo", I get full air flow through the vents and the air is super cold! But if I raise the temperature just 1 degree, the airflow becomes restricted somehow. Very odd. I think I'll have to book it in to be checked out.

 

[Glyn]

Sounds like the temperature sensor in the cabin is faulty.
When in "low" mode maximum cooling takes place irrespective of the internal temperature. (same with "high" setting - keeps heating whatever the internal temp) When set at a nominated temperature the system relies on the internal sensor to regulate the temperature - if the sensor is faulty the system thinks its achieved the set temp and just idles.

 

[matttt]

My aircon has been restored!

The noisy motor was indicated as being caused by low gas pressure - something about valves causing a tapping noise (I can't remember exact description).
The hissing/gurgling was a sign of low gas pressure.

Regas at OPC is about £180... gulp!
"It sounds expensive but we do more than just top up the gas. We service the system by stripping it down, cleaning it, check for leaks and then refill."

Very fortunately for me, OPC East London found some corrosion on one of my condensers and it was weeping fluid. They put it through the warranty and it was agreed to change both radiators plus a part called the "desticator" (?? or something like that!). The new rads are painted black and should be more resistant to corrosion unless due to impact damage.

The "desticator" was not in stock so it's on back order and I'll need to bring my car in to have it replaced.

But they have been able to put everything back together and regas, so the aircon now feels super cooled!