Testing The Air Con

[Halloween Man]

Any ideas on - how to test, how effective the Air Con is on a 2002 TdI Gal ?

 

The weather is cold at the moment so , it is hard to determine the difference

between the cold air from the blower and the a/c being on.

 

When I turn on the a/c , I dont notice any difference in engine revs ,

is this normal ?

 

Does the air con work below 5 degrees ?

Are there any tests I can run to make sure it is working OK ?

or do I have to wait for a hot day ?

 

Thanks....

[seatkid]

On the climatronic version, it don't work less than 5 deg C outside ambient. The temperature switch is (but not always) mounted in front of the pollen filter.

There has been a debate about the standard manual ac if this can work below 5 deg outside temp as this version has a temperature switch on the evaporator itself. So if you switch to recirc. and allow the inside air to heat the evaporator, maybe it can be persuaded to work in winter......

[johnb80]

Surely it does work at the than 5 deg in order to reduce humidity in the cabin. On my Gal it certainly does this and is very noticeable when demisting the windscreen.

 

Regards - John

[seatkid]

As far as I know On climatronic it works at 5 deg and above (indicated outside ambient). At 4 deg and below it stops.

[johnb80]

As far as I know On climatronic it works at 5 deg and above (indicated outside ambient). At 4 deg and below it stops.

But it then would be unable to dehumidify ?

[seatkid]

correct, but at that temperature you would generally be using lots of heat, which helps to dry things out.

[johnb80]

Strangely it doesn't! What the climate control SHOULD do (not certain on the Gal but it does this on other fords) is recycle some of the air and it goes over the chilled evaporator which condenses the water out of the air, the air is then heated and goes back in the cabin. I checked on my Gal tonight, 1 deg C showing on the panel and the compressor was cycling as normal, the heater was also heating the air at the same time, soooooo, I think my theory is right.

I have noticed before if you have ECON mode on, the windscreen takes for ever to demist on a cold morning.

 

Regards - John

[Guest airconman]

Strangely it doesn't! What the climate control SHOULD do (not certain on the Gal but it does this on other fords) is recycle some of the air and it goes over the chilled evaporator which condenses the water out of the air, the air is then heated and goes back in the cabin. I checked on my Gal tonight, 1 deg C showing on the panel and the compressor was cycling as normal, the heater was also heating the air at the same time, soooooo, I think my theory is right.

I have noticed before if you have ECON mode on, the windscreen takes for ever to demist on a cold morning.

 

Regards - John

John,

You are spot on how you,ve described the operation of the aircon system. It is exactly what it says it is - an air CONDITIONING system so it is able to deliver warm, de-humidified air. There is a safety device fitted and this prevents the air leaving the evaporator coils falling bellow 0 degrees C. It does this by sensing the temperature and once it reaches its lower limit the 12v supply to the compressor clutch coil is cut off, so the compressor clutch dis-engages and the refrigeration process is stopped until the temperature reaches its cut-in level and the compressor cuts back in. Remember just because the belt driven pulley on the front of the compressor is turning, it does not mean the compressor is turning as well. Only when the very front clutch plate on the compressor is turning is the compressor running.

Now to answer the origanal question. To determine accurately if your system is running correctly you will require the services of a quallified air con engineer (of which i am one ) who will have the correct equipment to read the system pressures and temperatures. For a quick self dignosis, check the sight glass for bubbles - indicating a low refrigerant level, check the wider of the two air con hoses is a lot colder than the narrower one - which should be quite hot to the touch so be carefull!! Last but not least, if the clutch is not cutting in the system could be low on refrigerant and the low pressure switch has operated and cut off 12v to the coil.

Hope this is of some help. If you need to know anything else give me a call on 0781 260 7592. I run my own Mobile Vehicle Air Conditioning businss on the south coast.

DRIVE COOL - ARRIVE COOL Airconman

[seatkid]

:D I beg to differ....

 

There are fundamental differences between models fitted with a VW engine and those with Ford engines.

 

Models fitted with VW engines do not have a deicing switch fitted in or near the evaporator. Those with Ford engines do. This seems to be because VW power units are fitted with variable displacement pumps which dont cycle like the Ford fixed displacement units.

 

There is no sight glass on my Alhambra (or any other modern VAG model that I've seen) Its years since I've seen a car fitted with a sightglass.

 

Both the Climatronic and manual versions have no capability to "partially" recirculate the air. Its either external or recirc.

 

The "valve" people are refering to is usually the 2nd filling point hidden behind the drivers side indicator.

[johnb80]

Well I'll leave this to the experts Seatkid and airconman, I will however state I'm pretty sure my Gal (Nove 2003) has a VW engine with it being 1.9 TDi 115, my compressor definately cycles at less than 2 deg ambient temp.

 

Regards - John