I have only had my Fiesta a couple of months from new and have mixed feelings about the performance of the automatic temperature control. When it has been cold outside the heater blows out hot air quickly heating the car. But on warm days the air blowing out of the vents is not cool enough and does not blow out with enough force.My preference is to not have cold air blowing directly at me but cooling the whole atmosphere inside the car, sadly I don't think the Fiesta is up to this. To be fair my previous car (Honda Jazz) was just the same. Car manufacturers are now using smaller AC compressors so there is less strain on the engine and therefore less impact on fuel consumption.

Might get a thermometer with a probe and measure the air blowing out. Does anyone know what the AC air temp at the vents should be?

there should a a temp drop of around 10c , so outide temp 20c, inside vent temp 10c, outside 28c, inside vent 18c. Get the idea.

On this some one said if you use the recirculation it keeps the cold air in.....makes sense. However I wondered does this air still pass through the a/c part or is this only fresh air that goes through it ?

Recirc air is cooled by the a/c.

Previously on this thread I said that I didn't think the air at the vents was cool enough. well yesterday was a warm day and the air temp at the vents felt colder, perhaps it reacts to the outside temp. Anyway it kept the car interior at a comfortable temp.

On this some one said if you use the recirculation it keeps the cold air in.....makes sense. However I wondered does this air still pass through the a/c part or is this only fresh air that goes through it ?

Depends on the car. Some off them just push the air around the system. Some push it back through the AC equating to more cool air at the compromise of eventual humidity :)

Turn it off for 2mins whilst the air is replaced and then back on again

On this some one said if you use the recirculation it keeps the cold air in.....makes sense. However I wondered does this air still pass through the a/c part or is this only fresh air that goes through it ?

The idea of using recirc is that the cabin air goes back through the AC. The AC applies a temperature drop to whatever air is going through it so if you want maximum effect, you feed in the coolest source of air.

Remember that in Britain when the cabin gets hot, it is usually only because the sun is heating the car, not because the outside air is significantly hotter than what you want in the car. Recirc is not necessarily the best setting. If it doesn't feel effective have you increased fan speed?

Surprised only temperature is being considered re aircon. I have always left a/c or climate control on all year round not just for temperature but for humidity. The UK is a high humidity climate hence on hot humid days you might find water p1ssing out under your car. Drove a car around California, Nevada and Arizona which was very dry air not a drip. At home pulled into a petrol station half an hour after picking up new Grand Cherokee and it was p1ssing all over the forecourt. As the forecourt was greazy I thought it was a disaster called the dealer and said they forgot to warn me about the aircon. Dehumidifying the air as well as cooling it makes long journeys much more pleasant IMO

Hi I used to do automotive air con , if you set the temp to minimum and fan speed on 1 or 2 and air direction to dash vents only you should get a temp of 5 degrees roughly. If you are getting 7 or above gas may be slightly low. Some cars vary dependent on pipe routing etc and how far away from the evaporator. R134a gas is not as good as the old R12. Recycle mode to on will also help as some have already said / told you. Also it will work better driving along as the pump is circulating it faster and the condenser cools better too.

i found on my ST3 2015 that the aircon/climate is not a patch on cold as my last car 2.2 mazda .

just does not get cold even on low.

Surprised only temperature is being considered re aircon. I have always left a/c or climate control on all year round not just for temperature but for humidity. The UK is a high humidity climate hence on hot humid days you might find water p1ssing out under your car. Drove a car around California, Nevada and Arizona which was very dry air not a drip. At home pulled into a petrol station half an hour after picking up new Grand Cherokee and it was p1ssing all over the forecourt. As the forecourt was greazy I thought it was a disaster called the dealer and said they forgot to warn me about the aircon. Dehumidifying the air as well as cooling it makes long journeys much more pleasant IMO

In Britain most of the time, the cabin temperature is higher than outside temperature; if not actually using the heater, it is being heated by the sky. This is a different condition to trying to maintain the cabin at a significantly lower temperature than outside. The main idea of using AC to take water out of the air in colder weather is to stop it condensing on cold glass.

But the concept of humidity is widely misunderstood; a relative humidity reading is not a direct measure of water content. For instance, 100% at 5C is the same amount of water (absolute humidity) as 15% at 35C.

There is yet another element to comfort - air movement. I think it is the most important.

In Britain most of the time, the cabin temperature is higher than outside temperature; if not actually using the heater, it is being heated by the sky. This is a different condition to trying to maintain the cabin at a significantly lower temperature than outside. The main idea of using AC to take water out of the air in colder weather is to stop it condensing on cold glass.

But the concept of humidity is widely misunderstood; a relative humidity reading is not a direct measure of water content. For instance, 100% at 5C is the same amount of water (absolute humidity) as 15% at 35C.

There is yet another element to comfort - air movement. I think it is the most important.

This just looks like a straight multiplication to me [is this the case? because I don't know]

Assuming it is then if you take a more realistic set say 23C with 60% humidity then the number 'absolute or not' is 1380 or rather, a lot of water which was actually spewing out of my little Fiesta Ecoboost 1L the other day

This just looks like a straight multiplication to me [is this the case? because I don't know]

Assuming it is then if you take a more realistic set say 23C with 60% humidity then the number 'absolute or not' is 1380 or rather, a lot of water which was actually spewing out of my little Fiesta Ecoboost 1L the other day

There are conversion tables on the net. Certainly, removing water from the air is a by product of cooling it. But the water being collected would otherwise stay in the air going through the car without collecting somewhere else - such as it does on the glass in cold weather.

I am not an expert, just interested in the subject. Casting around, a lot of work has been done on aircraft comfort. One of the USPs of the Boeing 787 with its composite structure is that it allows a higher humidity than aluminium. 16% instead of 10%. But studies suggest that people perceive under 40% as feeling dry. It is reckoned that 40-70% is the ideal range. (All at the low 20's C of course.) So in the conditions you give, AC is used to counter the heating effect of sky radiation, certainly, but it seems the water extraction effect is irrelevant.

For my part last week, there was plenty of radiation heating but outside air was 15-18C. So I did my usual thing of using the fan as primary control and only dibbing the AC when on position 3.