Technical aircon doesnt appear to work 100hp

[dac69er]

Girlfriend recently got a 100hp panda. everything appears to work other than the aircon.

If you press the aircon button, I can't hear anything kick in and the temperature doesn't drop. I assume this could just be low gas, but thought I would check it is not some other issue first?

Thanks all

 

[AndyRKett]

In winter weather it's hard to really 100% say there is a fault.

Fiat put a temp sensor in and if the car is too cold it won't work. Get the cabin up to temp set the heater to recycle the air and turn on the aircon if the temp doesn't start to drop and All the windows mist up then the Aircon isn't working.

Gas is the most obvious fix if that's the case

 

[dac69er]

you sure about this? when you put the demist option on, the fan ramps up, and the aircon should come on to try and dry the air and demist the car quicker. as the aircon doesnt appear to be coming on, it wont be doing much drying of the air.

the light comes on when you press the aircon, just doesnt have any affect on anything (clutch not coming in on compressor)

 

[varesecrazy]

you sure about this? when you put the demist option on, the fan ramps up, and the aircon should come on to try and dry the air and demist the car quicker. as the aircon doesnt appear to be coming on, it wont be doing much drying of the air.

the light comes on when you press the aircon, just doesnt have any affect on anything (clutch not coming in on compressor)

pretty sure THAT'S WHY he suggested it..

to see IF it works for everything EXCEPT drying

Charlie

 

[dac69er]

the windows will only mist up if the temperature is cold. if the aircon doesnt kick in when the temperature is cold then it is never going to demist the car. seems completely stupid to me???

i appreciate there is a point where the outside temperature and the temperature of the aircon condensing rad will be equal so no condensing/drying of the air will occur, but it seems stupid the system wont even come on to attempt it.

if i dont hear the aircon compressor coming on, then its not working. i have tied it with the cabin warmed up, on recirc, when cold in the mornings etc. it just doesnt come on at all.

i just didnt know if this was a normal no gas issue or something more sinister that needs looking into?

 

[Andrewedwardjudd]

Windows misting up in a car is more of a technical challenge when it is several degrees or more above freezing because when it is colder the outside absolute humidity is very low so that any air coming into the car causes a very low relative humidity inside the car ie warm wetter air goes outside and cold dryer air comes inside.

The experts tell me that the AC does not operate below 3C or 5C. Which seems true for my car, but if i warm my car up fully and put it in the garage with the garage door open even when it is many minus degrees the AC compressor will operate.

I live in Finland. Windows steaming up in our kitchen, with no windows open and no fan, when it is -20C does not happen even though we only have twin unsealed glazing (double windows) from the 1960s. Our biggest problem with water in our cold climate is absence of water causing skin drying and itchy rashes at ankles and wrists. There is almost no water in the air when it is colder.

On the other hand if it is 10C outside and it is raining and you get in the car wet or dry, then windows inside a car are going to steam up rapidly as the car warms up inside without airflow from outside - i am still not convinced AC is needed to get rid of the moisture though. 10C outside air is not holding a great deal of water. The situation is very different when it is humid outside on a warm day. I tend to avoid using the AC to dry the car - and my wife does not like recirculated air anyway.

Thinking about it, in our climate we need an indicator that the AC is on, rather than the light, so we can be sure the seals get the use they need to keep them free of corrosion.

 

[portland_bill]

The aircon will not cool the air if it is already at the desired low temp, so the pump does not operate. It is not trying to be a freezer for keeping your food in.

 

[dac69er]

it was 10 degrees outside yesterday and the compressor didnt come in when i pressed the button.

i know it is no a freezer, but im not asking it to work in the antarctic.

if you have an outside temp of 10 degrees and a cabin temp of 20ish then you would expect the aircon to come on if you ask for the temperature to be cooled.

 

[portland_bill]

You will need to get it to the garage and have it regassed. They should evacuate the system, then wait to ensure the vacuum holds, to ensure no leaks. If ok, they will then regas and all should be well.

The system should be regassed every three years ideally, some manufacturers say two years. The gas contains a small amount of oil, to lubricate the pump and keep the seals moist. If the system is not used regularly the seals can dry up. New seals for every pipe joint is tedious, but if the pump seals are gone it is a new or reconditioned pump.

If you've only recently bought it, was there any warranty?

 

[AndyRKett]

I mearly made a suggestion to try and fathom out if there was a fault or simple the weather was too cold.

If you're happy it's nothing to do with being too cold because you tried it on a much warmer day o driven it into a volcano etc then the only logical next step is to get it looked at by someone with a regas machine

 

[Andrewedwardjudd]

You will need to get it to the garage and have it regassed

Out of interest, without putting a pressure gauge on the compressor, can the pressure switch shown in the wiring diagram be used as a guide to the amount of refridgerant left in the system?

I have no idea how this system is working. If the clutch fails to operate how would we begin troubleshooting to find for example a broken wire? Where is the pressure switch for example?

 

[dac69er]

na, no warranty. i always buy and ask for a trade sale for money off. i know what im looking at so i take the chance. once i buy a car i dont want anyone else touching it tbh.

my girlfriend doesnt care about the aircon not working, but i said i will ask if its a simple silly fix before worrying about a regas.

 

[portland_bill]

Diagnosis has to start with the regas machine. This measures current gas content, then evacuates the system, does a vacuum leak test, which tests the seal integrity, then repressurises. Only then can the operation be checked. Pressure switches can only be checked/faulted is there is known pressure for it to sense.

A regas should be about £50 +/-

 

[Gavv8]

i mearly made a suggestion to try and fathom out if there was a fault or simple the weather was too cold.

If you're happy it's nothing to do with being too cold because you tried it on a much warmer day o driven it into a volcano etc then the only logical next step is to get it looked at by someone with a regas machine

Brilliant.

 

[Jerseywurzel]

I`m confused.


I don't hear anything kick in when I switch on the aircon. The light goes on, the window demists. No sound other than the fan?


I`m not technical, but as I understand it (and it seems to work here), the aircon doesn't blow out cold air - it removes moisture from the air.


So if you have temperature dial on hot, the fan blows out warm air and the aircon removes moisture, resulting in warm air that demists.


In the summer, if you have the temperature dial on cold, the fan blows cold air and the aircon removes moisture, resulting in cold air that demists.


Am I completely wrong????

 

[portland_bill]

Am I completely wrong????

Not completely.
A bit of science.

The aircon is a simple fridge. It just cools the air.
Air will absorb moisture. The warmer it is, the more moisture it can hold, which is why summers are often very humid. Conversely, when the air cools, it cannot hold as much moisture, so some condenses out. Just like when you take the milk out of the fridge, if you leave it out for a few minutes, it gathers moisture on its surface as the touching air cools and cannot hold the moisture. The same thing is happening when our windows mist up. The window being cold, cools the touching air, so moisture collects on the glass. We blow warmer air onto it to absorb the moisture, often resulting in a car warmer than we would like in order to be able to see out.

The aircon cools the incoming air. Moisture condenses out, and as the droplets join together it drains out under the car, which is why aircon cars leave puddles. Therefore the incoming air is dryer, so will absorb moisture inside the car more readily, so misting up is cleared more quickly, or is prevented. With the aircon running, the occupants will lose more moisture than otherwise, so drinking plenty of water is necessary to avoid dehydration. Wearers of "soft" contact lenses may find them drying out, so should wear glasses instead.

The air will be cooled down to a minimum temperature. If the incoming air is already at or below the set minimum, the aircon will not operate.

Although teh incoming air is cooled, you can choose to reheat it, so setting the desired temperature inside the car. A great advantage in wet weather is no condensation without overheating the interior.

Hopefully explained, ask again if more required.