Technical A/C performance data.

[judderbar]

A/C performance data and cleaning

I am wondering if my A/C is in top condition. The car is now 12 years old, It was regassed in 2013 and I cannot say I noticed it being any different. I replaced the clutch bearing in 2014 and there was no signs of any leakage from the seal.

Is there any information out there for these cars to give what kind of cabin temperature we can expect for a set of outside temperatures?

At the moment all I know I can get 4.6C coming out of the front and lower vents with fan on 4 without internal circulation when it is 15.8C outside and the car is warmed up in the driveway and the cabin filter is needing to be replaced.

1. Is it possible to get an endoscope into the interior to see the condition of the evaporator? I suppose I will have to try it and let you all know.

2. While the system is still full of gas is it possible to access the evaporator and give it a clean if it needs it?

3. Does the evaporator clean itself over time by being washed with the water dripping off it? I seem to recall my home dehumidifier back in NZ, which was protected by a filter, was spotlessly clean inside but i am wondering about it anyway. A few years ago I ran the car for at least a year without the pollen filter in place and then when I replaced it the air was getting around it anyway because the seals were cracked - which hopefully is now fixed.

Anybody out there (Flisko perhaps) who has had a look at these things to let me know what they look like inside?

I had a look at the condensor in front of the radiator last year and it seemed totally fine.

 

[jackwhoo]

Replace cabin filter and see how you get on.
If it's cool enough for you to be comfy it's working well. Amazingly good for age of car.
4.6 degrees is a very good out put temperature.
The evaporator looks like a compact version of the one on your home dehumidifier evaporator.
cabin filter stops it getting clogged. If there was any clogging it would reduce volume of air flow. You haven't mentioned any air flow problem so most likely it's fine.

 

[judderbar]

Replace cabin filter and see how you get on.
If it's cool enough for you to be comfy it's working well. Amazingly good for age of car.
4.6 degrees is a very good out put temperature.
The evaporator looks like a compact version of the one on your home dehumidifier evaporator.
cabin filter stops it getting clogged. If there was any clogging it would reduce volume of air flow. You haven't mentioned any air flow problem so most likely it's fine.

the 4.6C is when it is 15.8C outside.

Yes, the airflow does not seems very restricted but then if there is a layer of crud on the evaporator it might not be so restrictive and yet make a difference?

There is no obvious difference between hot air flow and cold air flow. Do you know if the hot air always passes through the evaporator? I am supposing it does to enable winter demisting. I wonder how they switch out hot to enable cooling though??

 

[jackwhoo]

Re: A/C performance data and cleaning

I am not 100% sure for your car but usually the air flows through cabin filter then evaporator then there is the cold/hot air flap. The cold/hot flap controls how much of the air passes through the heater matrix or bypasses heater matrix entirely ie hot-all air through heater , or cold-all air bypass Heater.
If there is some dirt on evaporator it will make litre difference unless it is special insulating dirt.

To me an 11 degree drop in air temp with fan on full is good, remember the air is not around evaporator for much time at that rate of air flow.
In Finland is a 10degree drop in air temp insufficient?
If you want to take it apart and have a look give it a go , please post pictures as I would be interested.

 

[judderbar]

Re: A/C performance data and cleaning

I am not 100% sure for your car but usually the air flows through cabin filter then evaporator then there is the cold/hot air flap. The cold/hot flap controls how much of the air passes through the heater matrix or bypasses heater matrix entirely ie hot-all air through heater , or cold-all air bypass Heater.
If there is some dirt on evaporator it will make litre difference unless it is special insulating dirt.

To me an 11 degree drop in air temp with fan on full is good, remember the air is not around evaporator for much time at that rate of air flow.
In Finland is a 10degree drop in air temp insufficient?
If you want to take it apart and have a look give it a go , please post pictures as I would be interested.

Thanks for your interest. I was able to quite easily take an endoscope picture of the first A/C heat exchanger. Totally clean and shining brightly in places.

I replaced the cabin filter which gives a greater flow and now with a similar 15C outside temperature I get 7C vent temperature.

These measurements are taken with no sun. Even with a low air temperature it can get fairly hot quite quickly at this time of the year, and the impression I am getting is that the A/C is not working like it used to. It could be I am getting hypnotised into thinking something is wrong by the demands of an 8 year old for more "colding" and a wife who wants hot or cold A/C to be continually on outside air.

 

[jackwhoo]

Re: A/C performance data and cleaning

I can know see the source of your problem................................. It is the demands of your family.

You may get colder air with fan on 3 or even 2 because the air will be near the cold evaporator for longer .
When your turn on ac does the fan for condenser run?
Apart from that the only thing I can think of is go to an ac place for check of gas pressure .

 

[jackwhoo]

Re: A/C performance data and cleaning

Thanks for your interest. I was able to quite easily take an endoscope picture of the first A/C heat exchanger. Totally clean and shining brightly in places.

I replaced the cabin filter which gives a greater flow and now with a similar 15C outside temperature I get 7C vent temperature.

These measurements are taken with no sun. Even with a low air temperature it can get fairly hot quite quickly at this time of the year, and the impression I am getting is that the A/C is not working like it used to. It could be I am getting hypnotised into thinking something is wrong by the demands of an 8 year old for more "colding" and a wife who wants hot or cold A/C to be continually on outside air.

Good picture, thank you.
The air in car does go stale quickly if air on recirculate.

 

[AndyRKett]

Re: A/C performance data and cleaning

A healthy air con system should get about 15'C drop on outside air temp, however you might see that if it was 30'C outside but the closer it gets to zero the harder it is for the system to continue to reduce temperatures.

Basically you don't want the evaporator freezing the moisture that it's removing from the air, otherwise as it freezes it blocks the evaporator. So the temperatures you're seeing are spot on and you wouldn't want it any colder.

Because it works by compressing and expanding gas there is little to go wrong with it, as long as it's not leaking and the pump works

 

[judderbar]

Re: A/C performance data and cleaning

A healthy air con system should get about 15'C drop on outside air temp, however you might see that if it was 30'C outside but the closer it gets to zero the harder it is for the system to continue to reduce temperatures.

Basically you don't want the evaporator freezing the moisture that it's removing from the air, otherwise as it freezes it blocks the evaporator. So the temperatures you're seeing are spot on and you wouldn't want it any colder.

Because it works by compressing and expanding gas there is little to go wrong with it, as long as it's not leaking and the pump works

It will be interesting to see what kind of temperatures I get during a warmer day. The system does not seem to be working very hard at the moment. Cycling in and out with the fan coming and going.

One thing i did find was the condensor at the front of the car was a bit damaged. We hit something once while parking and it looks like it pushed the condensor forwards to make it bowl shaped so it was nearer the hot water radiator. The condensor was also looking fairly cruddy. Straightened it and cleaned it up but it makes no difference that i can see so far.

 

[AndyRKett]

Re: A/C performance data and cleaning

One thing i did find was the condensor at the front of the car was a bit damaged. We hit something once while parking and it looks like it pushed the condensor forwards to make it bowl shaped so it was nearer the hot water radiator. The condensor was also looking fairly cruddy. Straightened it and cleaned it up but it makes no difference that i can see so far.

I fitted air conditioning to a Mondeo about 12 years ago using a condenser from a car that had been in a very heavy front end accident, it was quite bent out of shape but still held gas and straightened up ok, worked well for a good few years before the care was written off hitting a dear.

Being near the radiator makes no difference, the compressor heats the gas as it compresses it, then it travels through the condenser to try and get rid of the heat, at this point the gas it probably as hot as the coolant.

Fiat condensers loose the fins as they get older, the aluminium corrodes and the fins fall out in long 'zig-zag' strips you can still loose most of the fins without any noticeable difference to performance.

 

[judderbar]

Re: A/C performance data and cleaning

I fitted air conditioning to a Mondeo about 12 years ago using a condenser from a car that had been in a very heavy front end accident, it was quite bent out of shape but still held gas and straightened up ok, worked well for a good few years before the care was written off hitting a dear.

Being near the radiator makes no difference, the compressor heats the gas as it compresses it, then it travels through the condenser to try and get rid of the heat, at this point the gas it probably as hot as the coolant.

Fiat condensers loose the fins as they get older, the aluminium corrodes and the fins fall out in long 'zig-zag' strips you can still loose most of the fins without any noticeable difference to performance.

Oh well. Next job is to look at the heater motor. Checking voltages and cleaning it inside if necessary.

 

[jackwhoo]

Re: A/C performance data and cleaning

It will be interesting to see what kind of temperatures I get during a warmer day. The system does not seem to be working very hard at the moment. Cycling in and out with the fan coming and going.

One thing i did find was the condensor at the front of the car was a bit damaged. We hit something once while parking and it looks like it pushed the condensor forwards to make it bowl shaped so it was nearer the hot water radiator. The condensor was also looking fairly cruddy. Straightened it and cleaned it up but it makes no difference that i can see so far.

I am not sure the fan should be cycling on and off , if ac on I thought condenser fan should be on.
Fingers crossed we will get an explanation of condenser fan control system.

 

[jackwhoo]

Re: A/C performance data and cleaning

I am not sure the fan should be cycling on and off , if ac on I thought condenser fan should be on.
Fingers crossed we will get an explanation of condenser fan control system.

If when you say cycling in and out ,the ac compressor cutting in and out I would say your gas pressure could well be low causing this problem.

 

[AndyRKett]

Re: A/C performance data and cleaning

Compressor will cycle on and off in normal use, that is not a problem at all, normal radiator fan will cycle on and off with the compressor to cool the evaporator when the air con is running again this is perfectly normal.

If gas pressure is low it is actually less likely to cycle on and off as the system isn't able to build enough pressure to trip the pressure high sensor.

 

[judderbar]

Re: A/C performance data and cleaning

If when you say cycling in and out ,the ac compressor cutting in and out I would say your gas pressure could well be low causing this problem.

I oiled the motor which was surprising stiff even with the brushes lifted. Oiling it made a bit of a difference when turning it by hand so now it is feeling much more like it used to. That wall of pure air sound.

Withe the engine running, there is quite a large 2.5V voltage drop at the motor with respect to the alternator voltage. It might be worthwhile to upgrade the wiring to get a bit more fan power and run a dedicated wire from the alternator to an isolated fan relay if that fits in with the existing switches.

With the engine off, Fan 1 voltage is 3 then 5 then 7 then 9.9 on 4 with a battery voltage of 12.1. With the fan switch on and the fan plug disconnected there was 11.1 at the disconnected unloaded plug. Voltage drops were similar for the two wires so I am assuming cleaning up the connections is not going to make much difference.

 

[judderbar]

I had another fiddle around with the wiring, took out some relays and fuses and cleaned up a connection. Its good enough.