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Old 24th January 2010, 15:41   #1
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Default Tip to keep your AC condensor from going

Mods: could not find this anywhere please move/delete if this is a repetition.

Firstly the condensor is the part of the AC that gets cold and has air blowing through it. It is usually located inside the dashboard.

The condensor is usually made of aluminium and is made of a very thin gauge to aid in heat exchange.

During normal AC operation the condensor gets very cold and the air blows through it. The problem starts when you switch off the AC or more specifically the blower. The instant the blower is switched off, air stops flowing through the condensor. Howerver the condensor is still quite cold. Due to this water starts to condense on the condensor. Much like on a cold bottle. This water causes the condensor to corrode over time.

Most people thinlk aluminium does not corrode. This is not entirely true. Aluminium forms a layer of aluminium oxide over it which helps to prevent corrosion. The problem with the condensor is that the air blowing through the condensor keeps removing the aluminium oxide layer.

The only remidy to this problem is to keep the blower on without the compressor for a while before switching off the AC. This lets the condensor reach room temperature before the air flow is stopped.

Please note that this takes years and is more pronounced in humid environments.
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Old 24th January 2010, 16:55   #2
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Interesting tip Leop,

Turning the compressor off but leaving the blower on for a more gradual temperature change also has one more advantage -- it will probably prevent your spectacles from fogging up


I'm not doubting that the practise might have value, but....

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....Aluminium forms a layer of aluminium oxide over it which helps to prevent corrosion. The problem with the condensor is that the air blowing through the condensor keeps removing the aluminium oxide layer....
...i'm not sure this is accurate.

I'm no chemistry expert, but from what i know it is air itself that CREATES the aluminum oxide layer! (More specifically, the oxygen in the air).

The layer is created almost instantly when aluminum comes in contact with oxygen. Infact, its this layer that makes glueing aluminum so difficult!


Perhaps the moisture and the repeated and sudden temperature changes have more of a part to play on long term condensor damage?

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Old 24th January 2010, 17:18   #3
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Default Terminology is amiss.

Dear Leop,
please replace the word Condenser here in your article with "Evaporator". The condenser is the radiator like thing that sits in front of the engine radiator. Its jobs is to condense refrigerant gas into liquid from the gaseous state. The Evaporator is the part that goes cold up to about 1 to 2 degrees Celsius which is situated in the passenger compartment. The function of the evaporator is to take heat from the passenger compartment to evaporate the liquid refrigerant that has been liquefied earlier by the condenser with help from the AC compressor.

Next point that is amiss is that it is impossible to blow of the aluminum oxide layer with the strongest of air blowing over it neither can one wash of the aluminum oxide layer with the strongest of water jets. Chemical treatment is the only option for removing the oxide layer and that too in an inert environment.

Quote:
Originally Posted by Leop View Post
Mods: could not find this anywhere please move/delete if this is a repetition.

Firstly the condensor is the part of the AC that gets cold and has air blowing through it. It is usually located inside the dashboard.

The condensor is usually made of aluminium and is made of a very thin gauge to aid in heat exchange.

During normal AC operation the condensor gets very cold and the air blows through it. The problem starts when you switch off the AC or more specifically the blower. The instant the blower is switched off, air stops flowing through the condensor. Howerver the condensor is still quite cold. Due to this water starts to condense on the condensor. Much like on a cold bottle. This water causes the condensor to corrode over time.

Most people thinlk aluminium does not corrode. This is not entirely true. Aluminium forms a layer of aluminium oxide over it which helps to prevent corrosion. The problem with the condensor is that the air blowing through the condensor keeps removing the aluminium oxide layer.

The only remidy to this problem is to keep the blower on without the compressor for a while before switching off the AC. This lets the condensor reach room temperature before the air flow is stopped.

Please note that this takes years and is more pronounced in humid environments.

Last edited by drpullockaran : 24th January 2010 at 17:22.
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Old 24th January 2010, 17:19   #4
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Quote:
Originally Posted by Leop View Post
Firstly the condensor is the part of the AC that gets cold and has air blowing through it. It is usually located inside the dashboard.

The condensor is usually made of aluminium and is made of a very thin gauge to aid in heat exchange.

During normal AC operation the condensor gets very cold and the air blows through it. The problem starts when you switch off the AC or more specifically the blower. The instant the blower is switched off, air stops flowing through the condensor. Howerver the condensor is still quite cold. Due to this water starts to condense on the condensor. Much like on a cold bottle. This water causes the condensor to corrode over time.

Most people thinlk aluminium does not corrode. This is not entirely true. Aluminium forms a layer of aluminium oxide over it which helps to prevent corrosion. The problem with the condensor is that the air blowing through the condensor keeps removing the aluminium oxide layer.

The only remidy to this problem is to keep the blower on without the compressor for a while before switching off the AC. This lets the condensor reach room temperature before the air flow is stopped.

Please note that this takes years and is more pronounced in humid environments.
Edit-Find Condenser Replace Evaporator Replace All - Like Rancho replaced Chamatkaar with Balaatkaar in Chatur's speech

What you have just described is the evaporator coil.The condenser is the one next to the radiator which condenses compressed refrigerant

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Originally Posted by Leop View Post

The only remidy to this problem is to keep the blower on without the compressor for a while before switching off the AC. This lets the EVAPORATOR reach room temperature before the air flow is stopped.
Agreed;I have been following this for several years
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Old 24th January 2010, 22:39   #5
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Quote:
Originally Posted by drpullockaran View Post
Dear Leop,
please replace the word Condenser here in your article with "Evaporator". The condenser is the radiator like thing that sits in front of the engine radiator. Its jobs is to condense refrigerant gas into liquid from the gaseous state. The Evaporator is the part that goes cold up to about 1 to 2 degrees Celsius which is situated in the passenger compartment. The function of the evaporator is to take heat from the passenger compartment to evaporate the liquid refrigerant that has been liquefied earlier by the condenser with help from the AC compressor.

Next point that is amiss is that it is impossible to blow of the aluminum oxide layer with the strongest of air blowing over it neither can one wash of the aluminum oxide layer with the strongest of water jets. Chemical treatment is the only option for removing the oxide layer and that too in an inert environment.
Thanks drpullockaran, my bad I know this. Posted during a working Sunday. Will be more careful next time.

I know aluminum oxide is really hard to remove, so I agree with your skepticism on this. This is what I was told by a number of AC mechanics. Is it possible then that condensation on the evaporator does not affect it?
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Old 29th January 2010, 23:13   #6
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Default Any acidic fluid condensate will affect the Evaporator fins.

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Originally Posted by Leop View Post
Thanks drpullockaran, my bad I know this. Posted during a working Sunday.Is it possible then that condensation on the evaporator does not affect it?
Yes definitely the condensation will affect it especially when mixed with diesel exhaust fumes and other pollutants that come into eventual contact with the Evaporator fins however good be the air filter that might be there in the AC unit. Most cars do not have the air filter. Your advice is very good and drying up the Evaporator before shutting down the car is perfect. Thanks and I will make it a point to follow your advice.
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