Air Con reluctant to cycle on and off

[philpreston3072]

I just bought a 2007 Tarago and noticed that on 25 degrees plus days, the Air Con compressor and fans seem to run non-stop rather than cycling on and off every 30secs or so.

Is this normal?  All the other cars I've owned the compressor and fans would cycle on and off, even when the temperature was in the 30s and 40s.  I think it's affecting fuel economy because I'm getting 13L/100Km whereas car reviews say it should get 10-11L/100Km.

Edit: I use Air/Con for the front and rear simultaneously.

Edited January 25, 2017 by philpreston3072
Add more info.

[trentmeyer23]

Long drives or traffic?

[philpreston3072]

Both.  Even on long drives, I can still hear the fans going when coming to a stop.  Switch the A/C off and the fans switch off.  Coolant Temperature is around 90C degrees so I doubt that is the reason for the fans going continuously.

[Hiro]

I'm fairly sure some cars run the radiator fan constantly whenever the air-con is on regardless of temperatures, to combat the extra heat being placed on the system due to the A/C condensor ejecting heat straight on to the radiator (since it is usually placed directly in front of it).

 

Might be worth checking exactly which fans you are hearing turn on and off, some cars have the air-con fan mounted on the front of the condenser (push-type) and others have a second one mounted to the radiator next to the radiator fan (pull-type)

[trentmeyer23]

As Hiro stated, there is a good chance that this is part of the design.

Cooling a cabin area that large puts a lot of heat through the refrigerant. The refrigerant needs to be cooled via the condenser which is located in front of the radiator in almost all cases. Due to the condensers location it relies on the fans when airflow becomes limited or the refrigerant temperatures are increased.

Is it the V6 or 4cyl?

[philpreston3072]

I have 4cyl.

[philpreston3072]

Just updating that my Air Con has been fixed and the fuel consumption is a much more satisfying 10L/100km when driving with Air con.  I can get around 540Km from a full tank and a full loaded car before the fuel light comes up.

The previous owner had overfilled refrigerant into the Air Con system which made the system too hot, resulting in the radiator fans constantly running on high on hot days.  So my mechanic had all the refrigerant taken out and then refilled with the proper amount.  Now when the Air Con is on, the radiator fans run briefly on a loud high speed before settling down to a quiet low speed which is so quiet you don't even realise the air con is on apart from a slight load on the engine.

It is true though that these new air con systems with variable displacement compressors don't cycle on and off as much as the older compressors.  They adjust to light compression once the air con system drops to the right temperature when cruising.  So the radiator fan does constantly run on hot days but should only run on quiet low speed when cruising and switch to loud high speed intermittently when stopped at traffic lights.

Those who are getting excessively poor fuel consumption with their Toyotas should test whether the air conditioning system is the cause.  Compare the fuel consumption between air con and no air con.

Edited April 26, 2017 by philpreston3072

[sanu kee]

On 4/26/2017 at 7:03 PM, philpreston3072 said:

Just updating that my Air Con has been fixed and the fuel consumption is a much more satisfying 10L/100km when driving with Air con.  I can get around 540Km from a full tank and a full loaded car before the fuel light comes up.

The previous owner had overfilled refrigerant into the Air Con system which made the system too hot, resulting in the radiator fans constantly running on high on hot days.  So my mechanic had all the refrigerant taken out and then refilled with the proper amount.  Now when the Air Con is on, the radiator fans run briefly on a loud high speed before settling down to a quiet low speed which is so quiet you don't even realise the air con is on apart from a slight load on the engine.

It is true though that these new air con systems with variable displacement compressors don't cycle on and off as much as the older compressors.  They adjust to light compression once the air con system drops to the right temperature when cruising.  So the radiator fan does constantly run on hot days but should only run on quiet low speed when cruising and switch to loud high speed intermittently when stopped at traffic lights.

Those who are getting excessively poor fuel consumption with their Toyotas should test whether the air conditioning system is the cause.  Compare the fuel consumption between air con and no air con.

Hi philpreston3072, just wondering where did you get the air con repaired from? I have having troubles with my air con and looking for a good mechanic. Thanks

[philpreston3072]

8 hours ago, sanu kee said:

Hi philpreston3072, just wondering where did you get the air con repaired from? I have having troubles with my air con and looking for a good mechanic. Thanks

I had mine serviced at Chang Auto in Springvale.  0410463580