Hey guys,
I am no HVAC guy. From what I understand, Car AC works differently than home AC systems. In-home AC systems the thermostat cycles the compressor on/of but in the car it doesn't seem to work this way. Correct?
My question is what causes the compressor on/off cycle in my LS 430.
Does leaving the AC at max cold with a lower fan speed better for the compressor or a higher temperature with max fan speed.
From what I understand, if you set the AC at a higher temperature the car will mix hot air from the car heat system/outside air to get the desired temperature. Don't you think it is bad for the compressor as it always needs to work as you are adding hot air to the system?
Sorry for my english

 

Car AC works the same way. The Compressor has a clutch on it that is controlled by the electronics.
The system in the LS430 is a Climate Control system so it will switch on the compressor if cooling is needed and switch it off if cooling is not needed.
Heating the inside of the car can be done either via pulling in outside air (if it is warmer outside) or by using the cars heating system (if it is colder outside the car).
In Auto/Auto mode it's all handled by the Climate Control system electronics.
If you manually override the system then you will be making the system less efficient, but some people prefer it that way.

 

Are you sure it works like the Ac at the home because when I set the temperature at max cold in the car the air is cooler than if if set to 21C.
Also I don't see a temperature sensor inside the car where it check the ambient temperature to cut off the ac

 

My 02 has 238k on it......just set it to what you want and forget it. I have not seen an issue with these cars compressors virtually ever.....it has 3 sensors I think depending on trim, left, right and rear. All of them have the front two

 

That's what the blend door is for. The "fully" cold air from the compressor is mixed with the hot air from the heater core to put out the desired temperature.

The interior ambient temperature sensor is next to the driver's knee behind the small louvers in the dash.

I figure the compressor is either running or it's not, don't think the LS430 has a variable AC compressor.

 

The compressor running is pretty much automated and consistent with whatever the temperature may be set at, mainly to assist with dehumidifying the interior. Even if the heat is all the way up, it still will kick the compressor on as needed, so long as the A/C is set to on, or if it is on any front defrost mode.

The main difference between household and automotive HVAC systems, as WILLYumD said, is that cars have blend doors to combine the warmth of the heater core, with the cool air from the A/C evaporator, where as houses do not.

Houses in the other hand, will either run the A/C, or the Furnace at 100% until the desired thermostat temperature is reached, then will turn off the required system until another call for service is requested by the thermostat.

The main harm that comes to air conditioning systems is when they aren't run AT ALL during the wintertime, and then the seals dry up and start to leak due to no oil recirculation.

 

I actually think it does use a variable system, not 100% sure but I remember looking into the car before I bought it to factor in parts costs and I was surprised by compressor cost and found out it was a variable system. I could be wrong but I do remember something about it...

In winter the AC still works to defrost or if you command it manually, you won't have an issue with it 99.9% of the time.

 

The '01-03's use a clutched system, the '04+ use variable output compressors.