Car AC Which is Better Thermostat or Fan Speed Control

very good advise..GA

You don't live in AZ

If you run fan speed at max continuously they tend to burn out that speed, so my advice would be not to run fan at max speed or second highest for extended periods of time....for efficiency the controls should match the heat load, initially both on max then drop fan setting when desired temp is reached, then adjust thermostat to comfort....

max cool will run your compressor at max

max fan will run your fan at max.

Your compressor takes considerably more energy than your electric fan...

Ultimately it's all about your comfort level... in the end... who cares?

The compressor in your vehicles AC system cycles on and off based on the pressure in the low side of the system. At high engine RPM's the cycle times are short and at idle they are long but the overall energy used over any period of time is about the same.

What all of this means is that for the most part it does not matter where the controls are set being they system uses the same average energy from the engine regardless.

Also with most vehicles the AC MAX setting just recirculates the air from inside the cab opposed to taking warmer more humid air from outside the vehicle. The actual energy used by the system is still the same.

Fan is used for distribution of cool air. Sometimes high fan speed will create noise and uncomfortable in addition to more energy consumption. Keeping the thermostat at maximum cool position will consume more energy. Optimum is to keep the thermostat in middle position and fan according to the comfort level of passenger. You can adjust air throw position as per your confortable position to compensate the fan speed.

I am with #4 and #5 (plus the funny ones), firmly.

Additionally, the temp. control mixes warm air from the cabin heater (?!?) in most cars, as compressors do not like rapid on/off cycles. Bad for efficiency.

Low fan speeds are inadviseable, as the heat exchanger will freeze up in rain. Not a good idea.

Max. cool (recirculate) keeps the moisture to be removed to a minimum. This is the best way to keep your windshield from fogging up. If you cannot see, how do you do drive?

The thermostat only mixes warm air with the cold air. No savings available there.

The fan motor is fed full voltage on high, and just reduces the voltage on the lower speeds by heating up a resister first. No savings there either.

Just stay home and soak in the pool. No gasoline used. No money spent.