The answer seems to be "it depends". Given the commerciality and competitive nature of the HVAC industry, I had a lot of trouble finding peer reviewed academic studies that test your claims. Therefore, I took a look at the patent records for evidence, which led me to US Patent #5492273. This patent, owned by General Electric, describes a variable-speed blower that can be controlled independently of the compressor. Here are some claims made in the background section of the patent:
In general, total heating of air conditioning capacity of a system increases as the indoor air flow rate increases. However, upon reaching a particular air flow rate, the blown air will be less warm or less cool, depending on the mode of the HVAC system, than the air in the room. For air conditioning systems, the indoor coil, or evaporator, tends to "saturate". In other words, the the coil extracts incrementally less energy from the air for equal incremental changes in air flow. Further, the electric power consumed by the indoor blower motor increases rapidly as the air flow rate increases. The system dissipates electric energy as heat in the same air that is being cooled by the system thereby reducing its net cooling capacity. Due to the effects of coil saturation and blower motor power consumption, net total capacity peaks at a certain airflow rate.
Let me briefly summarize the salient points of that paragraph before continuing:
- For traditional, single-blower-speed air conditioning systems, the efficiency of the system does not scale linearly with air flow speed.
- The blower motor's electrical usage scales superlinearly with respect to air speed.
- The faster the air speed the more the coil heats up, thus reducing its cooling efficiency the next time the condenser turns on:
an increase in the air flow rate beyond what is required warms the evaporator coil to produce a higher load on the compressor motor.
The patent goes on to explain that the reason why most traditional, single-speed blowers don't keep the blower on after the condenser has turned off is exactly because of point #3: The airflow will heat up the coil and require the condenser to remain on longer during the next cycle. The patent also claims that some traditional systems try and avoid this by only switching off the compressor when in blower-only mode (i.e., also keeping pumping the refrigerant), however, the patent says that that uses almost as much electricity as running the entire system:
Conventional systems ... [delay] turning off the indoor blower fan after after the compressor cycles off. However, the system also continues to draw power at the same level as during the cycle and causes additional energy to be consumed in the indoor fan motor.
[Emphasis is mine.]
This claim is a bit surprising. The patent could of course be embellishing that claim in order to make its technology seem more useful.
The patent describes a variable speed blower motor that can work independently of the condenser to set the air flow to the optimal speed for cooling. The thermostat, with information from both indoor and outdoor temperature and humidity sensors, can then intelligently decide how to control both the blower and the condenser.
Therefore, I'd say that if you have one of these variable-speed blowers and intelligent thermostats (they're getting more common now; I have one in a house I recently bought), I'd say that it would be a bad idea to force the blower to stay on all the time because the system is smarter than you! If, however, you have an older, single-speed system, that question is a lot more complicated, and it might actually be detrimental to run the blower all of the time.
