Many forum users bringing up the topic about a/c cycling at idle (25 seconds on/ 10 seconds off). My car always does it at #1 & 2 fan speeds)
this can have many reasons and I will add 2 additional, such as:
old (not necessary dirty) cabin air filter and defective blower motor.
According to TSB 11-008 the motor may have problems including lower speed due to bad commutator to brush contact; lower air speed around the evaporator causes lower evaporator temperature and elevated high side pressure which in turn causes more frequent cycling and cool/ cold air coming from the vents.
The low cost remedy could be to use fresh air position, removal of cabin filter or running motor on 3rd speed

 

I think you are thinking about it too much. That's the way it's supposed to operate.

Think about the freon on the inside. The pump only has two settings, on or off. If the pump is going but the blower is not on full speed, you will have increasd pressure on one side of your system making it shut off. I'm sure the system has an over-pressure switch. Most do. If the fan is on high and it works fine, don't worry about it... Or remove some freon.

 

Cycling is normal. The lower the fan speed (and air flow) the shorter duration of the on part of the cycle. If at full fan speed it is cycling rapidly with short on cycles, then you are probably low on R-134.

 

In theory, to completely eliminate cycling (which wears a/c compressor clutch --- my biggest concern), the evaporator should be above 40 degrees F; this can be achieved by maintaining low side pressure above 34 psi.(Manual specks call for 19 to 45 depending upon outside temperature)
I miss R-12 systems

 

BTW, for Sanden compressors the Clutch cycling rate is less than 4 cycles per minute (per compressor manual).
Seems like I will put 1 oz of R134a to the system to see what happen.
I can tolerate some cooling loss that deal with major a/c repairs a year from now.
Will be hooking up my A/c gages and report!