can't feel AC engage anymore...

[JHZR2]

Hi,

Usually (i.e. in the warmer weather), I could turn on my car, turn on the 'econo' fan, and then switch to the AC settings, and feel and hear the engine have a little more load. Lately, I have not been able to notice this... I like to run the AC a bit when starting from overnight to increase the load a bit to help it warm up (Im freezing anyway, so it doesnt really matter), but really arent sure that it has been going on.
I know that it is cold and that the AC cycles depending upon desired temperature, however, I keep it on 'min' temperature, which according to my manual ought to keep the AC compressor constantly cycling on and off, regardless of cabin or ambient temperature.
Is there any good ideas of how to diagnose this? It doesnt work for either of the AC settings that are between the econo button and the defrost one.

Second question... when starting cold after sitting overnight or longer, I will occasionally have the car misfire a few times immediately after startup. I glow once, and the car will catch immediately after turning the key to the start position, no need to crank it at all. All the glow plugs appear OK via the resistance test. Would it still be wise to replace the glow plugs? Its odd that one cyllinder must be misfiring, when the engine starts really good, even at 12°

Thanks for the help,

JMH