Both my 2015 and now 2020 have this random issue. Sometimes when getting the truck started and the AC coming on, sometimes it comes on with a "boost" of harder air coming out the vents. You can hear it from under the glove box, but sometimes, now more often than not in my 20, it doesn't have that boost coming out. I used to be able to get it to come on by cycling the power to the AC in my 15, but it just seems to not do it other than just randomly in my 20. Being in the deep south, I like it having that boost of air on all speeds. It just seems to come out colder than without. Is this just programmed into the computer programming of how it works, or is this a faulty fan motor or something else??

 

If you turn the temp **** all the way cold it will go to max ac.

 

Manual or automatic climate control?
Most vehicles now adjust the blower speed after a start and it's usually ambient temperature based.
Don't know if you use bluetooth or voice commands but even the manual control ones turn the fan down for noise control when using voice.
Like if it's really hot it doesn't try to blast you right off with hot air, and if it's really cold it doesn't try to blast you right off with cold air.
Even my 2005 model Dodge has "auto warmup delay" so if the temp is set to auto AND it's cold AND the setpoint is a certain amount above ambient, it will just dribble air until it can supply warm air.

 

That sound you're hearing under the glove box is fan noise from the open recirc air intake. Your air conditioner is going into recirc mode, probably as a result of being set to Max AC either by you or automatically due to ambient temperature. It's due to some input the system is receiving, not random.

 

Are you set to "auto?"

 

When I get in my truck, it's set almost always to max and recirc. It's very hot here in south Louisiana and south Texas and only after my cab cools, will I turn the temp up to 65. My thought would be it should be kicking on immediately but it doesnt.

 

I live in the deep south, its almost ALWAYS turned to max cold temp...

 

I usually have on manual. But have had it in all regimes, settings. It's almost completely random.

 

Not sure what you're describing here. What isn't kicking on immediately?

My truck has remote start, and when I start it remotely (which is mostly in the hot part of summer), the air conditioner comes on, but I've noticed my automatic system doesn't go into Recirc mode until I get inside and turn on the ignition. Maybe this is what you're talking about. My understanding is, when the AC first comes on with remote start, it's drawing in outside air to displace the hot air inside the cab (which is hotter than the outside air under most conditions). It will switch to Recirc after the interior air starts to get cooler than outside. This is the quickest way to cool down the cab.

 

UPDATE..... It's the blower not coming on intermittently. Sometimes I'll bang on it underneathe the glove box and sometimes it'll kick on right afterwards. I can't figure though, to replace the blower motor or the blower motor resistor. I would think it's the resistor seeing that the blower will come on intermittently indicates the blower does work.