All, I have been driving my 2003 Ranger 2WD Automatic XL with LB for about 15 years now. In the last couple of months or so I noticed that when I am accelerating with the AC on that the cold air coming from the vents decreased drastically until I am back to cruising or back off the gas. I don't know why I had not noticed this feature before but it is very obvious now.

I would guess it is cutting off the compressor during acceleration to give the engine all the power it needs during acceleration. However, have I been asleep all this time and never noticed this feature?

Additionally, when I am driving behind a diesel truck I am able to smell the exhaust coming thru the vents despite the fact that I have my AC set to MAX, which should at that setting be on recirculate and not allowing outside air from the vents to enter the cabin.

So my questions are:
For the decrease in cold air during acceleration, Is this an indication that I am running low on Freon or is this by design? Have I been driving all these years oblivious of that feature?
For the smell of fumes, is there a cabin filter on that year ranger that's been neglected all those years?

Thanks,

 

All the vents, defrost, panel, floor, and outside/inside air are all run by vacuum "motors"

So it reads like you have a broken/leaking vacuum line in engine bay(no not a vacuum leak in engine) or your Vacuum reservoir is cracked

Look on passenger side of engine bay at firewall, right next to fender you will see a Black and a Grey hard plastic vacuum line coming out of firewall
Grey one goes to heater hose by-pass valve
Black one runs along the frame to the front and to the Vacuum reservoir, this black line can be damages by exhaust heat, check it

Engine supplies vacuum to vacuum reservoir, same as it supplies vacuum to power brake booster(its a vacuum reservoir too)
The vacuum reservoir holds vacuum level in cab the same when accelerating as engine vacuum drops
So either vacuum reservoir is leaking or the line going into cab is, so it can only provide steady vacuum when engine has higher vacuum

Feel defrost vent when accelerating, if air flow is shift to defrost vent then its for sure a vacuum issue, defrost is the default(no vacuum) vent direction

 

Thanks RonD, I will check it out and let you know my findings.

 

Following RanD's advise I looked in my engine bay and discovered that the gray hard vacuum line was not connected as it draped over the area of the passenger side valve cover. The 90 degree elbow had come off of the heater valve. I reconnected it and all is well again.

A Big Thank You to RonD for his guidance and help. It's Great to have such a helpful community. Much appreciated!

 

Good work

Thanks for the update