anyone notice....

if you have the recirc button off, and any speed above 30 its like having your fan speed on the first setting even when fan switch is in the off posn? if I turn the recirc button on the air flow stops, kinda handy if your fan ever fails

At idle in gear at at a traffic light if the AC is on or the selector is in defrost, you get a idle surge enough to make you think the truck moved forward??

 

The truck will increase its idle when the AC is on due to the AC compressor being engaged and putting an extra load on the motor.

 

thanks, Im aware of this,(mechanic 30 yrs) but this is the first veh I have owned that ever wanted to "lurch" when the AC cycles, was curious if this is normal for other trucks as well?

 

Coworker had a Colorado that did the same thing.

 

Ok, so then the answer I'd say is Yes. Mine does the same thing, including my fathers 1st gen and 2.5 gen tundra. Might be a toyota truck thing?

 

Yes, the A/C lurch on these trucks is rather pronounced.

 

Mine 3rd gen doesn’t lurch ever..neither did my 2nd gen.

 

my 2nd gen lurches but I've never felt it like this in any other vehicles I've owned. good to know it's not just me though

 

My 2015 4.0 V6 never surges.

 

I think it depends on how tight you're holding the brakes at a stop. I tend to let up on the pedal after I stop so the brake is barely holding (let the heat dissipate) and I notice the lurch. Under normal circumstances (a solid hold of the brakes), I dont.

 

Well, when did recirc (some call it 'max air') become a thing? Early to mid 70's? Maybe a little later? But yea, non recirc (some call it 'vent') has worked like this since then. Some vehicles just do it better that others because of the way the fresh air intake in the cowl is configured.

Common in lots of small displacement auto trans vehicles. Do you have a 2.7 auto?

 

Yup its normal, my truck has the lurch as well.

 

In all the trucks I've owned, this is the first truck that will lurch forward when the AC cycles. When stopped at a red light and it happens, I just apply a little more foot pounds on the brake pedal.

 

The stall on the torque converter has a part in this.... 1st, 2nd and 3rd gen tacos all in my experience seem to have rather tight torque converters (compared to bigger full size trucks i have driven), this makes it so that the bump in rpms with the AC kicks on is felt more.

 

2015 4.0 V6...yea, this truck hates when the AC kicks in.

 

thanks to all that responded, good to know I wont be spending time trying to solve an issue, that likely is unfixable

 

Another lurcher here.

 

Recirculation off means flow-through on. It makes sense that you'd get airflow from the vents when at speed, with recirculation turned off.
Yes the IAC valve adjusts the idle speed for the increased load from the AC compressor but it's supposed to equally compensate and maintain the same idle speed, not actually increase the idle speed. Doesn't seem right that it lurches when AC is turned on or off. Maybe the system isn't timed correctly? Meaning, when AC is turned on, maybe the IAC increases the idle speed before the compressor clutch engages? And maybe when AC is turned off, the compressor clutch disengages before the IAC rolls down the idle? That's all I can imagine that would cause this.

 

This is the only Lurch I know of...”you rang?”