Shudder and "Jump" when A/C is cycling?

If you have the brakes applied you can stand on the throttle till the engine stalls and it won't move.

Suspect any 'lurch' you feel (which certainly can be real) is driveline slack being picked up. Making the body have some motion, but the actual wheels are not turning.

If the wheels are turning based on AC idle step up, you either need to press the pedal a bit harder or fire your brake mechanic.

As a ghetto fab solution you can either turn off the AC or put the vehicle in neutral at stops.

 

Thought I'd been rear ended so many times when I was not used to this lurch "feature"... hah

But truck should not actually move. Feels like it, but brakes hold while suspension allows flex. Push the pedal harder if you're actually moving...

 

Yeah. Sometimes it feel like someone rear ends your truck

 

Um, the defroster has only ever been on once, I can assure you that, and that was one time when I went up to Mount Charleston and it was snowing heavily. Living in Vegas, the A/C is on about 85 - 90% of the time, more like 95% these last few years. Heater is only ever driving on cold nights during winter when it gets below freezing, but that's it. Yesterday my temp gauge read 105 in the sun at the Kobalt 400, mind you it had been sitting for long, and this entire week is high 80's with direct sunlight reaching 110 estimated.

 

Exactly, thats why I dont want to actually bump someone in front of me because the A/C kicks in so hard it moves the vehicle under braking.

 

The AC engages the clutch fan also, I was answering someone who said it happens when his AC is off.

 

Ah got it, thought I saw my user name not his.

 

That's strange man. Wonder why the truck is actually moving.

 

I had this problem as well as sometime a little bump feeling when coming off the brakes at a stop light. Turned out it was the axle preloading due to weak leaf springs. never had the issues again after the TSB (recall) springs were installed.