2012 Volvo S60 - Lurches

After stopping at a traffic light, my transmission seems to lurch or buck when I let my foot off the brake pedal. This is an intermittent problem, but seems to happen more frequently in hot weather with the A/C on. What could cause this?

Are you sure that this is a transmission-related problem, and not an engine-related problem?
More than likely, the engine is hesitating, and the probable cause of that symptom is a dirty throttle body.

But, just to dwell for a moment on transmission issues, I have to ask…
Have you checked the level, color, and odor of the transmission fluid?
How many times has the trans fluid been changed? After 7 years, the fluid should have been changed twice, so far.

Sometimes when I let my foot off the brake on an incline. I roll backwards before the transmission engages.

The design of virtually all “modern” automatic transmissions allows for “rollback” on a incline, and that situation–in and of itself–does not indicate a transmission problem.

What about these questions that I posed earlier:

I asked the at the dealer about checking the transmission fluid cause I could not find the dipstick. They said it has a sealed transmission and of course it never acted up when they test drove it

Again, has the fluid ever been changed?

That would be a great place to start.

It might well be sealed in terms of not having a dipstick, but it is definitely not sealed in terms of being able to change its fluid. Even though I still think that you should start to try to resolve your hesitation problem by cleaning the throttle body, I strongly suggest that you have the trans fluid changed if you want to get a few more years of use from that transmission.

The transmission fluid is cooled with the engine coolant, and keeping the engine coolant temperature under control is more difficult with the AC on. I expect whatever the problem is, it is caused b/c the transmission fluid is getting hot. The first step is making sure the engine coolant temperature remain in spec even on hot days with the AC on. If that’s ok the next step is to use compatible scan tool to check for transmission codes. Still nothing found? Next then is a proper transmission service. How that is done depends on the car’s design but usually includes cleaning the bottom of the pan and replacing the transmission filter and always includes replacing the transmission fluid with fresh, and verifying the fluid level is spot on.