We have two water handles to our Grohe shower fixture-the upper one controls the shower head the bottom one controls the faucet. If someone turns the faucet handle on at the same time the shower is turned on I believe an air bubble is created so the faucet handle no longer is operable. My question is, how do I release the air bubble so I can get the faucet handle to work. Thank you.

No such a thing as "air bubble" preventing your faucet from working the way it was designed to work.

You have to be little more specific in your description.

1. "Faucet Handle" = volume control or temp. control valve ?
2. Is this shower only faucet ?
3. Model # ?
4. Perhaps you could snap a photo of it and post it for us so we can ID the faucet ourselves ?

Back to you...