I purchased my Jenn Air propane grill from Lowes over a year ago and have always been disappointed in the amount of heat it produced. It never reached over 300 degrees with all three burners lite. I just discovered only the left side of each burner lights with the spark ignitor, due to its poor positioning. The right side of each burner must be manually lite with a long stick, or the gas will leak out of the right side of each burner. I cannot believe this unit passed any safety codes, or has not blown up. The good thing is once you manually lite the second half of each burner it does get hot enough to cook food. I'm going to talk to Lowes about this, but I though anyone with a cold grill might want to know, and be aware that gas may be leaking out.

It sounds like your cross-over slit located underneath on the back of the burner is needs cleaning. Take your burner out, turn them over and your will see a slot on the rear of the burner. wire brush the slot until it has a clean slit. This cross-over slit is what brings the flame to the right side.

Thanks for helpful suggestion.