It is not ok to leave them open to suck in unflitered air and upset the air balance of your system. It is not something that has to be fixed immediately, but it needs to be fixed. It is an important task to be accomplished but not urgent. Do not repair with duct tape! Duct tape is not for air ducts. Use the correct material and masticks for the repair. If not certain what to use ask at your local hardware supply store. Check and replace filters at the airhandler because they are probably filthy dirty. Check and replace as needed air return filters while you are at it!
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OPTIMA CAR BATTERY, REDTOP -- BCI group 35, 12 V, 720 cranking amps at 0 degrees F, 910 cranking amps at 32 degrees F, 9-5/16 x 6-13/16 x 7-5/8 in. tall, 31.7 lbs., SAE post, 90 minutes reserve time, AGM battery type; A starting battery with performance power; Delivers the strongest 5-second ignition power for a reliable start-up every time