Is it normal for cold air to leak out of the evaporator coil cabinet?

Sealing those gaps was acutally a smart move. That air blowing out is called "bypass air," and it's essentially conditioned air that you've paid to cool wich is now cooling your basement or utility closet instead of your living space. While the amount of air leaking trough those small penetrations around the copper lines and PVC drain isn't enugh to kill your system, every little bit helps when you're trying to baby an older R-22 unit like that Carrier.

The only real risk with using standard silver duct tape is that the adhesive tends to dry out and fail over time due to the temprature fluctuations and condensation on the cabinet. It eventually gets brittle and falls off. If you want a more permanent fix, look for a product called **thumb gum** or duct seal putty. It's a non-hardening clay-like material that you just smash into the gaps. It creates an airtight seal but stays flexible, so if a technician ever needs to move the lines or service the evaporator coil, they can just pull it out without a mess. You don't have to worry about causing drainage issues by sealing those specific spots. The condensate drain works on gravity, and as long as the internal pan isn't cracked and the PVC pipe itself isn't blocked, sealing the hole where the pipe exits the cabinet won't affect the water flow at all. If anything, it helps maintain the static pressure your blower motor needs to push air all the way to the upstairs vents.

Keep an eye on that Super Saver. Those old units were built like tanks, which is why it's still kicking after all these years, but keep your filters clean. Since R-22 is becoming incredibly expensive and hard to find, keeping the airflow optimized is the best thing you can do to prevent the compressor from straining. You're definitly on the right track by tightening up the cabinet.

While you're at it, check if that 3/4" PVC drain has a proper P-trap installed. If it's missing, that old Carrier blower is likely sucking basement air right up trough the condensate line, wich kills your efficiency just as fast as those cabinet leaks. Those Super Savers are ussually paired with a beefy A-coil, but they're magnets for pet hair and dust. Grab a can of Nu-Calgon Evap Foam and give the fins a once-over. Keeping the static pressure within spec is the only way that R-22 setup is going to survive another record-breaking summer. If the coil is clean and the cabinet is tight, you're golden.

Don't sweat the tape for now, it's better'n nothing. I've got an old unit too and found a bunch of leaks around the plenum joints using a stick of incense. If you're relly bored this weekend, grab some foil tape—the stuff with the peel-off backing—and go to town on any seam that feels breezy. It sticks way better than the cheap silver cloth stuff when things get damp. Just don't tape over any access panels you'll need to pop off for filter changes or you'll be kicking yourself later.