My evaporator coil was recently replaced (Carrier CNPHP6024ALAAAAA replaced with a bigger unit, CVPMA6124XMC). They sealed around the edges with tape. The original install was sealed with some kind of sealant putty? not sure what it is called. Also, the outside pipe was originally covered with some UV resistant white tape. Looks like it was just left cut open and not repaired. Should I fix these issues or leave it be?

pics of install: https://imgur.com/a/k7LMmDY

couple questions:

  1. I can feel some air escaping around specific areas where the tape is. Should I remove the tape and seal with putty? What do you guys recommend?
  2. since a bigger unit was installed, seems like the drain pan is no longer big enough. Should I replace this with a bigger pan or will this be ok?
  3. Also, noticed some mold around the ducts. Does this need to be remedied or is it ok?
  4. What should I be looking for to see if the install was done correctly?
  • It sounds like the original work was not completed, so get them back to finish.
    – crip659
    Aug 13, 2023 at 19:50
  • "Seems like it is taking much longer to cool down." - are you comparing it to last year when it wasn't 110f on average?
    – Mazura
    Aug 13, 2023 at 20:18
  • W/o a gauge set that has superheat and subcooling, a recovery tank, a tank of 410, and (hopefully not) a vacuum pump and a good lineset that can draw past 500 microns, there isn't much you can do.
    – Mazura
    Aug 13, 2023 at 20:37

2 Answers 2


duct mastic - installers use tape on the equipment to facilitate replacement. You can do w/e. But please don't. All the swearing at the beginning was because of that and why it sounded like they were using a hammer and a chisel to get it lose.

Pans big enough don't readily exist for horizontal installs?

Ducts outside the envelope need insulation or they condense and grow mold, especially if they leak. Pull the insulation back and tape the duct. Put it back and then tape that too. Then put self adhesive insulation on the exposed plenum chamber.

Surface prep for tape or adhesive is rubbing alcohol. If the house didn't reek of that, that's why the tape's peeling.

On a new install this would be horrible. But for a coil swap, your ductwork isn't on their docket. They used tape on the machines instead of mastic? Thumbs up.

  • Tape there is actually the one thing I can take a glance at and know that these people do this every day. And the fact that it's back into any sort of working order.
    – Mazura
    Aug 13, 2023 at 20:23

Kill the Mold,

The drip pan has a drain and as long it is working you are ok.

There should be a drip pan overflow sensor –

There is usually no UV in the attic, but you can add tape over existing one

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