built a fence around it just make sure its open chicken wire or to that effect so the unit can breath.

I had time to think about this today. The line set is curved from the unit to the hole in the wall, so a metal covering is more difficult. I have some thin aluminum flashing rolls that I may cut into strips about 2" wide and use that as a wrap for the insulation. With overlap, each turn should cover an inch or so and conform to the curve reasonably well. It will require some work to install. But the aluminum must not touch the copper in any way.

Bus, look for metallic adhesive tapes, available in aluminum and stainless.
Some have an intermediary foam layer.

Pretty sure McMaster-Carr carries them.

If the stuff Aphonse is recommending is thick enough, go for it, but I suspect it won't be. I like your idea of flashing rolls, but you're right, you must completely insulate it from copper contact.

Another thought - if this would work, what about rigid or flex pipe (like drainage pipe) that you could split and slip over the lineset (with rigid, cut a strip out of the side) then fill with sprayfoam?

I used to have what amounted to metal guttering wrapped around the exposed part of the lines. The guttering was painted.

"what about rigid or flex pipe (like drainage pipe) that you could split and slip over the lineset". Thought provoking suggestion. Thanks.

Kind of OT, but I caught 5 raccoons in a live trap this week. I set it behind my garage and got two pairs and a single. I am after feral cats, but the raccoons area a PITA too. This is an urban environment in a single-family home neighborhood. If things slow down, I might think that I've made a temporary dent in the population.

YW re the pipe idea. Maybe you could also build a box to enclose it, if that didn't look too weird? If the pipes run hard up against the house you could just build an enclosure, and stuff it with insulation - screw a cover on, for future access.

Ionized, re the Feral Cats, I hope you are able to take them somewhere to be humanely euthanised. Feral cats are a pest. IDK what to say about the Raccoons! They are cute, I have to say. Tell the neighbours to lock up their trash?

I live on 47 acres with probably more acreage than that undeveloped and contiguous. Raccoons are often found to have rabies in my area and they riddle a corn field. They also can be about the most fierce fighters if they feel threatened.

The above mentioned metal tapes are around .003" thick and with overlap won't be tasty to your varmints. The foam layer would act as dielectric if you were in doubt.

But the loom idea sounds pretty good. Maybe an electrical supply or again, McMaster.
No, I don't own the company, have stock, work there, or get a catalog.

And it could be mice. A non-chewable wrap is about all that will stop them. Fencing mesh would need to be extremely fine and tightly fitted everywhere to keep mice out.

The neighbors put food outside for the cats and the raccoons waltz up and eat what they want too. The raccoons can do a lot of damage. I have an associate that is pretty hard-line abut the cats -- They eat songbirds, they are an introduced species so shoot them. (She has a wildlife and fisheries degree.)

The cage is on loan from the local animal controls dept. They take the cats and the raccoons. They handle the cats themselves. I suspect the state wildlife dept. takes the raccoons off their hands.

Fortunately, not much rabies here. I have never understood why the distribution is not more universal in North America. Coming from NY, I understand the problem. A couple of years ago a friend of my mom's, who lives in Tompkins Co., was bitten by a rabid fox that ran up on their deck in the middle of the day.

Wow. We are very lucky that rabies doesn't seem common at all in the west (BC) - and we can now innoculate our pets.

It now looks as if the problem is weather exposure and especially ultraviolet light. The control cable is taped to the lineset and is not chewed at all. Not typical of gnawing animals to ignore such as the control cable. I replaced the insulation on one of the linesets and need to get another length of insulation for the other set.

Metal jacketed line insulation is available, but it sees most of its use on commercial rooftops in desert type areas with a LOT of sun.

I can't believe all these responses to one simple question. I would like to witness this guy raccoon proofing his unit. Good luck.

The replacement insulation is now in place. The other was just weathered away here in central NC. I found one visible marking "Insul Tube 180" is what it appears to say. The material inside the house looks perfect.
The link gives a clue that the UV resistance is limited.

Here is a link that might be useful: Insul-Tube