Is my DIY dual hose mod actually supposed to run this hot?

That extra heat on the casing is a massive red flag that your compressor is struggling to breathe. When you move from an open intake to a restricted DIY plenum, you're dealing with a major drop in static pressure. A six-foot flexible hose, especially if it's the corrugated kind, creates a ton of internal friction that slows down the airflow. If the air isn't moving fast enough across those condenser coils, the heat stays trapped inside the unit instead of being dumped outside, which explains why the plastic shell feels like it's baking.

You really need to check the surface area of your intake port versus the original vent. Most of those portable units have intake vents that cover nearly the entire back half of the machine. If your cardboard shroud only funnels air into a single 5-inch or 6-inch hose, you've effectively choked the machine's cooling capacity. You're basically forcing the fan to work twice as hard to pull in half the air it needs. To fix this, you should look into a **larger diameter duct**u2014think 8 inches if you can fit itu2014or even a dual-intake setup to maximize the volume of air reaching those coils. Another thing to watch for is the seal on your cardboard box. If there's any air leaking from the room back into that intake box, you're just recirculating air, but the main issue is usually the restriction. If you keep running it while the casing feels hot to the touch, you're going to trip the thermal overload protector on the compressor or, worse, significantly shorten its lifespan. I'd also suggest insulating that exhaust hose if you haven't yet. Since you're now pulling in 95-degree air directly from outside to cool the coils, the exhaust is going to be even hotter than usual. Simple **reflective wrap** or even a thick towel around the hot hose prevents that heat from radiating back into the room you're trying to cool. If the unit continues to run hot after widening the intake, you might actualy need an inline booster fan, but usually, just increasing the duct size and keeping the run as short and straight as possible does the trick.

I ran into the same heat issue when I used a flimsy box. The suction was actualy pulling the cardboard inward and blocking the fins. I swapped it out for a plastic dish tub and used foil tape because regular duct tape just peels off when it gets that hot. Another thing—check the window end of your intake. I found out the hard way that without a screen, you'll suck in every moth and piece of dust in the neighborhood, which gunks up the coils fast. Adding a simple mesh pre-filter on the window side saved my compressor from choking out.

Spot on about that static pressure loss. People relly underestimate how much those ribs in the flexible ducting kill the velocity. I'll add that you shold double-check the bend radius where that intake hose meets the cardboard plenum. If you have a sharp 90-degree turn right at the box, you’re creating a massive air vortex that essentially blocks half the pipe. Try to use a rigid elbow or at least smooth out that curve with some wire support. Even if the hose is wide enugh, a pinched neck at the entry point will choke the compressor just as fast as a skinny duct that's too small.

Are you sure the heat is acutally from the motor working harder? Have you ruled out the possibility that the casing is just warming up beacuse you're now pulling 95-degree air trough it instead of 75-degree room air? Before you go buying a bigger hose, maybe check if the air coming out of the exhaust is significantly hotter than it was before the mod. If it's just the plastic feeling warm, it might just be heat transfer from the intake air itself. Is the unit actually cycling off once it hits the target temp, or is it running non-stop now?

While the previous points regarding static pressure are mathematically sound, I suspect you might be overlooking the specific heat capacity of the ambient air currently being introduced, as shifting from 75-degree indoor air to 95-degree outdoor air for condenser cooling necessitates a significantly higher mass flow rate just to maintain the same thermal rejection efficiency. If your cardboard plenum is even slightly undersized relative to the surface area of the original intake grilles, you are essentially inducing a vacuum effect that increases the compressor's discharge pressure, leading to the elevated casing temperatures you’ve observed. Have you verified the amperage draw with a clamp meter to see if it's exceeding the nameplate rating during these peak 95-degree periods?

Quick update — you guys were right about the suction. I checked and the cardboard was definitely bowing inward. I swapped it for a rigid plastic bin like suggested, but the casing is still pretty hot. One reply mentioned the 95-degree intake air vs room air, which makes sense, but now I'm wondering if I should just use a shorter, smooth-walled pipe to help with that static pressure?