MRCOOL DIY 5th Gen 66 Ft. 1/4" x 3/8" Line Set for DIY 6K, 9K, & 12K Indoor (DIY66-1438-O)

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MRCOOL DIY 5th Gen 66 Ft. 1/4" x 3/8" Line Set for DIY 6K, 9K, & 12K Indoor (DIY66-1438-O)

Name: MRCOOL DIY 5th Gen 66 Ft. 1/4" x 3/8" Line Set for DIY 6K, 9K, & 12K Indoor (DIY66-1438-O)
Brand: MRCOOL
SKU: DIY66-1438-O
Price: 1241.0 USD
Availability: InStock
Rating: 4.84 (43 reviews)

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SKU: DIY66-1438-O

$1,241.00 $1,487.00

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BTUs

6K-9K-12K 6K-9K-12K
18K 18K
24K-36K 24K-36K

Lineset Length

16 Ft 16 Ft
25 Ft. 25 Ft.
35 Ft. 35 Ft.
50 Ft. 50 Ft.
66 Ft. 66 Ft.
75 Ft. 75 Ft.

In Stock Estimated delivery: Nov 14th-23rd

Only available for purchase with second MRCOOL product.

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Free Shipping*
30-Day Return Policy⁺

Package Overview

This line set is compatible with MRCOOL's 5th Gen DIY Condenser to the MR COOL 5th Gen Air Handlers with 6K, 9K, or 12K BTU.66 ft. line set is created by connecting a 50 ft. and 16 ft. line set with a coupler.Some assembly is requiredFor Multi-Zone systems, one line set per indoor unit is required to ensure the system will function properly.

Package Includes:

Description

Product Specs

Manuals & Guides

The MRCOOL 5th Gen DIY Line Set is a required component for installing your MRCOOL DIY ductless mini-split system. This 50-foot model is pre-charged with environmentally friendly R-454B refrigerant and works with MRCOOL's DIY 5th Gen 6K, 9K, and 12K air handler units, featuring 1/4” liquid and 3/8” suction lines.

Equipped with Quick Connect fittings, the line set allows for fast, tool-free installation—no vacuuming, charging, or special certifications needed. Built with durable, kink-resistant materials and a leak-proof design, it ensures long-lasting, efficient performance. Available in multiple lengths, it’s the key to making your HVAC setup truly DIY-friendly.

Series	5th Gen DIY Line Set - R-454B
Compatible Air Handlers	6K, 9K, & 12K 5th Gen DIY
Line Set Length	50 ft
Lineset Fitting Type	Quick-Connection
Gross Dimensions	37.2" D x 4.92" H x 37.2" W
Color	White
Color Family	Bronze/Copper Metallic
Refrigerant Type	R-454B
Refrigerant Volume (Oz)	6.07
Liquid Line Size	1/4
Suction Line Size	3/8
Registered Warranty	N/A
Has Batteries	No
Contains Electronics	No
Contains Chemicals	Yes
Contains Aerosol	Yes
Contains Compressed Gas	Yes
Proposition 65 Warning	Yes
Restricted States	GU;PR;VI
Net Weight (Lbs)	24
Gross Weight (Lbs)	29.5

Description

Product Specs

Manuals & Guides

The MRCOOL 5th Gen DIY Line Set is a required component for installing your MRCOOL DIY ductless mini-split system. This 16-foot model is pre-charged with environmentally friendly R-454B refrigerant and works with MRCOOL's DIY 5th Gen 6K, 9K and 12K air handler units, featuring 1/4” liquid and 3/8” suction lines.

Series	5th Gen DIY Line Set - R-454B
Compatible Air Handlers	6K, 9K, & 12K 5th Gen DIY
Line Set Length	16 ft
Lineset Fitting Type	Quick-Connection
Gross Dimensions	28.94" D x 4.92" H x 28.94" W
Color	White
Color Family	Bronze/Copper Metallic
Refrigerant Type	R-454B
Refrigerant Volume (Oz)	2.12
Liquid Line Size	1/4
Suction Line Size	3/8
Registered Warranty	N/A
Has Batteries	No
Contains Electronics	No
Contains Chemicals	Yes
Contains Aerosol	Yes
Contains Compressed Gas	Yes
Proposition 65 Warning	Yes
Restricted States	GU;PR;VI
Net Weight (Lbs)	7.9
Gross Weight (Lbs)	11.7

Description

Product Specs

Manuals & Guides

When one standard size DIY® QUICK CONNECT® LINE SET is not long enough, two standard QUICK CONNECT® LINE SETS can be combined using our DIY® COUPLER to increase the desired length of the QUICK CONNECT® LINE SETS.

Use this DIYCOUPLER if you have a 9K, 12K or 18K Air Handler. This also comes with 75ft of Communication Wire.

Dimensions	11"W x 22.5"D x 4.5"H
Unit Type	Accessories
Equipment Type	Coupler
Color	Copper
California Residents	See Prop 65 WARNING
Weight	6.39 lbs
Freight Class	92.5

Installation Manual

Build a Custom Mini Split

Click Here

*Shipping Policy

Free Shipping on all orders.
Large Appliances: Ship via Curbside Delivery — the carrier delivers to your property but not inside your home.
Small Items: Ship via standard ground delivery (FedEx or similar), such as small appliances, range hoods, sinks, faucets, and accessories.
See our Shipping Page for full details

⁺Return/Refund Policy

30-Day Return Policy: Return requests must be submitted within 30 days of your delivery date. We cannot process returns after this period.
Return Requirements: Products must be unused, uninstalled, and in their original packaging (including box and pallet) to qualify.
Restocking Fee: A restocking fee may apply and varies by brand. Please see our Return Policy Page for full details.

Browse MRCOOL Products

Perfect for our needs!

I ordered a 2 zone unit for the bedrooms in our home. It took a few months to arrive (manufacturer issue, nothing to do with HOD, and we were contacted on more than one occasion with an order update which was much appreciated!), but when it did arrive was very easy to install. Both the heat and AC function work perfectly, and our family is very happy!

Decent Company

I ordered a HVAC system and it arrived in a timely manner and with no apparent issues. I thought the system was defective once installed but it was the installers fault who wired it wrong. My only issue would be the fee (30% I believe) to return a defective item within the 30 day return policy. If it is defective the customer shouldn't have to pay a fee to return an item that is not operating as designed. Other than that this is a good company.

Pretty Easy Install and Works Great!

Installed my own central HP system. It was a bit of work but nothing beyond a person with basic mechanical and electrical skills. It took me a while because I had to remove the existing electric forced air furnace from a pretty tight place. Some custom sheet metal work and a bit of custom electrical too. Worked perfectly when powered up and I actually like the thermostat provided, although I wish it was clearer how to set up a temperature set-back schedule. Pre-charged refrigerant piping was something new and I liked that too. The best thing is that my electric utility forked out $4,000 and that paid for the unit!

Installed and working great

Installed with ceiling cassettes... Quiet and keeping us cool so far !

The "COOLEST" unit!

Sure! Here’s a **funny, pun-filled review** you could post online about a **Mr. Cool mini split** — you can tweak it depending on whether you want it to sound like a casual customer or a witty product review.

---

😎 “Mr. Cool? More Like Mr. Ice-olation Station!”

Check this guy out. Mr. Cool. He doesn’t talk back, he keeps his chill no matter how heated things get, and best of all, he "splits" his time evenly between cooling and heating. Talk about a balanced relationship! Installation was a breeze (literally). I expected drama, sweat, and a few choice but once he moved in, the temperature dropped faster than my motivation to leave the house.
Now my living room is so cool, penguins are sending me roommate requests. My electric bill? It’s giving "light chill, not frostbite."
Whether it’s summer meltdown season or winter’s silent treatment, Mr. Cool always knows how to vent properly. I’ve never had such a fan-tastic relationship before. So yeah, call me biased, but this unit really "blew me away".

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MRCOOL DIY 5th Gen 66 Ft. 1/4" x 3/8" Line Set for DIY 6K, 9K, & 12K Indoor (DIY66-1438-O)

Package Overview

Package Includes:

Shipping & Returns

Customer Reviews

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