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HVAC and Plumbing Distributor
Jonathon Pullen

Jonathon Pullen

Technical Services Manager
Gulf Coast Distrtict

Because I was Inverted

For this article, I will explain how to replace the main control board on a 38MARB ductless outdoor unit. The boards are inverted or upside down in most ductless outdoor units. 

The 38MARB board has a heat sink under the board that you cannot see with a refrigerant loop running through the heat sink. At first glance, it looks easy to replace, and it is; however, if you do not know about the hidden screws you could damage the refrigerant loop when trying to remove the board. 

Start by removing power to the unit and confirming with a meter. Remove the top cover and the fan side cover exposing the board, fan, and compressor section. 

 

Then remove the wires from the board (this will help when it is time to flip the board over). Next, find the pigtail for the compressor harness and disconnect.

Next, locate the wiring diagram on the board. Once located, take your finger and move it around the board feeling for round holes under the diagram. There are four screws holding the heat sink to the board and three are under the wiring diagram. It is best to insert a #2 Philips head screwdriver through the thin wiring diagram and remove the screws.

Once all four screws are removed, locate the small plastic clips on the front and back of the board and gently release with a flathead.

Simply lift straight up off the heat sink and lay it to the side where the copper and electrical are located. Finish removing the remaining wires and start the new board installation. Remember to add new heat sink paste to the heat sink. If this is not completed the new board may not last long.

Install the new board, assemble the unit, restore power, and check for normal operation.

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Alabama Locations

Anniston (256) 241-3026 105 E D St, Anniston, AL 36201
Auburn (334) 734-8011 2295 1st Ave, Opelika, AL 36801
Birmingham (205) 250-7714 516 31st St N, Birmingham, AL 35203
Dothan (334) 836-1035 205 Wedgewood Dr, Dothan, AL 36303
Gulf Shores (251) 968-2660 820 Commerce Dr, Gulf Shores, AL 36542
Huntsville (256) 859-2691 391 Nick Fitcheard Rd NW, Huntsville, AL 35806
Loxley (251) 964-2707 30020 Co Rd 49, Loxley, AL 36551
Mobile (251) 476-2220 5522 W Commerce Blvd West, Mobile, AL 36619
Montgomery (334) 262-4855 861 Plantation Way, Montgomery, AL 36117
Muscle Shoals (256) 383-6904 107 Commerce St, Muscle Shoals, AL 35661

Georgia Locations

Albany(229) 432-5254205 Baldwin Dr, Albany, GA 31707
Athens(706) 548-2563105 Whitetail Way, Bogart, GA 30622
Atlanta(404) 875-77551290 Tacoma Dr NW, Atlanta, GA 30318
Augusta(706) 651-19503618 Wrightsboro Rd, Augusta, GA 30909
Brunswick(912) 265-5193275 Rose Dr, Brunswick, GA 31520
Columbus(706) 322-38706201 W Hamilton Park Rd, Columbus, GA 31909
Conyers(770) 918-9132335 Gees Mill Business Pkwy NE, Conyers, GA 30013
Forest Park(404) 361-24745158-C Kennedy Rd, Forest Park, GA 30297
Gainesville(770) 297-93352472 Hilton Dr, Gainesville, GA 30501
Lawrenceville(678) 442-10602111 Cedars Rd SE, Lawrenceville, GA 30043
Lithia Springs(770) 948-3451320 Thornton Rd #106, Lithia Springs, GA 30122
Macon(478) 474-85445527 Thomaston Rd, Macon, GA 31220
Marietta(770) 426-05511060 Triad Ct, Marietta, GA 30062
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Peachtree Corners(770) 239-21006675 Jones Mill Ct, Peachtree Corners, GA 30092
Savannah(912) 232-1228103 Central Jct Blvd, Savannah, GA 31405
Statesboro(912) 764-8841126 W Parrish St, Statesboro, GA 30458
Valdosta(229) 245-8200363 Connell Rd, Valdosta, GA 31602
Warner Robins(478) 953-3727110 Byrd Way, Warner Robins, GA 31088

South Carolina Locations

Hilton Head(843) 689-34043715, 21 Hunter Rd, Hilton Head Island, SC 29926

Florida Locations

Fort Walton Beach(850) 244-201776 Beal Pkwy SW, Fort Walton Beach, FL 32548
Panama City(850) 913-05853012 Lisenby Ave, Panama City, FL 32405
Pensacola(850) 438-10054405 N. Palafox Street, Pensacola FL 32505

Mississippi Locations

Hattiesburg(601) 579-96701851 Lincoln Rd, Hattiesburg, MS 39402
Ocean Springs(228) 497-5090Sunplex Industrial Park, 5717 Suntec Drive, Ocean Springs, MS 39564

Commercial Sales

Norcross – North Georgia Hub
(800) 282-4911

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(205) 250-7714

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(800) 342-9250

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(800) 239-7419

Savannah – Southeast Hub
(800) 822-7617

Commercial Parts

[email protected]
(844) 99-CHILL

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Paynewww.payne.comResidential Heating & A/C Products
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Renew Airewww.renewaire.comFixed-Plate ERVs
Totalinewww.totaline.comCompressors, Parts, and Supplies
United CoolAirwww.unitedcoolair.comModular All-Indoor HVAC Systems
 Warren Technologywww.warrenhvac.comElectric Heaters
 Wilo Pumpswww.wilo-usa.comPump Systems for HVAC and Water Supply and Sewage