# When an absorption refrigerator cooling unit drops out under load on the SR-60 corridor An absorption cooling unit is sealed and cannot be recharged. The tells that separate a gas fault from a dead cooling unit, and why the repair splits between $285 LP service and a $4,500 replacement. ## An absorption unit cannot be recharged The first thing an owner usually says on the phone is that the refrigerator needs a recharge. That instinct comes from automotive air conditioning, where a system loses refrigerant slowly and gets topped up. An absorption refrigerator does not work that way. The cooling unit is a sealed steel circuit welded shut at the factory, charged once with ammonia, water, hydrogen and a sodium chromate corrosion inhibitor, and there is no service port anywhere on it. Nobody recharges it, here or anywhere else. That single fact reorganizes the whole diagnosis. Because the circuit cannot be opened, every repair falls on one side of a hard line. Either the problem is in the parts that feed and control the cooling unit, which are all serviceable and mostly inexpensive, or the problem is inside the sealed circuit, in which case the circuit gets replaced as an assembly. There is no middle repair and no additive that changes the outcome. Knowing which side you are on before you spend money is the entire point of this article, because owners routinely authorize a new control board on a coach whose cooling unit is already blocked, and then authorize the cooling unit anyway six weeks later. ## The tells that separate a gas fault from a dead cooling unit Start with the source of heat. If the refrigerator cools acceptably on 120 volt shore power but will not hold temperature on LP, the sealed circuit is fine and the fault is in the gas train: the burner orifice, the flue, the thermocouple or electrode, or the delivery pressure at the regulator. If it fails on both heat sources equally, suspicion moves inside the circuit. Then read the cabinet. A cooling unit that is losing capacity fails from the top down. The freezer keeps holding while the fresh food compartment climbs into the fifties, because the evaporator is still boiling off ammonia at the cold end and no longer carrying enough load to the lower fins. An owner reads that as a thermostat problem. It is usually a capacity problem. Then look behind the vent. Two findings are conclusive and both are visible with a flashlight. A yellow or greenish powder deposit on the boiler tube or on the insulation under it is sodium chromate that came out with escaping ammonia, and it means the charge is gone. A sharp ammonia odor at the upper roof vent means the same thing. Either finding ends the diagnosis; no amount of board or element work brings that unit back. ## What SR-60 grades and a 105 degree afternoon do to percolation An absorption unit has no pump. It moves liquid by gravity and by heat, which is why it must sit close to level to run and why it fails in specific conditions rather than randomly. Two of those conditions are ordinary life in this county. The first is heat rejection. The cycle dumps heat from the condenser fins into the air behind the sidewall, and it needs a moving column of air from the lower vent to the roof cap to do it. On a July afternoon with ambient over 100 degrees and the coach parked with the refrigerator wall facing the sun, the air arriving at those fins is already hot, the condenser cannot dump, and the box quietly loses ten degrees over an afternoon. Owners call that dropping out under load, and they are describing airflow. The second is running off level. Sitting nose down on a Hacienda Heights driveway apron or parked on the crossfall of a lot, the weak ammonia solution pools instead of returning, a section of the boiler runs dry and overheats, and sodium chromate crystallizes into a plug. That plug is permanent. Do it once on a hot day and you have converted a $285 gas train visit into a cooling unit. Long climbs on the SR-60 corridor with the unit running on LP simply add heat to a system that was already marginal. ## Burner service, control board, or a replacement cooling unit The inexpensive path is the gas train. LP gas system service runs $285 to $2,500 at 1 to 10 hours and covers a burner and orifice clean, flue inspection, thermocouple or electrode replacement, a leak test, and verification of delivery pressure at the appliance under load with other appliances running, which is where a tired two stage regulator finally shows itself. A hazmat and disposal line of $45 applies flat whenever LP is part of the job. Still on the affordable side, refrigerator repair runs $400 to $4,500 at 1 to 18 hours and covers the electrical half: the control board, the AC heating element, the eyebrow board and its wiring, the thermistor, the door seals, and adding or replacing the compartment fan that fixes most of the heat rejection complaints described above. A fan kit and a resealed baffle is one of the highest value repairs on the whole rate card. The expensive path is a replacement cooling unit, which sits at the top of that same band at $4,500 and 18 hours. It is heavy, awkward work: the box usually comes out through the interior, cabinet trim comes off, and on some floor plans a cabinet face or a wall panel has to be opened and refinished afterward at $500 to $5,500. Systems work of this size books at 3 business days to 2 weeks once the part is on the shelf. ## Dometic cooling unit supply and the LP certification gate Dometic model and serial numbers matter more here than on almost any other appliance in the coach. A cooling unit is matched to a specific cabinet family, and within that family there are revisions, so the number on the tag inside the fresh food compartment is what gets ordered, not the model on the door. Rebuilt units from specialist suppliers exist alongside new assemblies and the lead times differ, commonly one to two weeks for a current family and considerably longer for a discontinued cabinet. Where the cabinet is genuinely obsolete, the practical alternatives are a whole refrigerator swap in the same opening or a conversion to a 12 volt compressor refrigerator, which is a different job with different electrical load consequences and sits in the electrical bands rather than the appliance band. We price those side by side rather than pretending the sealed unit can be salvaged. The certification detail is worth knowing because it decides who may legally touch what. Any work that opens the LP line requires certified LP handling and a documented pressure test afterward. An ammonia absorption circuit, by contrast, is not covered by EPA 608 refrigerant rules at all, so if anyone tells you your RV refrigerator needs a 608 recovery before it is removed, that is not how these units are regulated. ## When a claim actually pays on a refrigerator Not for capacity loss. A cooling unit that crystallized from running off level, or that lost its charge after fifteen years of thermal cycling, is mechanical wear and every policy excludes it. Filing that claim wastes the deductible conversation and ends in a defensible denial. Claims do pay in two situations, and both are worth documenting carefully. The first is fire, which has a real history with these appliances: a boiler tube failure that scorches the enclosure or damages the sidewall is a sudden event, and the sidewall, cabinetry and roof damage that follows is in scope. The second is collision, where the box moved, racked in its opening, or lost the roof vent stack. Where an appliance is under an active manufacturer recall or campaign, that is a separate channel from the insurance claim and it goes back through the brand rather than the carrier. We will tell you which of the three you are actually in before you file anything, because they cannot be pursued in the same document. ## Three checks to run before you drive it in Do these three things first and the diagnostic gets shorter and cheaper. Run the unit on shore power alone for eight hours with a thermometer in a glass of water on the middle shelf, then repeat on LP alone, and write down both results. Pull the lower vent cover and photograph the boiler tube and the insulation under it, looking hard for yellow powder. Note whether the coach was parked level for both tests, and whether that wall faced the sun. Bring the photographs and the two temperature logs with you. All appliance work happens in the shop at OCRV Center, which is 18.4 miles from Hacienda Heights and 24 to 38 minutes away by SR-60 west to Fullerton Road, or by SR-60 to SR-57 south and SR-91 east. Call (949) 799-3387 with the model and serial from inside the compartment and we will check cooling unit availability before you commit to a date. The RV systems estimate is $150 and is credited against an authorized repair; an in depth diagnostic is one hour at $285 on the same terms. --- Source: https://ocrv.club/blog/absorption-refrigerator-cooling-unit-drops-out-under-load-on-the-sr-60-corridor OCRV Center, 23281 La Palma Ave, Yorba Linda, CA 92887 Phone (949) 799-3387. Email info@ocrvcenter.com. Serving Hacienda Heights and the surrounding area. 18.4 miles, 24 to 38 minutes via SR-60 west to Fullerton Rd, then south to La Palma Ave. In shop work only. All estimates are priced and credited against an authorized repair.