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Independent service company · est. St. Augustine

Old City Cold Storage Co.

Sub-Zero refrigeration, wine storage and ice machines — St. Augustine and St. Johns County

+1 (904) 604-7755 Monday – Friday, 8:00 am – 6:00 pm

built-in refrigeration

Sealed systems, compressors and refrigerant faults

Refrigerant faults are the expensive end of the trade, which is exactly why they should be measured and proved before anybody quotes for them.

The machine compartment of a built-in with the grille off, condenser and fan exposed above a spread of hand tools
Grille off: condenser, fan, line set

What owners describe

  • The cabinet cools a little but never reaches its setting
  • The compressor starts, labours and shuts down within a minute
  • One half of a dual system is warm and the other is normal
  • There is frost on part of the evaporator and none on the rest
  • The unit runs continuously and the grille is hot

The refrigerant circuit is the part of the appliance an owner never sees: compressor, condenser, metering device, evaporator, and the tubing that joins them into a closed loop. When it is right, it is the most reliable thing in the kitchen. When it is wrong, it is the most expensive, and that is precisely why it should be the last conclusion reached rather than the first.

A surprising number of appliances we are asked to look at for “a bad compressor” have nothing wrong with the compressor at all.

What gets blamed and what is usually true

The three faults that most often masquerade as a dead sealed system are a blocked condenser, a stalled condenser fan, and a control fault that has left a component unpowered. All three produce the same headline complaint — the cabinet will not get cold — and all three are cheaper to correct by an order of magnitude.

That is why every visit begins with measurement rather than replacement. Run time across a full cycle. Air temperature in and out of the condenser. Frost pattern across the evaporator. The frost pattern in particular is worth its weight: an evaporator that ices for the first third of its length and stays bare after it is telling you about a restriction or a shortage of charge, in a way that no amount of listening to the compressor will.

When it genuinely is the sealed system

There are three broad cases.

A leak. Refrigerant does not get used up. If there is less of it than there was, it went somewhere, and finding where matters more than adding more. A system topped up without the leak being found is a repair with an expiry date on it, and we will not sell one.

A restriction. Moisture or debris in the circuit narrows the metering point, the evaporator starves, and the cabinet cools partially. This is the fault that most reliably produces the half-frosted evaporator described above.

A compressor that will not start against pressure. It hums, it draws current, it trips its overload, it tries again a few minutes later. Sometimes this is the compressor. Often enough it is the start component feeding it, and that distinction is a large difference on an invoice.

Two systems means two answers

Dual refrigeration — a separate sealed system for the fresh food compartment and another for the freezer — changes the arithmetic of every one of these diagnoses. A cabinet with one system down is not half broken; it is one intact machine and one that needs work. It also removes the most common false conclusion, since a fault affecting only one compartment cannot be a supply problem, a door problem or a room problem. Those would affect both.

The credential this work requires

Sealed-system work involves recovering and handling refrigerant, which is regulated. It is carried out by EPA Section 608 certified technicians. That is the only credential we state anywhere on this site, we hold it, and we hold no appointment from the manufacturer of the appliances we service.

Storms, boards and the fault that looks like refrigeration

St. Johns County sees roughly sixty-eight thunderstorm days in a year. A surge that damages one output on a control board can leave a condenser fan idle while every other function of the appliance behaves normally. The cabinet warms, the compressor runs continuously, the grille gets hot, and the whole presentation is that of a failing sealed system. It is not. It is an electrical fault with a thermal signature, and the measurements above separate the two in about twenty minutes.

Booking

Flat $129 diagnostic, credited toward the repair on approval. Written estimate before any part is ordered. Genuine OEM parts. 90 days on labour and 365 days on parts. Weekdays 8:00 am to 6:00 pm, Saturday 9:00 am to 4:00 pm. Sub-Zero refrigeration only.

After a built-in refrigeration visit

4.8 out of 5, across 22 customer reviews. Each entry below is one visit, described by the person whose kitchen it was.

  • The compressor was running hot and cutting out. He tested the sealed system properly instead of swapping parts, found a partial blockage just after the condenser and cleared it with a new drier.

    Piers G.2026-01-20

  • Somebody else had already quoted us for a replacement cabinet. He put gauges on it, found the charge low from a pinhole at the drier joint, repaired the joint and recharged it. Still holding.

    Orla C.2026-02-03

  • Our freezer sat at ten degrees and would go no lower. He identified a leak at the evaporator return bend, brazed it, pulled a deep vacuum and recharged by weight. It reaches setpoint again now.

    Rhea J.2026-01-06

All 22 of them, in full

Booking this work

$129 flat diagnostic, credited against the repair. A written estimate is presented before any part is ordered or any repair begins. 90 days on labour, 365 days on parts, on every completed repair.

Call +1 (904) 604-7755 Book a visit

Sub-Zero refrigeration only. We do not accept work on other makes.

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