If your True refrigeration unit stopped holding temp or started short-cycling, the compressor is the first place to look. True makes solid commercial equipment, but their sealed systems fail in predictable ways, and most of those failures leave clues before the unit dies completely.
Most Common Compressor Problems in True Units
Short-cycling is the most frequent complaint. The compressor kicks on, runs for a minute or two, then shuts off before the box gets cold. This is almost always a refrigerant issue (low charge, leak, or restriction) or a failing compressor that can’t build adequate head pressure. It can also be a bad start relay, which is a cheap fix people often miss.
Not starting at all. You hear a click, maybe a hum, then nothing. That pattern points to the start relay or start capacitor. These are small components that sit on the side of the compressor. They fail with age and heat.
Running constantly but not cooling. The compressor runs, the condenser fan runs, but the box temperature drifts up. This usually means low refrigerant from a leak, a dirty condenser coil choking airflow, or a failing compressor that’s lost compression capacity. A compressor that’s “pumping weak” is on its way out.
Tripping the overload protector. The compressor gets too hot and the thermal overload cuts power to protect it. The unit goes warm, might recover overnight, then fails again. This can repeat for weeks before someone calls for service. Root causes: dirty condenser, low refrigerant, bad head pressure from a failed fan motor, or a compressor that’s mechanically worn.
Hard starting. The compressor struggles to start under load. You hear a prolonged hum before it kicks in, or it doesn’t start at all. Older True units develop this as they age. A tech can fit a hard start kit when the refrigerant charge and everything else checks out.
What a Tech Checks on Arrival
A competent tech walks up to a True unit and does a few things before opening anything.
First, they listen. A compressor that’s rattling, knocking, or making a grinding noise is mechanically compromised. One that hums and trips the overload tells a different story than one that won’t even try to start.
Then they check the condenser coils. On most True reach-in units, the condenser is at the bottom behind a louvered access panel, though the location varies by model line (some Spec Series units have a top-mounted condenser). On walk-in condensing units, it’s wherever the condensing unit is mounted. A condenser packed with grease and dust will cause overheating and high head pressure. This is a maintenance issue that masquerades as a compressor problem constantly.
After that, they pull the start relay and test it with a multimeter. If it rattles or reads open, it gets replaced before anything else. A compressor that looks dead sometimes comes back to life with a new relay.
If those don’t explain it, they connect gauges. Low suction pressure with high superheat points to low refrigerant or a starved coil. A weak compressor with failing valves shows a different pattern: head pressure that’s lower than it should be combined with suction pressure that’s higher than normal, because discharge gas leaks back across the valves. A restriction (plugged filter-drier or capillary tube issue) typically shows low suction with low discharge and high superheat at the outlet. Reading all three together, not just one number, is how a tech tells these apart.
For True units specifically, the evaporator fan motors matter too. True walk-ins and reach-ins use multiple evaporator fans, and if one or more fail, airflow across the evap coil drops, suction pressure drops, and the compressor can eventually trip on overload. It looks like a compressor problem until you check the fans.
What You Can Check Before Calling
Two things are genuinely within reach for an operator.
Clean the condenser coils. This is the single most effective preventive step you can take. On most True reach-in units, the condenser is at the bottom behind a louvered panel. True recommends checking coils frequently in commercial kitchen environments. Quarterly is a minimum; monthly is better if the kitchen is greasy. A clogged condenser causes more compressor failures than any other single factor.
Confirm the fans are spinning. When the compressor is running, the condenser fan should be moving. Same for the evaporator fans inside the cabinet. A stopped fan is visible immediately. Note which one isn’t running, then call a tech.
That’s where the operator checklist ends. Anything beyond that involves electrical diagnosis (relay testing, winding checks, capacitors, control boards) or refrigerant, and both require proper tools and certification. A misstep on refrigerant charge alone can destroy a compressor in hours. Section 608 certification is a federal requirement before anyone can purchase or handle refrigerant, and suppliers are required to verify it.
Time to Call
Call when the unit isn’t holding temperature and you’ve already cleaned the condenser and confirmed the fans are running. You’ve done the easy stuff. What’s left is sealed-system work or component diagnosis, and that needs a licensed refrigeration tech.
Don’t wait if the compressor is tripping overload repeatedly. Running a failing compressor when it might be saveable (bad relay, dirty coils, low charge) turns a repair into a replacement. A diagnostic visit costs a fraction of a compressor swap.
True compressor replacements aren’t cheap. Labor plus the compressor on a reach-in runs several hundred dollars or more depending on unit size; walk-in condensing units run higher. Catching it early, when it’s still a relay or a dirty coil, saves real money.
If your True unit is acting up in the Bay Area, Bay Area Refrigeration Service handles commercial refrigeration on walk-ins, reach-ins, ice machines, and prep tables. Give us a call or contact us at bayarearefrigerationservice.com and we’ll get you on the schedule fast, often same or next day when we can.