If you maintain an ammonia refrigeration system, there’s one situation that can spoil your day in a hurry: a too-hot-running compressor. It’s more than a warning light or a temperature reading. Too much heat can result in actual damage, costly repairs, or even complete system shutdown. But don’t go ballistic or summon the troops just yet; here’s what to inspect, what to do, and how to keep your system secure.
First: Understand Why It Matters
Ammonia compressors are built to work within a specific temperature range. When that threshold gets crossed, things can spiral. Oil breaks down, components wear faster, and in severe cases, the compressor can seize. If you’re noticing unusual heat levels, don’t ignore it or hope it resolves itself. Heat is always a signal.
Step 1: Verify the Readings
Before tearing the system apart, make sure the readings are accurate. Faulty sensors or gauges can give false alarms. Cross-check the temperature data with a handheld thermometer or infrared gun. Also, compare with system logs to see if this is a trend or a sudden spike.
Step 2: Check Oil Levels and Quality
Low oil or dirty oil is one of the most prevalent causes of overheating. The compressor is dependent on oil for lubrication and thermal transfer. If the oil level is low, an emergency top-off may temporarily repair it, but you still must determine the cause of the loss. If the oil appears dark, burnt, or has an unpleasant odor, it’s time to change the oil and potentially the filter.
Step 3: Inspect Suction Pressure and Superheat
Too low suction pressure or high superheat can starve the compressor of enough refrigerant, making it work harder and heat up. Check your expansion valves and evaporator performance. Are you feeding the compressor properly? Also look at any restrictions in the suction line that might be choking flow.
Step 4: Examine the Cooling System
Compressors often rely on auxiliary cooling: either water-cooled jackets or air-cooled systems. If that system fails, temperatures will rise fast. Check for:
- Water flow issues (blocked lines, low pressure)
- Fan problems (not spinning, broken blades, electrical issues)
- Dirty heat exchangers or condensers
- Scale buildup in water-cooled systems
Cleaning and restoring proper flow can make a huge difference.
Step 5: Evaluate Motor Load and Amperage
Overloading the motor can cause internal heat buildup. Compare your motor amperage to its nameplate full-load amps (FLA). If you’re exceeding it, that could point to mechanical drag inside the compressor, improper refrigerant charge, or even a misbehaving control valve.
Step 6: Look for Mechanical Wear
Sometimes, the issue is inside. Worn bearings, misaligned shafts, or damaged valves can cause extra friction and lead to overheating. Listen for unusual sounds—grinding, knocking, or squealing. If something sounds off, shut it down and get it inspected.
Step 7: Review System Operation
Has anything changed recently? A new operator, updated control logic, or a different production load can throw off a previously stable system. Review recent changes and make sure setpoints, interlocks, and sequencing logic are working as intended.
Step 8: Don’t Ignore Insulation and Ambient Heat
Is your compressor exposed to high ambient temperatures? Poor ventilation or a failed HVAC system in the compressor room can cause a heat trap. Likewise, damaged insulation on suction lines can result in more heat being transferred into the compressor.
When to Call for Help
If you’ve gone through these steps and the compressor is still running too hot, it’s time to get a technician involved. Chronic overheating can point to internal damage or systemic issues that require deeper diagnostics.
Prevention Tips
- Routine maintenance: Don’t wait for alarms to tell you something’s wrong. Keep your oil clean, filters fresh, and sensors calibrated.
- Log everything: Small trends become big problems. Tracking compressor temps over time gives you an early warning system.
- Keep it clean: Dirty condensers and clogged filters stress the entire system.
- Train your team: Make sure everyone who touches the system knows the signs of trouble and what to do.
Final Thought
An overheated ammonia compressor is more than an inconvenience; it’s a warning. Take it as such. A little attention and action may be enough to avert catastrophic damage, save significant costs, and keep a system running well. Learn the what, where, and when of detecting. Stay sharp, stay cool – literally.