BASIC TN1900 Refrigerator Compressor
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BASIC TN1900 Refrigerator Compressor: Technical Specifications and Low Back Pressure Performance Analysis
Comprehensive technical guide on BASIC brand TN1900 refrigeration compressor specifications, maintenance, troubleshooting, and performance comparison with international standards for WordPress SEO optimization.
Understanding the BASIC TN1900 Refrigerator Compressor System
The BASIC TN1900 represents a medium-displacement hermetic reciprocating compressor specifically engineered for low back pressure (LBP) refrigeration applications including domestic refrigerators and freezers. This Syrian-manufactured cooling unit operates on R134a refrigerant with a 220-240V 50/60Hz power supply, delivering approximately 200-250W cooling capacity at standard evaporating temperatures between -30°C and -10°C. With a displacement volume of 7.0 cubic centimeters and an RSIR (Resistance Start Induction Run) motor type, the TN1900 provides reliable performance comparable to international standards including Panasonic QB series compressors used in commercial refrigeration applications. The unit weighs approximately 80 kilograms with an oil charge of 280 cubic centimeters stored capacity, designed for vertical mounting in freezer compartments with static or forced-air cooling configurations.
Refrigerant Specifications and R134a Performance Characteristics
The R134a refrigerant selected for the BASIC TN1900 represents a hydrofluorocarbon (HFC) chemical compound specifically formulated for low to medium back pressure applications in domestic and light commercial cooling systems. Unlike older R12 refrigerants which face global phase-out due to ozone depletion concerns, R134a maintains zero ozone depletion potential while offering superior thermodynamic properties for modern compressor designs. The refrigerant charge of 140 grams specified for the TN1900 system requires precise measurement and handling, as R134a exhibits higher pressure levels compared to eco-friendly alternatives like R600a (isobutane) which charges only 45% of equivalent R134a capacity.
The evaporating temperature range of -30°C to -10°C positions the TN1900 within the LBP classification, requiring compressor motors with high starting torque to overcome initial pressure differential stresses. In contrast, R600a refrigerant systems operate at lower pressures but demonstrate superior energy efficiency with COP improvements of 28.6% to 87.2% over R134a in identical cooling loads. However, R600a flammability characteristics (A3 classification) necessitate specialized safety protocols and reduced charge quantities below 150 grams per unit, limiting adoption in high-capacity applications.
Low Back Pressure (LBP) Classification and System Application Range
Low Back Pressure compressors operate under high compression ratios approximately 10:1 when condensing temperatures reach 54.4°C while evaporating temperatures drop to -23.3°C, creating extreme pressure differentials that demand robust mechanical construction. The BASIC TN1900’s displacement of 7.0 cm³ enables processing of approximately 140-150 cubic centimeters of refrigerant vapor per compression cycle at 50Hz operational frequency, directly influencing cooling capacity and system refrigeration rate.
LBP applications extend across freezer compartments in upright or chest-type units, ice-making machines, food preservation cabinets, and laboratory deep-freezing equipment operating at temperatures below -20°C. The classification contrasts sharply with MBP (Medium Back Pressure) systems used in beverage coolers (-20°C to 0°C evaporation) and HBP (High Back Pressure) units for dehumidifiers and air conditioning (-5°C to +15°C ranges). Selecting appropriate compressor back-pressure designation proves critical because installing HBP compressors in LBP applications causes rapid compressor failure through excessive shaft wear, valve-plate damage, and premature thermal shutdowns.
Technical Specifications: Displacement, Capacity, and Coefficient of Performance
The Panasonic QB77C18GAX0 reference compressor with 7.69 cm³ displacement demonstrates performance metrics directly comparable to the BASIC TN1900’s 7.0 cm³ displacement, both delivering approximately 220-224W cooling capacity at -23.3°C evaporation temperature. The QB77C18GAX0 achieves a COP (Coefficient of Performance) of 1.31, indicating high-efficiency operation with 224 watts cooling output per 172 watts electrical input. In contrast, the BASIC TN1900 exhibits COP values between 1.1-1.3 depending on actual operating conditions, ambient temperature variations, and refrigerant charge accuracy.
Cooling capacity measurements vary significantly across different evaporating temperatures, following thermodynamic principles where lower evaporating temperatures produce proportionally reduced cooling watts despite constant compressor displacement. At -30°C evaporation (typical deep freezer operation), the QB77C18GAX0 delivers approximately 145W, declining from 224W capacity at -23.3°C. This 41% capacity reduction reflects the increased compression ratios and motor workload inherent to ultra-low temperature applications, explaining why larger displacement compressors become necessary for freezer compartments operating below -25°C.
| Temperature Condition | Evaporating Temp | QB77C18GAX0 Capacity (W) | Input Power (W) | Theoretical COP |
|---|---|---|---|---|
| Ultra-Low Freezing | -30°C | 145 W | 111 W | 1.31 |
| Deep Freezer Standard | -25°C | 202 W | 154 W | 1.31 |
| Low Temperature | -23.3°C | 224 W | 172 W | 1.31 |
| Medium Freezer | -20°C | 272 W | 208 W | 1.31 |
| Refrigerator Freezer | -15°C | 354 W | 270 W | 1.31 |
Motor Type Analysis: RSIR vs. CSIR vs. PSC Motor Technologies
The RSIR (Resistance Start Induction Run) motor classification represents the fundamental motor design selected for the BASIC TN1900, employing a secondary starting winding energized exclusively during the initial compression startup phase. This economical motor configuration utilizes higher resistance wire in the auxiliary winding to create the necessary magnetic field phase shift for initial torque development, automatically disengaging once the compressor reaches approximately 75% of rated speed through a centrifugal switch or thermal current relay.
RSIR motors demonstrate inherent efficiency limitations of 8-10% compared to PSC (Permanent Split Capacitor) designs but provide substantial cost savings and simplified electrical components. For LBP applications like the TN1900, RSIR motor selection remains optimal because deep freezer compressors require significant starting torque to overcome pressurized refrigerant columns in the cylinder, necessitating the secondary winding assistance. In contrast, CSIR (Capacitor Start Capacitor Run) motors utilize two capacitors (starting and running) for enhanced efficiency and reduced electrical consumption, better suited to MBP/HBP applications where compressor starting loads remain moderate.
The defrost system integration shown in the BASIC TN1900 wiring schematic incorporates the defrost thermostat (Bi-metal element) in series with defrost heater elements (H1, H2, H3, H4, H5) controlled by the main thermostat and defrost timer circuit. The door switch activates the refrigerator lamp, while the freezer fan motor operates continuously during compressor running cycles, ensuring cold air circulation throughout both freezer and refrigerator compartments.
Wiring Schematic Analysis: Defrost Timer and Thermostat Circuit Integration
The BASIC TN1900 wiring diagram demonstrates the fundamental electrical architecture required for automatic defrost systems in domestic refrigerators, incorporating four distinct operational phases: normal cooling, defrost initiation, defrost heating, and defrost termination. The defrost timer mechanically switches between cooling mode (compressor running, freezer fan operating) and defrost mode (compressor off, defrost heater energized) on approximately every 8-10 hours of compressor runtime, preventing excessive frost accumulation on the evaporator coil assembly.
Temperature sensing through the bi-metal defrost thermostat terminates heating element operation once the evaporator temperature reaches approximately 40°F to 70°F (4°C to 21°C), preventing over-defrosting and unnecessary energy consumption. This safety mechanism proves absolutely critical because extended defrost operation would warm the freezer compartment and potentially spoil stored food items. The defrost thermostat contains a sealed mercury vial that moves within the bimetallic housing as temperature fluctuates, completing or breaking the electrical circuit through mechanical contact points without requiring external electronics.
Common defrost system failures include:
- Defective defrost heater elements (H1-H5) losing continuity or developing internal fractures, preventing ice melting and forcing manual defrost cycles
- Bi-metal thermostat malfunction failing to terminate heating at target temperatures, causing warm refrigerator compartments and food spoilage
- Defrost timer mechanical failure jamming in either heating or cooling mode, eliminating automatic cycle switching
- Thermal fuse rupture triggered by defrost system overheating, permanently disabling both heating and cooling functions
- Water drain blockage preventing defrost water evacuation, causing ice backup into the freezer compartment
Compressor Troubleshooting: Starting Relay, Thermal Protection, and Electrical Diagnostics
The compressor starting relay (current relay or thermal relay) serves as the critical electrical component that removes the auxiliary winding from the circuit after the compressor achieves sufficient rotational speed. A faulty relay allows excessive current flow through the starting capacitor and auxiliary winding indefinitely, causing motor winding insulation breakdown and compressor burnout within minutes of operation. Testing the relay requires disconnecting from the refrigerant system and measuring electrical continuity between the RUN and START terminals; if resistance drops to zero ohms during operation, the relay has failed and requires replacement.
The thermal protection device (OOLP – Overload Protection) in the BASIC TN1900 monitors motor winding temperature and automatically opens the electrical circuit when compressor discharge temperatures exceed safe thresholds (typically 130°C winding temperature limit). This safety mechanism prevents catastrophic motor failure from refrigerant flooding, excessive system pressures, or mechanical jamming conditions. A tripped thermal protector requires 20-30 minutes cooling time before automatic reset occurs, allowing internal temperature stabilization and preventing destructive thermal cycling.
Testing compressor continuity involves:
- Identify three terminals: Common (C), Run (R), and Start (S) through resistance measurements using a multimeter
- Measure C-R resistance (should read 5-30 ohms): lowest resistance typically indicates run winding
- Measure C-S resistance (should read 30-100 ohms): secondary winding shows higher resistance
- Measure R-S resistance (should equal C-R plus C-S): confirms proper winding continuity
- Between-terminal resistance below 1 ohm indicates electrical short circuit requiring compressor replacement
- Infinite resistance on any terminal pair signals open circuit (broken winding) making the compressor non-functional
Cooling Capacity Comparison Across Compressor Displacement Ranges
The BASIC TN1900 with 7.0 cm³ displacement provides approximately 28% greater cooling capacity than typical 1/6 HP compressors featuring 4.6 cm³ displacement, yet delivers comparable power consumption around 180-210 watts. This relationship illustrates the direct proportionality between compressor displacement and refrigeration capacity, where larger swept volumes process greater refrigerant masses per compression cycle, enabling increased heat removal rates.
The Panasonic QB77C18GAX0 reference standard with 7.69 cm³ displacement represents the next larger displacement class, achieving approximately 8% higher capacity than the TN1900 while consuming only 8% additional electrical power, demonstrating superior thermodynamic efficiency inherent to slightly larger displacement designs. However, excessive displacement increases electrical demand exponentially, explaining why oversizing compressors for applications creates energy inefficiency and reduced seasonal COP performance.
Compressor displacement directly affects system design considerations:
- Larger displacement (8-10 cm³): Enhanced cooling capacity for spacious freezer compartments and secondary cooling loop systems
- Medium displacement (5-7 cm³): Optimal for standard domestic refrigerator/freezer combinations with efficient part-load operation
- Small displacement (3-4 cm³): Limited to compact refrigeration units and miniature freezers with restricted storage volumes
Environmental and Energy Efficiency Implications
The R134a refrigerant’s Global Warming Potential (GWP) of 1450 indicates that 1 kilogram of R134a contributes 1450 times more to atmospheric warming than equivalent carbon dioxide masses over a 100-year period. This climate impact concern has driven international regulatory frameworks limiting R134a applications and incentivizing transition toward R290/R600a natural refrigerants with GWP values of 3-4.
The BASIC TN1900’s COP efficiency of 1.1-1.3 watts-cooling per watt-electrical input compares unfavorably to modern R290/R600a systems achieving COP values of 1.4-1.6, translating into 20-30% increased electricity consumption for equivalent cooling capacity. Over the 15-20 year operational lifespan of a typical domestic refrigerator, this efficiency differential costs consumers approximately $400-600 in excess electricity while contributing proportionally greater greenhouse gas emissions.
Maintenance Protocols and Component Replacement Procedures
Preventive maintenance for the BASIC TN1900 refrigerator system encompasses:
Monthly inspections: Visual examination of condenser coil exterior for dust accumulation, verification of freezer seal integrity, and assessment of door hinge functionality
Quarterly cleaning: Gentle brush removal of dust from condenser coil tubes and fan blades using low-pressure air flow to prevent aluminum fin damage; vacuum cleaning of the base pan and drain water catchment area to prevent mold growth and drain blockage
Annual compressor assessment: Listen for abnormal grinding, squealing, or chattering sounds indicating bearing wear or mechanical failure; verify compressor power cord insulation for damage or deterioration; confirm thermal protector intermittent tripping patterns suggesting elevated discharge pressures
Defrost system validation: Monitor evaporator coil frost accumulation across defrost cycles; verify water drainage from defrost collection pan without freezing; test door closure latching ensuring proper seal under negative pressure
Refrigerant charge verification: Request professional technician evaluation if cooling capacity declines gradually or compressor discharge line becomes excessively warm (above 90°C), indicating partial refrigerant leakage
Comparison with International Compressor Standards and European Alternatives
The BASIC TN1900 performance specifications align closely with Panasonic QB77 series models manufactured in Japan and Indonesia, representing the international standard for 7-8 cm³ displacement LBP compressors. Embraco and Tecumseh compressors from Brazilian and North American manufacturers respectively offer equivalent displacement ratings with COP values 3-5% higher due to advanced refrigerant management technology and improved valve plate design.
European refrigeration regulations increasingly mandate minimum COP thresholds of 1.45 for LBP applications, meaning the BASIC TN1900 operating at COP 1.1-1.3 would not meet modern efficiency standards in markets like the European Union, UK, or Switzerland. This regulatory disparity reflects manufacturing cost differentials, with advanced compressors incorporating precision-machined components and optimized refrigerant flow passages commanding premium pricing that makes older designs economically viable in developing regions where cost sensitivity outweighs energy efficiency priorities.





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Excerpt (55 words): “The BASIC TN1900 represents a medium-displacement hermetic reciprocating compressor engineered for low back pressure refrigeration applications. This Syrian-manufactured unit operates on R134a refrigerant with 220-240V 50/60Hz power supply, delivering 200-250W cooling capacity at -30°C to -10°C evaporating temperatures with RSIR motor technology.”
