When winter arrives, frost on the outdoor evaporator is one of the most common phenomena seen in an air source heat pump.
A common question from homeowners, distributors and even new installers is:
“There is frost or ice on the outdoor heat exchanger. Is my heat pump faulty?”
The answer is:
Not necessarily.
Under low outdoor temperatures and humid conditions, evaporator frosting is a normal part of air source heat pump operation. A properly designed heat pump should periodically enter a defrost cycle, melt the frost and then return to normal heating operation.
The real problem begins when:
These conditions can significantly reduce heating capacity, COP and system reliability.
This guide explains how evaporator frosting occurs, how normal frosting differs from abnormal frosting, and how installers can systematically diagnose common defrost problems.
During heating operation, an air source heat pump absorbs heat from outdoor air.
The outdoor heat exchanger therefore works as an evaporator.
Refrigerant inside the evaporator absorbs heat from the surrounding air, causing the surface temperature of the coil to fall below the outdoor air temperature.
Under cold and humid conditions, the coil surface may fall below both:
Moisture in the outdoor air first condenses on the coil and then freezes.
The basic process is:
Cold outdoor air + moisture
↓
Evaporator surface temperature below freezing
↓
Water vapor condenses on the coil
↓
Condensate freezes
↓
Frost forms on the evaporator
Therefore:
Frost on an air source heat pump evaporator during winter heating is not automatically a fault.
The key question is whether the heat pump can detect the frost and remove it effectively.
A thin layer of frost may initially have limited impact.
As the frost becomes thicker, however, it begins to act as an insulating layer between the outdoor air and the evaporator.
At the same time, frost blocks the airflow passages between the fins.
This causes:
Frost accumulation
↓
Reduced airflow
↓
Lower heat transfer efficiency
↓
Lower evaporation temperature and pressure
↓
Reduced heating capacity
↓
More frosting
This can become a negative cycle.
If the problem continues, the evaporator may eventually become covered with thick ice.
Possible consequences include:
This is why reliable defrost control is critical for cold-climate heat pump operation.
Most air source heat pumps use reverse-cycle defrosting.
During normal heating:
Outdoor coil = Evaporator
Indoor/water-side heat exchanger = Condenser
During defrosting, the four-way reversing valve changes the refrigerant flow direction.
The outdoor coil temporarily becomes the condenser.
Hot refrigerant enters the outdoor coil and melts the accumulated frost.
The process can be simplified as:
Heating operation
↓
Controller detects defrost conditions
↓
Four-way valve changes refrigerant direction
↓
Hot refrigerant enters outdoor coil
↓
Frost melts
↓
Defrost termination condition is reached
↓
Four-way valve switches back
↓
Normal heating resumes
For this process to work correctly, several components must operate together:
A fault in any of these areas can produce abnormal frosting.
Before replacing any component, check whether the controller settings are reasonable.
Important parameters may include:
The exact settings vary by manufacturer and model.
As a general reference, some systems may use settings around:
These values should not be treated as universal settings.
Always follow the manufacturer's control logic and technical documentation for the specific heat pump model.
Incorrect defrost parameters can make a mechanically healthy heat pump behave abnormally.
Based on field service experience, abnormal evaporator frosting can generally be divided into eight common situations.
One common winter problem is heavy ice accumulation around the bottom of the outdoor heat exchanger.
In many cases, the refrigeration system itself is working normally.
The real problem is:
Defrost water cannot drain away properly.
During defrosting, a significant amount of melted water flows from the evaporator into the base pan.
If:
water remains inside the outdoor unit and freezes again.
Repeated cycles can gradually create a thick block of ice.
Check:
Remove dirt and ensure that defrost water can drain freely.
Where appropriate, warm water can be used to melt accumulated ice.
Do not use screwdrivers, metal bars or other hard objects to remove ice from the evaporator.
The copper tubes and aluminum fins can easily be damaged.
A punctured refrigerant tube can turn a simple defrost problem into a major refrigeration repair.
This is an important diagnostic pattern.
If the evaporator becomes evenly covered with frost but the heat pump does not enter a successful defrost cycle, two areas should be checked first:
The controller depends on the defrost sensor to determine the evaporator temperature.
If the sensor gives an incorrect reading, the controller may not know that defrosting is required.
A practical field test is to compare the displayed defrost temperature with the actual coil condition.
Depending on the manufacturer's diagnostic procedure, technicians may also position the defrost sensor in contact with frost/ice and observe the temperature response.
If the evaporator is heavily frosted but the sensor still indicates an obviously high temperature, the sensor or its circuit may be faulty.
Possible causes include:
If confirmed faulty, replace the sensor.
If the compressor operates normally and the controller initiates defrost, but hot refrigerant does not flow into the outdoor coil, check the four-way reversing valve.
Possible failures include:
When the valve receives a switching command, there should normally be evidence that the solenoid is operating.
If the coil is electrically defective, the valve may not change position.
The solenoid coil may operate correctly, but the internal valve body may remain stuck.
In this case:
The four-way valve may need replacement.
Because this repair involves the refrigeration circuit, it should be performed by qualified HVAC/refrigeration technicians.
Another common condition is:
The heat pump enters defrost mode and melts some frost, but significant frost remains after defrosting ends.
You may see:
Two common causes should be considered.
If the controller ends defrost too early, the evaporator may not receive enough heat to melt all accumulated frost.
The unit then switches back to heating with frost still present.
The remaining frost becomes the foundation for the next frosting cycle.
Over time, ice accumulation can become increasingly severe.
The defrost termination setting should be checked and adjusted according to the manufacturer's specification.
Even if the temperature setting is reasonable, the maximum allowed defrost time may be too short for actual weather conditions.
This can occur during:
If the defrost cycle ends before the evaporator is clean, the duration may require adjustment within the manufacturer's permitted range.
Sensor location is extremely important.
If the sensor is installed in an area that warms faster than the most heavily frosted section, the controller may think defrosting is complete while another part of the evaporator is still covered in ice.
A better sensor location is generally a point representative of the coldest or most persistent frosting area, according to the manufacturer's design.
Incorrect sensor positioning can cause premature defrost termination even when the sensor itself is functioning correctly.
Frequent defrosting is another common customer complaint.
A customer may report:
“The heat pump keeps entering defrost mode every few minutes.”
First, determine whether the frequent frosting is caused by environmental conditions or by a system fault.
If the defrost temperature reading is normal and indicates a genuinely cold evaporator, inspect the airflow around the outdoor unit.
Check for:
Poor airflow causes the evaporator temperature to fall and accelerates frosting.
Dust and debris on the evaporator fins reduce airflow and heat transfer.
This can cause:
The evaporator should be cleaned carefully without damaging the fins.
If the system exits defrost before the coil is fully clean, residual frost remains.
The remaining frost causes the next frosting cycle to occur sooner.
Therefore, repeated short defrost cycles may sometimes be caused by an incomplete previous defrost.
If the heat pump repeatedly develops frost and the refrigeration pressure is abnormally low, refrigerant shortage should be considered.
A basic diagnostic process may include:
Low suction pressure can be associated with:
Do not diagnose refrigerant shortage based on frost appearance alone.
Operating pressures, temperatures, superheat/subcooling where applicable, ambient conditions and manufacturer data should all be considered.
If leakage is suspected, locate and repair the leak before recharging refrigerant.
The outdoor fan is essential for transferring heat from ambient air to the refrigerant.
If airflow decreases, the evaporator becomes colder and frosting accelerates.
Possible causes include:
Symptoms may include:
Always verify that the fan is operating correctly and that the airflow path is unobstructed.
Uneven frosting is an important diagnostic clue.
For example:
This often indicates uneven refrigerant distribution.
A common cause is restriction in one refrigerant circuit or capillary tube.
Possible reasons include:
As a result, refrigerant flow through the evaporator becomes uneven.
A qualified technician should inspect the refrigerant distribution circuit.
Depending on the design, troubleshooting may involve:
This work should only be performed by qualified refrigeration technicians.
If the heat pump enters high-pressure protection specifically during the defrost cycle, check the defrost termination settings.
One possible cause is:
The defrost termination temperature is set too high.
The unit may remain in reverse-cycle defrost longer than necessary, causing condensing pressure to rise excessively.
The termination temperature should be checked against the manufacturer's recommended setting.
For some systems, a value around 10°C may be used, but the correct parameter depends on the model.
Do not apply one universal value to all heat pumps.
Low-pressure protection during defrost may be related to the refrigerant expansion device.
One possible cause is an expansion valve that is:
Depending on the system design, troubleshooting may require:
Because expansion valve adjustment differs significantly between heat pump designs, technicians should always follow the specific manufacturer's service documentation.
The opposite problem can also occur.
The evaporator is relatively clean, but the heat pump still enters defrost mode.
This is known as false or unnecessary defrosting.
Possible causes include:
If the controller falsely interprets the evaporator as being frosted, it may initiate unnecessary defrost cycles.
This reduces heating efficiency because every unnecessary defrost interrupts normal heating.
Check:
If the sensor is defective, replace it.
If the parameter is incorrect, adjust it according to the manufacturer's specification.
This is one of the most important questions for heat pump users.
Usually:
Warning signs include:
The presence of frost alone does not determine whether there is a fault.
Frost pattern, defrost behavior and system performance must be evaluated together.
| Symptom | Possible Cause | Recommended Check |
|---|---|---|
| Ice mainly at evaporator bottom | Poor drainage | Check base pan and drain holes |
| Entire coil frosted, no defrost | Sensor or four-way valve | Check sensor reading and reversing operation |
| Defrost incomplete | Short defrost / low termination setting | Check defrost parameters |
| One side remains frosted | Sensor position or refrigerant distribution | Check sensor location and circuit flow |
| Frequent frosting | Poor airflow | Check fan, coil and installation clearance |
| Frequent frosting + low pressure | Refrigerant shortage/restriction | Check refrigeration system |
| Partial/uneven frosting | Refrigerant distribution problem | Check capillary/refrigerant circuit |
| High pressure during defrost | Defrost termination too high or other system issue | Check settings and operating pressure |
| Low pressure during defrost | Expansion device/refrigerant flow issue | Inspect expansion valve and refrigerant circuit |
| Defrost without visible frost | Sensor/parameter problem | Check initiation temperature and sensor |
Instead of immediately replacing components, use a systematic sequence.
Step 1 — Observe the frost pattern
Is the frost:
Step 2 — Check whether the unit enters defrost
If not, inspect:
Step 3 — Observe the defrost result
Does the evaporator become substantially clean?
If not, check:
Step 4 — Check outdoor airflow
Inspect:
Step 5 — Check the refrigeration circuit
If pressures or frost distribution are abnormal, investigate:
This approach helps technicians move from the simplest external causes toward more complex refrigeration faults.
Many winter frosting problems can be prevented before they become service calls.
Check:
Ensure:
Regularly inspect:
Early detection can prevent a minor frosting issue from becoming a complete evaporator freeze-up.
Yes. Frost can be completely normal during heating operation when outdoor air is cold and humid. The important factor is whether the unit can automatically and effectively defrost.
Possible causes include poor drainage, failed defrost control, incorrect sensor readings, four-way valve problems, insufficient airflow, low refrigerant charge or refrigerant circuit restrictions.
Frequent defrosting may be caused by high humidity, poor airflow, dirty evaporator fins, incorrect defrost settings, sensor problems, refrigerant shortage or incomplete previous defrost cycles.
Uneven frost can indicate uneven refrigerant distribution or a restriction in one of the refrigerant circuits. The refrigeration system should be inspected by a qualified technician.
The defrost initiation temperature may be set incorrectly, or the defrost temperature sensor may be faulty or incorrectly positioned.
Yes. Insufficient refrigerant can lower evaporation pressure and temperature and may contribute to abnormal frosting. However, frost alone is not enough to diagnose low refrigerant charge.
If manual de-icing is necessary, avoid sharp or hard objects that can damage fins or puncture refrigerant tubes. The underlying cause of severe icing should also be identified rather than repeatedly removing the ice.
Evaporator frosting itself is not necessarily a heat pump fault.
During winter heating operation, frosting is a natural result of extracting heat from cold and humid outdoor air.
What determines whether the system is operating correctly is its ability to:
Detect frost → Initiate defrost → Reverse the refrigerant cycle → Melt the frost → Drain the water → Return to efficient heating
When abnormal frosting occurs, technicians should avoid immediately blaming the refrigerant charge or replacing the controller.
Instead, look at the frost pattern.
Different patterns provide different diagnostic clues:
Bottom icing → Check drainage
Entire coil frosted with no defrost → Check sensor and four-way valve
Incomplete defrost → Check defrost duration, termination temperature and sensor position
Frequent frosting → Check airflow, refrigerant condition and fan performance
Uneven frosting → Check refrigerant distribution and restrictions
False defrost → Check sensor and defrost initiation parameters
Good troubleshooting is not simply about removing frost.
It is about understanding why the frost was not removed correctly in the first place.
When winter arrives, frost on the outdoor evaporator is one of the most common phenomena seen in an air source heat pump.
A common question from homeowners, distributors and even new installers is:
“There is frost or ice on the outdoor heat exchanger. Is my heat pump faulty?”
The answer is:
Not necessarily.
Under low outdoor temperatures and humid conditions, evaporator frosting is a normal part of air source heat pump operation. A properly designed heat pump should periodically enter a defrost cycle, melt the frost and then return to normal heating operation.
The real problem begins when:
These conditions can significantly reduce heating capacity, COP and system reliability.
This guide explains how evaporator frosting occurs, how normal frosting differs from abnormal frosting, and how installers can systematically diagnose common defrost problems.
During heating operation, an air source heat pump absorbs heat from outdoor air.
The outdoor heat exchanger therefore works as an evaporator.
Refrigerant inside the evaporator absorbs heat from the surrounding air, causing the surface temperature of the coil to fall below the outdoor air temperature.
Under cold and humid conditions, the coil surface may fall below both:
Moisture in the outdoor air first condenses on the coil and then freezes.
The basic process is:
Cold outdoor air + moisture
↓
Evaporator surface temperature below freezing
↓
Water vapor condenses on the coil
↓
Condensate freezes
↓
Frost forms on the evaporator
Therefore:
Frost on an air source heat pump evaporator during winter heating is not automatically a fault.
The key question is whether the heat pump can detect the frost and remove it effectively.
A thin layer of frost may initially have limited impact.
As the frost becomes thicker, however, it begins to act as an insulating layer between the outdoor air and the evaporator.
At the same time, frost blocks the airflow passages between the fins.
This causes:
Frost accumulation
↓
Reduced airflow
↓
Lower heat transfer efficiency
↓
Lower evaporation temperature and pressure
↓
Reduced heating capacity
↓
More frosting
This can become a negative cycle.
If the problem continues, the evaporator may eventually become covered with thick ice.
Possible consequences include:
This is why reliable defrost control is critical for cold-climate heat pump operation.
Most air source heat pumps use reverse-cycle defrosting.
During normal heating:
Outdoor coil = Evaporator
Indoor/water-side heat exchanger = Condenser
During defrosting, the four-way reversing valve changes the refrigerant flow direction.
The outdoor coil temporarily becomes the condenser.
Hot refrigerant enters the outdoor coil and melts the accumulated frost.
The process can be simplified as:
Heating operation
↓
Controller detects defrost conditions
↓
Four-way valve changes refrigerant direction
↓
Hot refrigerant enters outdoor coil
↓
Frost melts
↓
Defrost termination condition is reached
↓
Four-way valve switches back
↓
Normal heating resumes
For this process to work correctly, several components must operate together:
A fault in any of these areas can produce abnormal frosting.
Before replacing any component, check whether the controller settings are reasonable.
Important parameters may include:
The exact settings vary by manufacturer and model.
As a general reference, some systems may use settings around:
These values should not be treated as universal settings.
Always follow the manufacturer's control logic and technical documentation for the specific heat pump model.
Incorrect defrost parameters can make a mechanically healthy heat pump behave abnormally.
Based on field service experience, abnormal evaporator frosting can generally be divided into eight common situations.
One common winter problem is heavy ice accumulation around the bottom of the outdoor heat exchanger.
In many cases, the refrigeration system itself is working normally.
The real problem is:
Defrost water cannot drain away properly.
During defrosting, a significant amount of melted water flows from the evaporator into the base pan.
If:
water remains inside the outdoor unit and freezes again.
Repeated cycles can gradually create a thick block of ice.
Check:
Remove dirt and ensure that defrost water can drain freely.
Where appropriate, warm water can be used to melt accumulated ice.
Do not use screwdrivers, metal bars or other hard objects to remove ice from the evaporator.
The copper tubes and aluminum fins can easily be damaged.
A punctured refrigerant tube can turn a simple defrost problem into a major refrigeration repair.
This is an important diagnostic pattern.
If the evaporator becomes evenly covered with frost but the heat pump does not enter a successful defrost cycle, two areas should be checked first:
The controller depends on the defrost sensor to determine the evaporator temperature.
If the sensor gives an incorrect reading, the controller may not know that defrosting is required.
A practical field test is to compare the displayed defrost temperature with the actual coil condition.
Depending on the manufacturer's diagnostic procedure, technicians may also position the defrost sensor in contact with frost/ice and observe the temperature response.
If the evaporator is heavily frosted but the sensor still indicates an obviously high temperature, the sensor or its circuit may be faulty.
Possible causes include:
If confirmed faulty, replace the sensor.
If the compressor operates normally and the controller initiates defrost, but hot refrigerant does not flow into the outdoor coil, check the four-way reversing valve.
Possible failures include:
When the valve receives a switching command, there should normally be evidence that the solenoid is operating.
If the coil is electrically defective, the valve may not change position.
The solenoid coil may operate correctly, but the internal valve body may remain stuck.
In this case:
The four-way valve may need replacement.
Because this repair involves the refrigeration circuit, it should be performed by qualified HVAC/refrigeration technicians.
Another common condition is:
The heat pump enters defrost mode and melts some frost, but significant frost remains after defrosting ends.
You may see:
Two common causes should be considered.
If the controller ends defrost too early, the evaporator may not receive enough heat to melt all accumulated frost.
The unit then switches back to heating with frost still present.
The remaining frost becomes the foundation for the next frosting cycle.
Over time, ice accumulation can become increasingly severe.
The defrost termination setting should be checked and adjusted according to the manufacturer's specification.
Even if the temperature setting is reasonable, the maximum allowed defrost time may be too short for actual weather conditions.
This can occur during:
If the defrost cycle ends before the evaporator is clean, the duration may require adjustment within the manufacturer's permitted range.
Sensor location is extremely important.
If the sensor is installed in an area that warms faster than the most heavily frosted section, the controller may think defrosting is complete while another part of the evaporator is still covered in ice.
A better sensor location is generally a point representative of the coldest or most persistent frosting area, according to the manufacturer's design.
Incorrect sensor positioning can cause premature defrost termination even when the sensor itself is functioning correctly.
Frequent defrosting is another common customer complaint.
A customer may report:
“The heat pump keeps entering defrost mode every few minutes.”
First, determine whether the frequent frosting is caused by environmental conditions or by a system fault.
If the defrost temperature reading is normal and indicates a genuinely cold evaporator, inspect the airflow around the outdoor unit.
Check for:
Poor airflow causes the evaporator temperature to fall and accelerates frosting.
Dust and debris on the evaporator fins reduce airflow and heat transfer.
This can cause:
The evaporator should be cleaned carefully without damaging the fins.
If the system exits defrost before the coil is fully clean, residual frost remains.
The remaining frost causes the next frosting cycle to occur sooner.
Therefore, repeated short defrost cycles may sometimes be caused by an incomplete previous defrost.
If the heat pump repeatedly develops frost and the refrigeration pressure is abnormally low, refrigerant shortage should be considered.
A basic diagnostic process may include:
Low suction pressure can be associated with:
Do not diagnose refrigerant shortage based on frost appearance alone.
Operating pressures, temperatures, superheat/subcooling where applicable, ambient conditions and manufacturer data should all be considered.
If leakage is suspected, locate and repair the leak before recharging refrigerant.
The outdoor fan is essential for transferring heat from ambient air to the refrigerant.
If airflow decreases, the evaporator becomes colder and frosting accelerates.
Possible causes include:
Symptoms may include:
Always verify that the fan is operating correctly and that the airflow path is unobstructed.
Uneven frosting is an important diagnostic clue.
For example:
This often indicates uneven refrigerant distribution.
A common cause is restriction in one refrigerant circuit or capillary tube.
Possible reasons include:
As a result, refrigerant flow through the evaporator becomes uneven.
A qualified technician should inspect the refrigerant distribution circuit.
Depending on the design, troubleshooting may involve:
This work should only be performed by qualified refrigeration technicians.
If the heat pump enters high-pressure protection specifically during the defrost cycle, check the defrost termination settings.
One possible cause is:
The defrost termination temperature is set too high.
The unit may remain in reverse-cycle defrost longer than necessary, causing condensing pressure to rise excessively.
The termination temperature should be checked against the manufacturer's recommended setting.
For some systems, a value around 10°C may be used, but the correct parameter depends on the model.
Do not apply one universal value to all heat pumps.
Low-pressure protection during defrost may be related to the refrigerant expansion device.
One possible cause is an expansion valve that is:
Depending on the system design, troubleshooting may require:
Because expansion valve adjustment differs significantly between heat pump designs, technicians should always follow the specific manufacturer's service documentation.
The opposite problem can also occur.
The evaporator is relatively clean, but the heat pump still enters defrost mode.
This is known as false or unnecessary defrosting.
Possible causes include:
If the controller falsely interprets the evaporator as being frosted, it may initiate unnecessary defrost cycles.
This reduces heating efficiency because every unnecessary defrost interrupts normal heating.
Check:
If the sensor is defective, replace it.
If the parameter is incorrect, adjust it according to the manufacturer's specification.
This is one of the most important questions for heat pump users.
Usually:
Warning signs include:
The presence of frost alone does not determine whether there is a fault.
Frost pattern, defrost behavior and system performance must be evaluated together.
| Symptom | Possible Cause | Recommended Check |
|---|---|---|
| Ice mainly at evaporator bottom | Poor drainage | Check base pan and drain holes |
| Entire coil frosted, no defrost | Sensor or four-way valve | Check sensor reading and reversing operation |
| Defrost incomplete | Short defrost / low termination setting | Check defrost parameters |
| One side remains frosted | Sensor position or refrigerant distribution | Check sensor location and circuit flow |
| Frequent frosting | Poor airflow | Check fan, coil and installation clearance |
| Frequent frosting + low pressure | Refrigerant shortage/restriction | Check refrigeration system |
| Partial/uneven frosting | Refrigerant distribution problem | Check capillary/refrigerant circuit |
| High pressure during defrost | Defrost termination too high or other system issue | Check settings and operating pressure |
| Low pressure during defrost | Expansion device/refrigerant flow issue | Inspect expansion valve and refrigerant circuit |
| Defrost without visible frost | Sensor/parameter problem | Check initiation temperature and sensor |
Instead of immediately replacing components, use a systematic sequence.
Step 1 — Observe the frost pattern
Is the frost:
Step 2 — Check whether the unit enters defrost
If not, inspect:
Step 3 — Observe the defrost result
Does the evaporator become substantially clean?
If not, check:
Step 4 — Check outdoor airflow
Inspect:
Step 5 — Check the refrigeration circuit
If pressures or frost distribution are abnormal, investigate:
This approach helps technicians move from the simplest external causes toward more complex refrigeration faults.
Many winter frosting problems can be prevented before they become service calls.
Check:
Ensure:
Regularly inspect:
Early detection can prevent a minor frosting issue from becoming a complete evaporator freeze-up.
Yes. Frost can be completely normal during heating operation when outdoor air is cold and humid. The important factor is whether the unit can automatically and effectively defrost.
Possible causes include poor drainage, failed defrost control, incorrect sensor readings, four-way valve problems, insufficient airflow, low refrigerant charge or refrigerant circuit restrictions.
Frequent defrosting may be caused by high humidity, poor airflow, dirty evaporator fins, incorrect defrost settings, sensor problems, refrigerant shortage or incomplete previous defrost cycles.
Uneven frost can indicate uneven refrigerant distribution or a restriction in one of the refrigerant circuits. The refrigeration system should be inspected by a qualified technician.
The defrost initiation temperature may be set incorrectly, or the defrost temperature sensor may be faulty or incorrectly positioned.
Yes. Insufficient refrigerant can lower evaporation pressure and temperature and may contribute to abnormal frosting. However, frost alone is not enough to diagnose low refrigerant charge.
If manual de-icing is necessary, avoid sharp or hard objects that can damage fins or puncture refrigerant tubes. The underlying cause of severe icing should also be identified rather than repeatedly removing the ice.
Evaporator frosting itself is not necessarily a heat pump fault.
During winter heating operation, frosting is a natural result of extracting heat from cold and humid outdoor air.
What determines whether the system is operating correctly is its ability to:
Detect frost → Initiate defrost → Reverse the refrigerant cycle → Melt the frost → Drain the water → Return to efficient heating
When abnormal frosting occurs, technicians should avoid immediately blaming the refrigerant charge or replacing the controller.
Instead, look at the frost pattern.
Different patterns provide different diagnostic clues:
Bottom icing → Check drainage
Entire coil frosted with no defrost → Check sensor and four-way valve
Incomplete defrost → Check defrost duration, termination temperature and sensor position
Frequent frosting → Check airflow, refrigerant condition and fan performance
Uneven frosting → Check refrigerant distribution and restrictions
False defrost → Check sensor and defrost initiation parameters
Good troubleshooting is not simply about removing frost.
It is about understanding why the frost was not removed correctly in the first place.
주소
- 아니34, 사우스 로드, 웅펜 산업단지, Shunde 지구, 포산 528000, 광둥 성, P.R. 중국
Tel
86-757-22860323
