Our complete Armstrong air conditioner repair guide, from how to replace your air filter, common issues, to troubleshooting tips, and more!
Please note, the following is for informational purposes only. Any servicing you attempt is at your own risk.
Table of contents
Armstrong At a Glance
Armstrong got its start in 1928 and earned a fast name as a trusted and reliable brand. They are committed to learning and innovating their HVAC solutions, and it’s an important part of their ethos that they produce durable units that provide comfort for homeowners. Each product goes through testing and tweaking to create a solution that their technicians would install in their home.
Hard work and passion goes into the creation of your Armstrong air conditioner, but that doesn’t mean it’s not susceptible to regular mechanical issues like any other unit. There are tasks that you can do as a homeowner to maintain your unit and keep it running at top efficiency for years to come. Check out some of the ideas below to see how you can make maintenance part of your seasonal routine.
How to Replace Your Armstrong Air Filter
Replacing your filter is a quick and straightforward task that is a great job to do since it’s a small action that can have a big impact on the way your air conditioner works in the future. A clean filter is one that can consistently, and efficiency circulates and cool air throughout your home; if it’s dirty, that adds stress that can cause damage and early failure of your unit.
- Locate your air filter. Typically, it will be in the furnace, air conditioner or the return duct. Switch off the power to your air conditioner before you take out the filter.
- Pull out the filter. Clean it if it’s a reusable filter or replace it with a new one. When you replace the filter, ensure that the airflow arrows are in the same direction as the airflow of your air conditioner.
- Close the housing for your air filter and turn the power back on to your unit.
Other General A/C Maintenance Tips
Maintaining your unit is one of the best things that you can do to ensure the longevity of your air conditioner. There are a lot of easy tasks that you can carry out as a homeowner that won’t take too much time or effort. With a little patience and your owner’s manual, you can keep your air conditioner running efficiently for years. Make sure to turn off power to your unit before opening it.
1. Clean around your unit
Take care to ensure that the two feet around your unit are free of debris like leaves and plant growth. Trim back excess flora and remove anything near or on your air conditioner so that air can flow freely.
2. Clean and straighten the fins
The fins can be cleaned by using a garden hose on a gentle spray setting and spraying from the inside out to remove debris and dust that is trapped. Avoid using too much pressure because you may damage the delicate fins. To straighten the fins, you can try a fin comb from a hardware store or use a butter knife carefully to put the fins back in place.
3. Level your unit
If the pad that your unit is resting on has tipped due to soil flattening underneath, the uneven tilt can cause the compressor to fail or become damaged. Fix the pad your unit is on until it rests evenly on the ground.
What’s Wrong With Your Armstrong Air Conditioner?
Remember to turn your A/C completely off before opening it up to look around or attempt any fix.
Armstrong Air Conditioner Error Codes
Note that these error codes may or may not be accurate or apply to your system. Each manufacturer has a range of different sensor and error codes used for different model lines and these may differ from one model series, production run, region, and may have been updated at any time. This not a comprehensive list and these are for informational purposes only. Any use of them is at your own risk.
Error Codes
| Alert Codes | Inverter Codes | Red LED Flash Code | Green LED Flash Code | Priority | Description |
|---|---|---|---|---|---|
| E345 | N/A | N/A | N/A | Critical | Heat Pump or Air Conditioner Alert Code - The "O" relay on the outdoor board has failed. Either the pilot relay contacts did not close, the relay coil did not energize or the circuit that confirms this operational sequence is not sensing properly. |
| E409 | N/A | N/A | N/A | Moderate | Outdoor control secondary voltage is 18VAC or less. |
| E410 | N/A | N/A | N/A | Moderate | The outdoor unit cycled off due to low pressure switch opening. |
| E411 | N/A | N/A | N/A | Critical | The low pressure switch has opened 5 times within one hour. As a result, the outdoor unit is locked out. |
| E412 | N/A | N/A | N/A | Moderate | The outdoor unit high pressure switch has opened |
| E413 | N/A | N/A | N/A | Critical | The high pressure switch has opened 5 times within one hour. As a result, the outdoor unit is locked out. |
| E416 | N/A | N/A | N/A | Moderate/Critical | The outdoor coil sensor has malfunctioned. As a result the outdoor unit control will not perform defrost. |
| E422 | N/A | N/A | N/A | Moderate | Compressor top cap switch exceeding thermal limit. |
| E423 | 40 | 4 Flashes | OFF | Moderate/Critical | The inverter has detected a circuit problem |
| E424 | N/A | N/A | N/A | Moderate | The liquid line temperature sensor has malfunctioned |
| E425 | N/A | N/A | N/A | Minor | Outdoor control has increased minimum compressor speed to allow for proper oil return due to low ambient temperature. NOTE - Minimum speed adjustments begin at 45°F and increase to 100% minimum at 17°F. |
| E426 | N/A | N/A | N/A | Critical | Excessive inverter alarms |
| E427 | 21 | 2 Flashes | 1 Flash | Moderate/Critical | The inverter has detected a DC peak fault condition. If condition (55A or higher) is detected, outdoor unit compressor and fan stop. Anti-short cycle is initiated. If peak current (55A or higher) occurs 10 times within an hour, system is locked out. Indicates high pressure, condenser fan failure, locked compressor rotor or overcharge. To clear, disconnect power to outdoor unit and restart. |
| E428 | 22 | 2 Flashes | 2 Flashes | Moderate/Critical | The inverter has detected a high main input current condition. |
| E429 | 23 | 2 Flashes | 3 Flashes | Moderate/Critical | On a call for compressor operation, if DC link power in inverter does not rise above 180 VDC for 2 and 3 ton models, 250 VDC for 4 and 5 ton models, within 30 seconds, the control will display a moderate code. If condition is detected, outdoor unit will stop (Compressor and fan). Antishort cycles is initiated. If condition occurs 10 times within a 60 minute rolling time period, system will lock out and display a critical code. |
| E430 | 26 | 2 Flashes | 6 Flashes | Moderate/Critical | Compressor start failure |
| E431 | 27 | 2 Flashes | 7 Flashes | Moderate/Critical | Error occurs when PFC detects an over-current condition of 100A, the control will display a moderate code. If condition is detected, outdoor unit will stop (Compressor and fan). Anti-short cycle is initiated. Inverter is unavailable to communicate with the outdoor control for 3 minutes. If condition occurs 10 times within a 60 minute rolling time period, system will lock out and display a critical cod |
| E432 | 28 | 2 Flashes | 8 Flashe | Moderate/Critical | The inverter has detected a DC link high voltage condition. |
| E433 | 29 | 2 Flashes | 9 Flashes | Moderate/Critical | The inverter has detected a compressor over-current condition |
| E434 | 53 | 5 Flashes | 3 Flashes | Moderate/Critical | Outdoor control has lost communications with the inverter for greater than 3 minutes. Outdoor control will stop all compressor demands, recycle power to the inverter by de-energizing the contactor for 2 minutes. If this occurs 3 time in one thermostat call, the outdoor unit will locked out and display a critical code. |
| E435 | 60 | 6 Flashes | OFF | Moderate/Critical | Inverter internal error. |
| E436 | 62 | 6 Flashes | 2 Flashes | Moderate/Critical | Inverter heat sink temperature exceeded limit. Occurs when the heat sink temperature exceeds the inverter limit. Inverter issues code 13 first, then slows down to allow the heat sink to cool. If temperature remains high, outdoor unit stops (compressor and fan). Anti-short cycle is initiated. If condition occurs 5 times within an hour, system is locked out. To clear, disconnect power to outdoor unit and restart |
| E437 | 65 | 6 Flashes | 5 Flashes | Moderate/Critical | Heat sink temperature sensor fault has occurred (temperature less than 4ºF or greater than 264ºF after 10 minutes of operation). |
| E438 | 73 | 7 Flashes | 3 Flashes | Moderate/Critical | The inverter has detected a PFC over current condition. This would be caused by a high load condition, high pressure, or outdoor fan failure. Outdoor control will display the code when the inverter has the error. After 3 minutes, the inverter will reset and the compressor will turn on again. If it happens 10 times within a 60 minute rolling time period, the OD control will lock out operation of the outdoor unit and display a critical code. |
| E439 | 12 | 1 Flash | 2 Flashes | Moderate | Compressor slowdown due to high input current. |
| E440 | 13 | 1 Flash | 3 Flashes | Moderate | Heat sink temperature is approaching limit. The compressor speed automatically slows to reduce heat sink temperature. The control sets indoor CFM and outdoor RPM to values according to demand percentage rather than the actual Hz. Alarm is automatically cleared. |
| E441 | 14 | 1 Flash | 4 Flashes | Moderate | Compressor slowdown due to high compressor current. Compressor current is approaching limit. The compressor speed automatically slows. The control sets indoor CFM and outdoor RPM to values according to demand percentage rather than the actual Hz. Alarm is automatically cleared. |
| E442 | N/A | N/A | N/A | Critical | The top cap switch has opened five times within one hour. As a result, the outdoor unit is locked out |
| E443 | N/A | N/A | N/A | Critical | Incorrect appliance unit size code selected |
| E600 | N/A | N/A | N/A | Critical | Compressor has been cycled OFF on utility load shedding. |
| E601 | N/A | N/A | N/A | Critical | Outdoor unit has been cycled OFF on low temperature protection |
When to Get a Technician for Armstrong Air Conditioner Repairs
Though there is a lot of maintenance that you can do on your air conditioner unit by yourself, there are a few things that are better addressed by a technician. Regular check-ups on your unit can help avoid significant repairs or a possible replacement in the future. If you’re experiencing any of the issues listed below, it’s best to get a professional in to fix your air conditioner.
Frozen coils
Frozen coils typically happen when something has gone wrong in your unit. Determining the issue can be a challenge, as the source of the problem can be with the ducts, drain or internal parts that are dangerous or tricky to see and change.
Clicking sounds
Clicking sounds when your A/C turns off or on can be symptomatic of a relay issue or suggest that an internal part has come loose.
Damaged compressor
A damaged compressor can cause a lot of problems, the main one being that air won’t be flowing properly. This will take a technician to diagnose and repair, as it’s a very involved job.
Leaking refrigerant
Leaking refrigerant is a serious problem that can impact how well your air conditioner can cool your home. You’ll need a certified technician who can address this issue to bring your unit back to efficient standards.
Who to Call for Armstrong Air Conditioner Repairs
Knowing who to contact when your air conditioner is on the fritz can be a difficult decision. How do you know who is reliable and trustworthy, as well as able to carry out the job with skill and competence? You could always check reviews online about independent technicians and companies, but it’s hard to tell how biased these reviews may be. You may end up reading more about the reviewer’s personality than the actual service received.
To help you with this, we’ve created an independent HVAC contractor certification program that you can use to find a certified partner who has been vetted and found to be dependable and trustworthy. This includes that they have a good reputation, all the right licenses and certifications, insurance, manufacturer training, and experience, plus they provide quotes that are accurate and transparent.
If you’re looking for a recommendation, don’t hesitate to reach out. We want you to be fully informed before inviting someone in to work on your air conditioner.
Armstrong’s Warranty Coverage
Armstrong’s warranty is the same across all models of their air conditioning line, offering good coverage for their units.
When you register within 60 days, you’ll get a 10-year limited warranty on parts. If you don’t register online before the time, you’ll get the default 5-year warranty.
Protect your Armstrong air conditioner: Register and access your Armstrong A/C warranty here
