Car low-pressure AC tube freezing can stem from multiple causes, such as refrigerant shortage, a non-stop compressor, excessive water content, or a clogged expansion valve. For instance, long-term damage to the high-pressure hose might allow water to enter through ruptures, suspecting damage to the drying bottle and expansion valve. In such cases, replacing both components and re-evacuating the AC system—for over 20 minutes initially—is necessary before adding the proper amount of refrigerant. However, even after this, the issue might persist during a test run.
Key Symptoms and Issues
Negative Low-Pressure Gauge Reading
When the expansion valve and low-pressure pipeline freeze, the compressor can suck the low-pressure hose flat. Then this causes the AC’s low-pressure reading to go negative. Yet, the compressor keeps running without stopping, exacerbating the problem.
Collapsed Low-Pressure Hose
The frozen components and negative pressure can physically collapse the hose. Then it will block refrigerant flow and worsen the freeze-up.
Resolution Steps
Thorough Component Cleaning
Remove and clean the expansion valve, condenser, compressor, and related AC hoses to eliminate trapped water and debris.
Water Removal from Hoses
Ensure all moisture is purged from the AC hoses, as residual water can reignite freezing issues.
Reassembly and Debugging
After cleaning, reassemble the system and conduct repeated tests. Proper evacuation and refrigerant recharge are critical to restore normal operation.
Role of the Drying Bottle
When washing a car, water can seep into the compressor via damaged pipes. In most cases, if no water is present, vacuuming the system resolves the issue. However, when substantial water enters, simple vacuuming isn’t enough. So thorough cleaning and component replacement become necessary.
Lesson for Repairs
This case highlights the importance of checking for water intrusion during AC repairs. Always inspect for moisture, especially in damaged systems, to avoid recurring freeze-ups. A meticulous approach to diagnosis and cleaning ensures the AC system operates reliably.