
Yes, you can use silicone hose for certain car vacuum lines, but it is generally not recommended for the critical air conditioning evaporator lines due to potential permeability issues with the refrigerant. While silicone offers excellent heat resistance and durability, its porous nature can allow small refrigerant molecules to escape over time, leading to a gradual loss of system charge and reduced cooling performance. For most standard vacuum applications, high-quality, reinforced silicone hose is a reliable and long-lasting upgrade over OEM rubber.
The primary advantage of silicone hose is its superior resistance to heat, ozone, and cracking compared to standard EPDM rubber. This makes it an excellent choice for vacuum lines in engine bays where temperatures are consistently high. However, for the A/C system, which operates under high pressure and contains specific refrigerants like R-134a or the newer R-1234yf, the material's permeability is a significant drawback. OEM rubber hoses are often lined with a special nylon or polyamide layer specifically designed to act as a barrier against refrigerant leakage.
Here’s a quick comparison of key properties:
| Property | OEM A/C Hose (Barrier Lined) | Silicone Vacuum Hose | Notes |
|---|---|---|---|
| Refrigerant Permeability | Very Low | High | Silicone can lose several ounces of refrigerant per year. |
| Heat Resistance | Good (up to 250°F) | Excellent (up to 350°F+) | Silicone wins in high-temperature environments. |
| Pressure Handling | Excellent (500+ PSI) | Good (Varies by reinforcement) | A/C systems require high burst pressure ratings. |
| Flexibility & Durability | Good | Excellent | Silicone is less prone to hardening and cracking with age. |
| Cost | Moderate | Moderate to High | Silicone is generally more expensive than basic rubber. |
If you are replacing a simple vacuum line for a brake booster, PCV system, or emissions control, a properly sized silicone hose is a great choice. For any part of the sealed A/C refrigerant circuit, including lines to and from the evaporator, it is crucial to use hose specifically rated and designed for automotive air conditioning service to maintain system integrity and efficiency.


