Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

Or, hide this message: temporarily or permanently

Service Port HVAC: Description and Operation

Gauge Port Valves

The high-pressure gauge port valve is located on the condenser-to-evaporator line.
The low-pressure gauge port valve is located on the A/C manifold and tube assembly.




The fitting is an integral part of the refrigeration line or component.
- Special couplings are required for both the high-side and low-side gauge ports
- The Schrader-type valve core can be repaired if the seal leaks
- Always install the A/C charging valve cap on the gauge port valves after repairing the refrigerant system.