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

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Component Tests






Pressure & Temperature Charts:





1. Connect manifold gauge set to system.
2. Start engine and turn A/C system ON.
3. As soon as system is stabilized, record high and low pressures as indicated by manifold gauges.
4. Low side pressure should be 20-41 psi, and high side pressure should be 185-263 psi.
5. As low side pressure drops, high side pressure should rise. As low side pressure rises, high side pressure should drop.
6. Record center duct temperature.
7. Determine and record ambient temperature.
8. Compare test readings with chart.