Chevrolet HHR 2011 Owner's Manual page 303

If no coolant is visible in the coolant recovery tank, add
coolant at the pressure cap as follows:
Turn the pressure cap slowly counterclockwise.
If you hear a hiss, wait for that to stop. A hiss
means there is still some pressure left to be
vented.
2. Then keep turning the pressure cap and remove it.
3. Add the proper DEX-COOL coolant mixture to the
coolant fill port, up to the base of the port. See
Engine Coolant on page 6 24 Engine Coolant for
more information about the proper coolant mixture.
1. Remove the pressure
cap when the cooling
system, including the
pressure cap and
upper radiator hose,
is no longer hot.
4. Rinse or wipe any spilled coolant from the engine
and the compartment.
5. Then fill the coolant recovery tank to the COLD
FILL (A) line.
6. Put the cap back on the coolant recovery tank, but
leave the pressure cap off.
7. Start the engine and let it run until you can feel the
upper radiator hose getting hot. Watch out for the
engine cooling fan.
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