Some 2007-09 Saturn Sky Redline models may come into your with the overheat warning lamp on and/or insufficient heat coming from the heater vents.
One likely cause, reports GM, is an airbound cooling system. The air frequently ends up as pockets in the heater core, which results in the lack-of-heat complaint.
Installing a new check valve, part No. 20876185, into both ends of the coolant return hose should eliminate the trouble. When installed properly, the check valves should be positioned vertically, with the tapered ends facing the nipples of the engine port and radiator.
"Factory Fixes" is written by Jim DePalma, a 30-year veteran of the auto repair business who has served stints as a service manager, parts manager and ASE-certified technician. His column provides vehicle manufacturers' authentic factory technical service bulletins (TSBs) that have been condensed for easier reading. Mr. DePalma advises that techs always check with a dealer or repair information system for the latest revisions before starting to work on a vehicle. He can be reached via email at [email protected].