Posted: Sat Dec 11, 2010 6:10 pm Post subject: 2007 Impala heater trouble
2007 Impala 3LT, 3.9 engine, 73,000 miles. This problem just started this year. I get cool air blowing at idle. The temp gauge goes to operating temp just as it always did, points at the 9 o'clock position, and warms up normally. When driving the heat works great, just as it always has. But at an idle, the heat blows cool. If I rev it to 2000 RPM, hot air blows. Both heater hoses feel the same temp. I just had the cooling system professionally flushed, and they backflushed the heater core, which didn't seem to have any restriction. The system had the air bled out, and they even poured coolant right into the heater hoses until it ran out. Dexcool was NOT reused. No help at all. Coolant level full. Even sitting still running it to 2000 RPM gets nice hot air. Any ideas? Water pump not leaking, and bearing is quiet and no play, can the impeller be worn and no circulating coolant? The shop said the coolant still looked good.
_________________ 2007 Impala 3LT, 3.9 AFM.
Last edited by Oldrustycars on Sat Dec 11, 2010 9:41 pm; edited 1 time in total
Did you change the t-stat while you were in there? Might be worth a shot.
Engine warms up just as quick as it ever did. Comes up to temp in 10 minutes even at 5 degrees out. Shop felt if the thermostat was bad it would either run very cool (it doesn't) or overheat (it doesn't). But thanks for the idea.
Joined: Dec 20, 2010 Posts: 1 Posts per day: 0 Location: Madison, WI
Posted: Mon Dec 20, 2010 2:01 pm Post subject:
I have had a similar problem on an 06 with a 3.9, there is a small coolant leak somewhere and the reason you don't have heat is because you are low on coolant. The car I was working on I topped off with coolant and the heat worked amazing at any rpm. Your overflow tank needs to be at least 1/2 full. The reason you dont have heat at idle is because when you are at a higher rpm you are circulating coolant faster and forcing it to circulate through the entire system. When you are at an idle fluids flow in the path of least resistance and your heater hoses are smaller then the main coolant passages, therefore you are not circulating to your heater core when at an idle, top off your overflow.
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