You have two issues.
On that car, you likely have a heater valve stuck. That valve is supposed to divert hot radiator water to the heater located in the passenger compartment. You must replace the heater valve.
The over-heating issue is a different issue entirely. That could be caused by a lot of things:
1. Bad fan clutch
2. Broken fan blade
3. Obstruction of air through the radiator (plastic bag sucked into the radiator grill?) Have you seen the cat lately and does the radiator make meowing sounds?
4. Clogged water tubes in the radiator. This would likely require a replacement radiator because they are plastic now a days, unlike metal radiators that could be rodded out or re-cored.
5. Pinched bottom radiator hose (if the spring inside of it rusted and collapsed).
6. Stuck thermostat. This is the most likely problem, also the cheapest and easiest solution. It is located where the upper radiator hose meets the engine block, and it comes out with just two bolts. You'd need a new thermostat (about $15) and a new gasket (about a buck or two), and some high temperature gasket glue (at a car parts store for about $5/tube).
7. Exhaust gas in the radiator water (from cracked block, cracked head, or blown head gasket?).
Still a big air pocket in the engine, you want to pull the car up onto ramps to get the front of the engine higher, pop the radiator cap off and let it run and the air bubbles should escape.
Turn on the heater while doing this so it can clear any out stuck in there too.
Keep an eye on the coolant level, it could take 30 mins.
I vary the idle speed and rev it to 3k rpms a few times to clear the thermostat of trapped smaller bubbles.
Good Luck :)
stuck thermostat. the heater core is not getting coolent. air locks ect or flushing can cause a boderline thermostat to go bad or stick
Could be any of the things that have been mentioned, if you never had a problem until you flushed the radiator, then I'd say probably an air pocket. If you were having problems then, could reasonably be your thermostat, or a heater core issue.
Personally, I once had a car that would occasionally overheat and never blew hot air unless I was in neutral and revved the engine.
Ended up being a head gasket leak, but it was blowing combustion air into the coolant. Crazy. Drove it that way for a year before it actually crapped out.
That certainly sounds like the heater core is blocked, at 135,000 and 11 years old that is not surprising if you failed to change the coolant ever 2 years, which few people really do.
i have a 2003 acura rsx with 135000 miles. Today I flushed the radiator and replaced it with new coolant (the do not add water type). After I left the radiator cap off and let the engine run for 15 to remove any possible air pockets. After 2 blocks of driving I noticed that the engine was 3/4ths hot and climbing so i turned it off and pulled to the side. When i turn on the heater it blows cold air. What could the issue be?
