My 01 Cavalier is overheating. I changed the thermostat and do not see any apparent leaks. The heater was blowing hot air before I changed the thermostat and now it's only blowing cool air. Any

SOURCE: 1999 Chevy Venture continuosly overheating

sounds like u might have a blown head gasket is your oil milky colored

Paul W

• 404 Answers
• Posted on Jan 16, 2009

SOURCE: 05 silverado running hot

Hi!
Look like you may have an air lock.
Put the car on level ground, start it from cold with the coolant filler cap off, have plenty of warm/hot water available.
Leave to idle watch the coolant filler area but NOT TOO CLOSE, when at operating temp it may appear to boil over loads of bubbles, gurgling and some steam, top the coolant system up with the warm water wait until things settle then replace cap you may have to do this a couple of times.
Remember your anti freeze?
Good luck!
Paul 'W'
Onyer~EDson(:0) {#><U.K.

SOURCE: Blowing Cold Air

It sounds like you need to do a process of elimination, by following the travel of the hot coolant.

1. Before beginning, safety must come first, so put on a pair of safety glasses/goggles and a pair of gloves.

2.Open the hood and check the coolant level, and add if needed. If you needed to add then recheck for heat after step # 3

3. Close the hood and start and run the engine to normal operating temp.

4."TURN THE ENGINE OFF"

5.Reopen the hood and lightly grasp the top radiator hose feeling for heat caused by hot coolant in the hose. Also feel the bottom radiator hose for heat, (you may have to access the bottom hose from under the car) (while down there look for coolant leak...dripping) If heat is somewhat equal between the two hoses move on. If not there are three areas to check
A) Your thermostat may not be opening
B) Your radiator might be obstructed/clogged
C) Your water pump may not be functioning

6. Locate the two smaller hoses that lead to and from your heater core (a small radiator type device located inside cab under the dash that connects through the firewall) (one is connected at the water pump to the heater core the other is connected at the engine to the heater core) one hose may have a regulator (a small mechanical device operated by either cable,electric,or vacuum that controls the flow of coolant into the heater core) attached inline

7. With the hood raised, restart the engine and adjust the heater control to max heat. Locate a safe area under the hood (free of all moving parts) to access and grasp each of the smaller heater hoses, check for heat, caused by hot coolant in the hose, also check the hose before and after the regulator described in step # 6.
If either of these locations are cold to the touch we can safely say we have narrowed the problem down to one or all of three things.

A) If all heater hoses are cold or only the inlet side of the regulator is hot and the other side is cold or warm, its possible that the regulator is faulty requiring a replacement or is not functioning due to inadequate cable,electric,and/or vacuum to operate it caused by a broken cable, electrical short or disconnected/ broken vacuum line, it also could be a defective (in dash) heater control unit or just a fuse if its electrically operated.

B) If the inlet hose to the heater core is hot and the other outlet hose is cold or warm then its possible that the heater core is obstructed/clogged, requiring a flush out or replacement.

C) If all heater hoses are hot (you may also feel a flow vibration in the hoses) then you should have heat, unless the under dash duct work is disconnected or blower fan is not operating.

I hope this helps.....

SOURCE: blowing cold air

I had the same problem that I just fix by flushing the heater core out with a hose.   take the two hoses off the fire wall and put the water to it and let flush.  my heater is putting out 150 dg. F  of hot air.   I'm so excited!  i will stay warm now.

SOURCE: 2002 chevy cavalier is over heating but running

R the fans blowing, make sure its full of water...waterpump may be bad

Testimonial: "fan wasnt blowing at first then started to... water pump huh? thats what i am hearing from many"