2003 impala heater quits working sometimes and it overheats sometimes

It could be a number of things:
a. Radiator partly plugged, check to see if water circulates with engine running and cap off.
b. Thermostat not opening
c. Heater plugged.
d. Anti-freeze low in radiator
You can feel the heater hoses and see if water is circulating or if hoses are hot water is going through them.

sounds like you need to replace the heater core

sounds like you have a clogged heater core

one possibility either the cruise control is on the same circuit line with the heater/defroster fan and same fuse. try to solve the problem with the fan and you will notice the difference.

To troubleshoot this types of problem,click the link below :----http://howtobyme.blogspot.in/2012/02/heater-blows-only-from-defrost.html
--------Go through the procedure to confirm the issue.

------
Engine Overheats and heater blowing cold?

http://howtobyme.blogspot.com/2011/11/engine-overheats-and-heater-blowing.html

---------
Heat blows cold on drivers side and hot on passenger side?

http://schematicsdiagram.blogspot.com/2011/12/heat-blows-cold-on-drivers-side-and-hot.html

-----------

No heat on car? http://technoanswers.blogspot.in/2012/02/no-heat-on-oldsmobile-silhouette.html

------------
Heater blows intermittently and temp gauge goes erratic? http://technoanswers.blogspot.com/2012/01/heater-blows-intermittently-and-temp.html------------Heater blows cold? http://schematicsdiagram.blogspot.in/2012/02/heater-blows-cold.html
---------Car heater blowing warm, but not hot air? http://schematicsdiagram.blogspot.com/2011/12/car-heater-blowing-warm-but-not-hot-air.html-------- Heater/AC blower motor not working?

http://technoanswers.blogspot.in/2012/02/heaterac-blower-motor-not-working-on.html

------------
A/C, heater, defroster fan, not working? http://technoanswers.blogspot.in/2012/02/ac-heater-defroster-fan-not-working.html Heater problem? http://technoanswers.blogspot.in/2012/02/heater-problem-on-isuzu-trooper.html---------

This will help.Thanks.

The first thing to check is the coolant level. The coolant can get low enough to affect the heater, but not overheat the engine. Check the coolant tank and the radiator itself, when the engine is cold.
If coolant full, then you may have trouble. may be an actuator under the dash, temp control, computer?

Have u checked the coolant level? this type of problem useualy indicates the coolant is low, if it is low you need to have the engine cooling system tested for a leak, the coolant goes out somewhere.

common impala problem friend of mine has a 2000 with the same problem just cover the grill so that cold air does not blow into the rad it should give you your heat back

sounds like a leaking head gasket

If its a whining noise, it could be a belt slipping. If its more of a grinding noise, the blower motor could have a bad bearing or something has found its way into the area around the fan. You'd have to figure out where it is coming from. If it sounds like its coming from under the dash, its probably the blower motor.