Heater not blowing hot but engine not overheating

Does the engine reach normal operating temp? Are the heater hoses hot? If that checks out, maybe a temp door, under the dash has a problem?

first check engine coolant levels, add if low, secondly, check waterpump for proper funtioning, then if the vents are still cold, start looking at the heater hoses for issues and ther is a control valve that lets hot fluid enter the car..if this is locked or stuck you should be able to move the lever by hand and see if it works.. its normally vaccuum operated..good luck

For car running hot and overheating issues, I suggest to you go through this help links. Click this link below and go through the troubleshooting procedure to take care of the problems: ----Car runs hot? http://howtobyme.blogspot.com/2011/11/car-runs-hot-in-traffic.html
-----------All types of car overheating problems and troubleshooting?

http://technoanswers.blogspot.com/2011/11/all-types-of-car-overheating-problems.html
Car freeze overnight and started overheating while driving?http://technoanswers.blogspot.com/2012/01/car-freeze-overnight-and-started.html-----------Engine Overheats and heater blowing cold?

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

---------------------------
Car overheats and Air blows hot at idle?
http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html
--------overheating? http://schematicsdiagram.blogspot.com/2011/12/buick-century-overheating.html
----------Car engine Overheats and transmission starts slipping?http://schematicsdiagram.blogspot.com/2011/12/car-engine-overheats-and-transmission.html
----------This details will help.Thanks.

where did you buy your thermostat? if you bought a fail-safe style thermostat it could have been no good before you even put it in. also is your tempeture gauge coming up to operating temp?? if it isnt your thermostat may be stuck in the open position allowing the coolant to circulate freely and not actually warm up. i would also check the lines going into the heater core. if one line is hot and the other line is cold than your heater core is probably in need of a flush or replacement.

check coolant level in radiator with the engine cool...(take radiator cap off) speedy should have flushed the system for you, might be some crud blocking the heater mech. but most likely low on coolant....good luck to you

Replace the Blower Motor Resistor.It will be located in or near Blower motor box.

Have you checked the coolant level? What you describe is exactly what happens if the coolant level is low. When stopped at idle, hot coolant is not circulating through the heater core, so no heat. As the engine increases in rpm's when you pull away from the light, the water pump is spinning quicker, and some coolant is making it to the heater core. So check the level, and if it is low, keep an eye on it to see if it drops again. That of course indicates a leak somewhere. Get it fixed, as overheating the engine leads to costly repairs and worse case a new engine. Let me know how you make out with this.

sounds like you might have a heater core problem, you also might want to check the thermostat. it may be stuck open

Check to make sure that you have the proper antifreeze level in the radiator first. If this is ok, then I would consider looking at the themostat.

Sounds like you may have a thermostat that is failing or your engine may have had a temporary vapor lock. First of all check your coolant level if that seems fine replace your thermostat. As far as being on high until you shut your heater off is probably just coincidence because when your heater is on it is helping to dissipate the heat from your coolant system.