You might check the thermostat. It probably needs replaced. Often times the thermostat will either be stuck in the closed position, causing it to overheat, or in the wide open position causing the heater to blow cold. This is what happened to me. I took the thermostat out and the end was broken off. This made the spring release and be stuck in the wide open position. We were driving over a snowy pass at around 10 pm. NOT a fun trip.
Thermostat stuck in the open position. Replace the thermostat.
Probably your thermostat
No. The thermostat is not likely to be the cause.
Most likely that a valve is installed backwards, or two (or all three) valves are in the wrong position or you are not vibrating your lips in the correct manner
Check into the temperature control valve--this is different than the thermostat.
Sticking thermostat could cause this. If the thermostat is stuck open, it never gives the engine a chance to fully heat the coolant. Follow the top radiator hose to the engine, remove the hose and remove what it hooks to and there's your thermostat.
A thermostat has an Auto position and an On position for the fan's operation. In the On position the switch between Red circuit on the thermostat and the Green circuit is closed, this energizes a fan relay that closes a normally open switch and energizes high/cool speed. On the other hand, the fan relays normally closed switch will go through a time or temp delay, or time and temp delay, that is what controls low/heat speed fan operation. If in cooling you must use the On position to get the fan to run your thermostats bad.
If the thermostat is stuck in the CLOSED position, the vehicle will overheat and may cause a lot of damage. If it is stuck in the OPEN positin, the vehicle may not reach normal operating temperature and the heater may only blow warm or cold air.
Insufficient amount of coolant or thermostat not opening
If your coolant level is fine but your engine temperature gauge is reading on the cool side all the time , your thermostat is probably sticking open. ( or you have no thermostat , or the wrong thermostat - one that has too low of a temperature range ) Anybody else have any ideas ?
How did you change the thermostat?
is there heat to blow or does the blower not work chk thermostat or vacuumn at htr sw respectfully
If it still blows cold when it is at running temp, check the engine thermostat, its probably stuck in the open position.
You may be low on coolant. You may have the wrong temperature thermostat in it.
Thermostat, or fan motor if it does not blow hard.
Make sure you have the right thermostat,
Check the thermostat or heater core
your car will over heat and you might blow your head gasket
Could be a bad thermostat.
you blow it up
it may blow cold air due to the fact that the heat anticipator on your thermostat may be set to long. you can change useing your owners manual for your thermostat but you should have a service tech do it
Running a vehicle without a thermostat will cause it to take longer to warm up and your interior heater may not blow hot air.