Why isn't my heater in my car getting warm

First, check the coolant level. If it's low, your heater core will be the first thing to starve of coolant. If it's ok, check the running temperature. You probably don't have a heat gauge, but if the heater hoses aren't getting hot, you likely need to replace the thermostat. It's at the base of your upper rad hose under a housing held by two bolts.

Check the heater matrix valve firstly for it's valve operation and cable operation. Also check that the heater matrix isn't clogged with hair and gunk. this can dramatically affect how much air can blow through it.Check that the pipes leading in and out of it are hot from the engine. If not, then check your engine for coolant leaks, blockages and running temperature. If your engine isn't getting up to heat, then neither will your heater. This could likely be a thermostat which has failed.

you need to first check the operation of the valve on the heater matrix.
The heater matrix is situated in the centre of the inside of the fire wall, or in other words, behind where the stereo normally is situated on the majority of cars.
Find the heater matrix, which will be surrounded by some plastic shrouding, and inspect the operation of the valve mechanism while you play with the heater adjustment.
If the valve is moving, and if the matrix is warm or hot, then the valve innards may have failed.
If it isn't moving however, then the issue is either with any driver motor or any cables or dials which are linked if using a manual style operation.

This is not a heater valve problem, for one thing there isn't any such part in the model. The problem is a defective air temperature control blend door inside the air ducting.

Hello! There are only a few reasons for this awful event to occur in early December...Either Hot water isn't circulating through the heater core, the thermostat isn't opening or the door that directs heat is faulty...Is the temperature gauge showing normal? Next, is the upper radiator hose hot and hard? If the last two answers are yes then hot water is circulating...The unit that controls the doors ...ie...heat or defrost is called an Actuator...Also the lever that opens the heater may be at fault....LETS ELIMINATE...
Is there defroster heat? If no the heater core isn't opening ..If yes then the actuator is the culprit...You can check the heater by feeling of each of the two hoses that come through the firewall into the inside...If they are both hot then the heater core is open and functioning...If one is cold the heater isn't being opened by the temperature control..Or it is simply blocked with gunk....It's a 99 and getting old...I would suspect that IF the upper radiator hose is hot and hard and the temperature gauge is normal all is well with with most components and the next step is; Are both heater hoses hot...Your going to have to narrow this down for me to pinpoint the cause...See diagram below of the door actuator allowing defrost heat to be sent to the heater floor duct...
Send a comment with results and or observations...Remember"your my eyes and my hands"...Guru ...Saailer





I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

You definatly have water inside the car. Pull the carpet back in the front and rear checking for water leaks. The only way frost can develope inside a vehicle is the presents of moisture.
The other possibility is your HVAC drain is plugged and water has built up inside the heater motor area. Have the drain checked and cleaned.

Without more information, I can tell you that you have a problem with your heater core. Check coolant levels and make sure you aren't low on coolant. If that isn't an issue, make sure your heater core isn't bypassed. In Texas, I see them bypassed instead of repaired because it hardly ever gets cold here. You could also have a dirty heater core that isn't allowing the heat transfer. The only other thing it could be is an issue with the temperature blend door/actuator. If it isn't opening properly to allow the warm air from the heater core to enter the ventilation system, you won't get hot air.

first it to verify the coolant flow. I suspect the heater core isn't flowing, you may need to take a garden hose and take both heater hoses off, and flush in both directions to clean the heater core. flush in both directions until you get clean water flow. I am assuming the coolant level is OK, and the water pump is pumping and the engine is getting warm enough.

Sensor 2 Bank 2 is the left rear oxygen sensor. It problably is bad
and needs to be replaced before your next inspection. The rear oxygen
sensor just monitors what is coming out and isn't as important as the
front oxygen sensor. The car will still run properly if you don't
replace it but will not pass inspection, in most states, if you don't
replace it. The part is inexpensive (about $30) but is hard to
replace without the proper tool. They make a special socket for
replacing oxygen sensors. You should be able to pick up the socket
for $15-$20. It has an opening for the attached wire. You could try
to remove the old one with an open ended wrench but you will probably
strip it. It's a 22 mm or 7/8 inch.

Your problem can be caused by a bad thermostat, bad heater control valve, a heater door that's not opening or a clogged heater core. If the thermostat is good, check your heater hoses when the heat is on. Both should be hot; if one isn't there is a vacuum operated device inline with one of the hoses (heater control valve) make sure the vacuum line is connected to it. Sometimes you can manually force the valve to move; if you can do it and see if the 2 hoses get hot as a result. If they do, change the valve. The heater door is inside the vehicle and it too is usually vacuum controlled and often somewhat involved to service. I'm not sure of the exact configuration of your heater core but they too can become very involved to replace. More than likely the heater core isn't clogged and there's a very good chance you just have a sticking heater control valve.