Be careful you dont over heat soon. I posted this in a different web sight I hope it helps you.
Re: Overheating and blowing cold air I have been a mechanic for 20 years. Your problem is the heater core is
plugged. The cold water from the radiator blows directly at the
thermostat keeping it closed even when you are overheating! BAD
DESIGN!! If you look at the water flow charts in AllData you will
understand. If you rev the motor to 3,000 rpm's the turbulent HOT water
at the water pump impeller (near the thermostat) will reach the
thermostat to open it and the car's temp will fall very fast to the
correct temperature. If you remove the thermostat it will not overheat
but will run way to cold. If you bypass (loop) the heater core it will
not over heat.
The hot water that leaves the heater core returns to the engine at
the thermostat. It is the only hot water introduced to the thermostat
to keep it open and allow the water to flow from and to the radiator. I
normally just back wash the heater core and get large chunks of rust
flake out then its fixed. Back wash then froward wash repeatedly many
times. Also flush out the motor so you don't re plug the heater core. I
hope you have now blown the head gaskets or cracked a head yet. Make
sure to run the proper coolant in the car so you don't promote more
rust flakes. And bleed the air out as mentioned in detail by other
Nobody knows this little secret. Not even Subaru mechanics at the
dealer, no TSB (Technical Service Bulletins a special note after the
fact to mechanics). After days and days of trouble shooting a 1993
Subaru Impreza (2.0?) I looked at the water flow chart and then it was
clear what was happening. This phantom overheating problem stumps the
best mechanics and sends many Subarus to the crusher.
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Most likely it is the heater control valve that shifts air from blowing across your heater core to your air conditioner core.
If your fan works and your car is fairly new..meaning your heater core isn't dirty and full of craap...then it is the climate cotrol valve.
If you are lucky, it might be a thermostat that is bad and blocking hot water from entering your heater core. Bottom line, if hot water doesn't circulate thru that little heater core, you won't get heat.
You might be able to look under the hood and grab the hot water lines that go thru the firewall and feed your heater core. If they feel cold to the touch after engine has warmed up, then you aren't getting circulating water to the heater core. If they feel nice and warm, then the heater core is fine, but your climate control valve has closed off the fan that blows across the core to disperse heat into the cabin
Sounds like a bad heater core. Does the engine temp gauge come up to normal? if it does the locate the hoses that go to the heater and feel them with your hands. If one is hot and the other is cold or barely warm you have heater core issues.
You may have loosened or lost some material into the system while changing the pump and caused a blockage in the heater core. There could be a little coolant going through to warm up but not enough to continue supplying heat once the initial heat is drawn down.
Ideally a back flush through the heater core may take care of it. You should be able to find a kit to help with in an auto parts store.
Open the hood and look on the firewall of the car. There should be 2 rubber hoses going into the firewall and into the car. They will likely have spring clamps just like on the radiator hose. Remove both lines. Then get a hose and put it in one line and run the water until it comes out clear. Then do the same thing with the other side. Do this a couple of times. Then reconnect the 2 hoses ahd check the level of the radiator. Then start the car with the radiator cap off and wait a while for the thermostat to open and have the heater on so it will cycle through the whole system. Then top off as needed.
Could be the diverter valve. It's the one located near the firewall in the engine bay. The valve is in-line on one of the two coolant hoses that run through the firewall. Have a helper rotate the temperature knob back and forth, with the ignition turned on, and you watch to see if the valve is being adjusted. I'm guessing it isn't. Sometimes the cable pops off its perch, other times someting is broken on one end of it or the other. Plastic parts are often used in this assembly. Best of luck
Find where both hoses are going to the heater core from the firewall side after engine is up to temp.Touch them with your hand.If they are both quite warm the water is flowing thru the heater core. If only one is hot the core is stopped up. If both are hot and still no heat the heater door in the heater box is staying closed.
Hello, No! I'm assuming that the temp gauge is working in truck & you are not over heating. On the passenger side firewall check both hoses going to/from heater core. If both are not warm then it is probably a heating core plug. You will have to replace the heater core.
Had same problem. Take off both hoses to the heater core at the fire wall. Using a garden hose with nozel flush with water on the "inlet hose" first(the one hot to touch) then flush the other side. A nasty blackish slim will come out. Oh, cover your distributor with a plastic bag first so it won't get wet. Put the hoses back on, set heat for full high and enjoy your nice warm bravada again!
Verify that the hot water is being circulated thru the heater core by letting the car warm up to operating temp and carefully touching both heater hoses at the firewall where they enter the core. If you are sure that the water is flowing, the the blend door inside the ventilation housing is either not working, stuck, or not getting vacuum. This door directs the air to or away from the heater core depending on the temp control knob position. The system is activated by vacuum pressure, check all vacuum hoses from the engine to the firewall and also underneath the dash on the passenger side behind the ash tray.
The most likely problem is a stuck heater switch. follow the heater hoses from the firewall to the engine block, somewhere along those lines will be a switch that allows the warm coolant to pass through the heater core. place your hand on both sides of the switch with the car warmed up, if the side towards the block is warm and the side towards the heater core cool then replace the switch.