I installed a new blend door a new heater core and still have no heat. it iwll blow hot and then start blowing cold air after about 3-5 seconds. I was told the acuator may need to be callibrated to my computer is this true. I spent 1258.00 including a new a/c evaporator and still have the same problem. temp gauge is showing 1/2 when vehicle gets warm so i know the t stat is opening . I need help It is November and I am in Michigan
Did you check the blend door motor? they will break and cause the door to not move. the dealer can run it thru a mode/blend door test. They just try to move the door with the obd computer they can calibrate them as well.
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You have one of two problems. The heater core is plugged /
restricted or there is an inoperative internal blend door motor problem. Start the vehicle and let it reach operating temperature. Feel the hoses under the hood that go into the heater core. They should be close to the same temperature. If one is hot and the other luke warm/cold.... the heater core is plugged/restricted. If both hoses are near the same temperature, suspect a defective/non operational blend door motor that controls heat/cold/airflow attached to the heater box assembly
If both heater hoses are hot, then coolant is coming and going into/out of the heater core. The only thing that would affect heat would be a blend door not operating correctly. You will have to check the proper door that controls hot/cold air.
1. Check coolant level to ensure full, and thus getting to heater core. 2. If that didnt work, With engine hot and running, and heat on in the truck, feel heater core inlet and outlet hoses at the engine compartment firewall to ensure both are hot an thus getting flow. If not the core is clogged or there is a faulty valve in the flow path. 3. If te hoses are hot there is flow thru the core and either your blend door is broken and shut or the blend door motor or circuitry is bad. 4. You tube Ford Ranger blend door for video on how to access behind the glove box. You can fairly easily remove the motor and undoing so check its operation and also the blend door operation. Likely your motor has gone bad and can be replaced using a low profile socket wrench to remove the 3 Screws holding it in place. I bought a new motor for $40 at One o te auto parts chains locally. Good luck!
I like that you were knowledgeable to check both coolant lines tells me you are getting hot coolant through the heater core next thing to check will be the blend door on the inside of your vehicle. The blend door is a door that switches from cold air duct to heater duct depending on what you are using at the time. If it is stuck on the cold air duct you will not get any heat sometimes these doors are vacuum actuated and sometimes they are electrically actuated most the time you are able to see the movement of the motor from inside if you don't see any movement but you hear it move chances are it is the door blend I hope this helps.
Temperature Control Blend Door Failure No Heat or no AC (dependes on
where door sticks)
all modern cars there is a tiny DC electric motor driven gear drive
that moves a plastic door that blends heated and cooled air from the
AC and the heater core, this is called (interestedly enough) the air
temperature control blend door actuator. The motor that moves this
door fails because the door starts sticking from warping, most common
complaint is no heat but it can be no AC as well. To replace these
parts (blend door and blend door actuator) you must remove the entire
dash from the car. Always have this problem confirmed by a dealer or
qualified repair shop as it is a very expensive repair.
causes of no heat in the cabin are engine thermostats that are stuck
open (engine runs cold) or air bubbles in the cooling system.
Check for correct coolant mixture. Also you could have a thermostat that is stuck completely open causing it to flow straight threw the engine block, cylinder heads, heater core, an radiator without stopping long enough to heat the coolant up to provide cab heat. It could also be a clogged heater core. Or a blend door on the HVAC box that is not allowing the heater core door to open. Hope this helps.
Most likely the problem is a broken blend door inside the heater box or a broken adjuster cable going to the blend door, the blend door inside the heater box is responsible for heater output depending on your temp adjustment on your heater control panel, most likely the blend door is stuck in the cold position allowing cold air to come through the vents verses allowing the blower motor to blow warm air past the hot heater core to produce heat, check the temperature adjuster cable behind your heater controls and make sure its connected and not broken, lastly make sure the blend door isnt broken and operating freely.
first feel the heater core hoses see if both are hot if so then your problem is in the blend air door must be stuck on cold. is your blower motor blowing cold air if not your blower motor might be the problem. the blend air door is down by the blower motor.
First you have to identify what causes the problem.
To do this you have to: 1)When engine is cold check the level of coolant. If it is low fill it up. 2)Start engine and check if engine reaches regular temperature. If your engine is not heated enough it means your thermostat does not work properly and should be replaced. 3)If engine temperature is normal, then check the temperature of pipes that go to/from heater core. These pipes are located up the fire wall (easier access is from the passenger side). If pipe/pipes are cold (even engine is worm) it means you heater core is plugged and should be flushed. Keep in mind, flushing the whole cooling system is different from flushing heater core. 4)If pipe/pipes are hot/warm, turn off the fan, switch controller to the hot position, wait for 3-4 minutes and turn on the fan. Note if the cold air blows first or warm air blows first but it cools down in 5-10 seconds. If the air blows cold than it is most probably the problem with blend door or blend door actuator. 5)If air blows warm first and then cools down, then while running engine and remaining the transmission in PARKING position, press on the gas pedal until your engine reaches 3,000 RPM. Check if your heater blows warm/hot air. If it does, then your water pump does not work properly and should be replaced. If the air still cold, I would suggest to flush the heater core.
Sounds like a stuck heater core valve. Find heater core valve. Under hood, find the two heater core hoses going into firewall. One of the hoses has a valve. Operate temperature control (full heat, then full cold) check that valve changes position. If not either replace valve or control system failure. Also, when temperature control in cold position, one hose should feel hot and the other cold. Temp fix: disable valve to close no heat or on heat.