My heat works on the passenger side and not the drive i've changed the thermostat and still the problem hasn't changed

Does the engine warm up before driving it? I ALWAY start my truck awhile before I drive (so I don't break the valves and so I can have heat). Mainly because it's an 8.0l v10 magnum (it's gigantic).

Ok, here is my take on your problem. As you may already know, it takes a car a few min. to actually warm up to operating temp. When the coolent reaches operating temp. the thermostat opens to circulate the coolent in the radiator. Now, as your drive, the air pushing against your car will actually blow some air through your heating system ducts and into the passenger compartment. Is it possible that your blower fan isn't working? Because while you are stopped, there would be no air forcing its way through your ducts, thus no heat. As your drive, your car gets up to operating temp, heats up, and the air pressure as your drive will blow some heat out into the passenger compartment? On a side note, if your thermostat is stuck in the open position, it would take it forever to warm up since it is circulating ALL the coolent even tho it isn't at operating temp. A thermostat stuck open will take 30 min or more before you actually feel any warmth, if at all in the winter.. your thermostat opens and closes constantly as the engine is running to keep it at its normal temp, usually around 160-180 degrees. If you live where it gets really cold, a thermostat stuck open likely will never get warm. If your blower motor works, and your engine don't overheat, im 98% sure its your thermostat.

what vehicle is it? let me know then perhaps i can help,

if the car is overheating then there is air in the system causing the no heat problem.the overheating problem could be caused by the cooling fan not working at the radiator,or you have a bad thermostat or you have a headgasket problem with the motor.make sure the cooling fan is working this is a common problem if its not working the the motor will usually have to be replaced.if the thermostat hasn`t been changed it could be sticking closed causing the overheat condition so it will have to be changed.if its not either of these then you will have to have a block test done to see if you have a bad headgasket.

Check the over flow tank located in front of the passenger side glove box for water or fluid. When driving the car, listen by the glove box to see if you car hear a boiling sound. If you can hear water boiling or moving, check your heater core to make sure it is not plugged or bad. When the car starts to over heat, does the gauge register that it is getting hot? If it doesn't then check the thermostat to make sure it is not stuck open or closed. If its over heating and the gauge is not showing that the car is running hot before boiling over, then the thermostat is defective or not working. Try replacing it again.

First off, there is a number of reason why u are hearing bubbling noises but first lets address your Fan. I take it that u have a 2 fan setup, when you say " The passenger side cooling fan will not cut in". This fan is associated with the AC, and only comes on when the AC runs. Helps with better air flow thru the condenser which is in front of the rad. Does the AC work?

OK, now for the bubbling noise. First off the noise indicates to me that maybe you still have problems with over heating. Does the fan on the drivers side come on? Where is the Temp gauge at when it does come on? You might have air in the system, which canbe bleed thru a bleeder screw on top of the motor. I found the best way to do this is have the frt of the car elevated abit with the car off when filling the coolant reservoir. Other things associated with over heating, thermostat not opening, or stuck open. Head gasket, possibly exhaust is getting into cooling system, building up pressure which vents when you shut engine off. Hench the sound. Water pump possibly leaking.

It is normal that the fan can run when the engine is off on Kias an Suzukis. Older Fords did it too (Tempo / Escort).

Your car have a broken evaporator, you have to remove the dash in order to change it.

Sounds like possibly a clogged heater core. If you can see the hoses in the engine compartment ( passenger side, they run through the fire wall ), drain your coolant, remove the hoses and try to flush it out with a garden hose also make sure that everything is off of the passenger side floor, if the core is bad or leaking, it will most likely go there.

Did you check your coolant level or was it low and you added to it at some point? If so the system my need to be bleed or worst case the thermostat is going bad.