I would start with checking the blend door under the dash that controls temp.
SOURCE: temp control switch does not regulate temp i get heat on all settings except max ac
switch prolly not bad but you might wanna look into your heater control valve. valve not closing and letting the hot coolant fill your heat exchanger rather than recycling it back to the cooling system. The heat is over powering your a/c system and you're only getting a bit of cooling when you have the a/c on max. try it out
SOURCE: 97 Ford Ranger no heat
I may be missing something here, but first and formost, check the antifreeze (when the car is cold) and see if you have enough in the radiator. Next, consider the thermostat. Finally, check to see if the dampers are opening up to allow heat to travel into the cab. I suspect it is not related to the A/C.
SOURCE: 1995 ford ranger with 4.0 auto, I have very
Hi. There are several ways to test the opening temperature of a thermostat. Use this procedure to confirm that you are running the correct rated thermostat.
One method does not require that the thermostat be removed from the engine.
* Remove the radiator pressure cap from a cool radiator and insert a thermometer into the coolant.
* Start the engine and let it warm up. Watch the thermometer and the surface of the coolant.
* When the coolant begins to flow, this indicates the thermostat has started to open.
* The reading on the thermometer indicates the opening temperature of the thermostat.
* If the engine is cold and coolant circulates, this indicates the thermostat is stuck open and must be replaced.
The other way to test a thermostat is to remove it.
* Suspend the thermostat completely submerged in a small container of water so it does not touch the bottom.
* Place a thermometer in the water so it does not touch the container and only measures water temperature.
* Heat the water.
* When the thermostat valve barely begins to open, read the thermometer. This is the opening temperature of this particular thermostat.
* If the valve stays open after the thermostat is removed from the water, the thermostat is defective and must be replaced.
* Several types of commercial testers are available. When using such a tester, be sure to follow the manufacturer's instructions.
* Markings on the thermostat normally indicate which end should face toward the radiator. Regardless of the markings, the sensored end must always be installed toward the engine.
* When replacing the thermostat, also replace the gasket that seals the thermostat in place and is positioned between the water outlet casting and the engine block.
* Generally, these gaskets are made of a composition fiber material and are die-cut to match the thermostat opening and mounting bolt configuration of the water outlet.
* Thermostat gaskets generally come with or without an adhesive backing. The adhesive backing of gaskets holds the thermostat securely centered in the mounting flange, leaving both hands of the technician free to align and bolt the thermostat securely in place.
SOURCE: Seat Leon 1.6 - Heater blows cold air & occasional engine o/heat
first check the coolant level and for contamination always check cool or cold fill the resivoir and if it has a rad cap check it too if all looks good then maybe t- stat
SOURCE: 97 Lumina...Switch stuck on defrost vent and
I had same problem . There is a vacuum resovoir tank located behind the left front splash shield . The vacuum line behind the battery goes to it . I removed two 5/32 screws just in front of the tire that hold the splash shield to the fender , carefully flex the shield away from the fender and take a look . I found the vacuum line had come loose , plugged it back on and everything works . Hope this helps
Air
Temperature Control Blend Door Failure No Heat or no AC (dependes on
where door sticks)
In
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.
Other causes of no heat in the cabin are engine thermostats that are stuck open (engine runs cold) or air bubbles in the cooling system.
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