Overheating issue, when heater is on its normal temp. but if heater is off it begins to overheats, until heater is turn on again.

Overheating issue, when heater is on its normal temp. but if heater is off it begins to overheats, until heater is turn on again.

When driving, car over heats, but if I turn heater on, temperature eases back to normal, and is good to go unless I turn heat off again. Even when in idle doesn't run hot with heater on, but if heater is off it over heats.I put new water pump thermostat radiator degas bottle and cap heater control valve and bled it several times

My car has 200000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :

It sounds like your engine might have a restriction in the cooling system. If the cooling system has a restriction that prevents its flow, this will cause the engine to get hot. The heat is dissipated from the cooling system by means of the radiator.

When a restriction exists sometimes the radiator alone is not enough. The heater core is like a small radiator inside the dash and is also another means of dissipating the heat from the cooling system. So essentially when the heat is on you are introducing a second radiator into the system which will help to cool the engine down.

In order to get this fixed, consider YourMechanic, as one of our mobile technicians can come to your home or office to diagnose the overheating issue firsthand and help you make the necessary repairs.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

It sounds like your engine might have a restriction in the cooling system. If the cooling system has a restriction that prevents its flow, this will cause the engine to get hot. The heat is dissipated from the cooling system by means of the radiator. When a restriction exists sometimes the radiator alone is not enough.

If your car begins to overheat when idling, but the temperature gauge moves back down once you get going, it`s most likely due to a broken radiator fan. When the coolant goes to the radiator, it`s spread over a large surface area to cool it down. Airflow further cools it before it returns to the engine.

It`s probably because the heater is plugged with dirt or debris. When it gets plugged or clogged, the coolant flow is restricted, causing your engine to overheat. Besides, your cooling system may not be working properly due to issues like low coolant levels, a broken fan, or a clogged-up radiator.

The most common reasons a Lincoln LS is overheating are a coolant leak (water pump, radiator, hose etc.), the radiator fan, or a failed thermostat. Coolant leak (water pump, radiator, hose etc.)

It sounds counterintuitive, but Reina recommends turning on the heater. It draws warmth away from the engine and into the passenger compartment, lessening the burden on the engine`s cooling system. In certain circumstances, that may be enough to reverse the overheating, he says.

Car overheats when driving but not when idling

If your temperature gauge is fine until you make the car work, the most likely issue is coolant flow.

Pull over and shut off the car. Allow the engine to cool for at least 15 minutes. Keep an eye on the temperature gauge, as it should move back to a normal range as the engine cools. While you`re waiting (and watching the gauge), put together a plan to get your overheated engine checked out.

Radiators are comprised of long tubes through which coolant circulates. The primary cause of an overheating radiator is debris and sediment building up inside the tubes and causing a blockage. This then means that coolant cannot pass through, causing the radiator and subsequently the engine to overheat.

Your car is overheating.

Lastly, a sure sign of a bad heater core is when your vehicle overheats. This could be due to a blown head gasket or a plugged heater core issue. Do not drive your vehicle if it continues to overheat, and make sure to bring it in to your local automotive repair shop as soon as possible!

If your coolant level is a-okay, but your car heater is blowing cold air and your engine is overheating, then you have a clog in your cooling system. Conversely, if your engine temperatures are unrealistically low after a drive, your thermostat is likely the culprit.

Leaks are the #1 reason a vehicle begins to overheat. Leaks in hoses, the radiator, water pump, thermostat housing, heater core, head gasket, freeze plugs and a few other things can all lead to problems with the vehicle`s cooling system.

Unlike first-generation OE electronically managed engines that didn`t go into “closed-loop” until coolant temps hit 195 degrees F, Rollings says GM LS engines typically go closed-loop around 160 degrees.

COOLANT TEMPERATURE SENSOR FAULTY: SYMPTOMS

Higher idle speed. Increased fuel consumption. Poor starting behaviour.

Radiator Hose Troubles:

Another symptom of a clogged or faulty radiator is if the radiator hoses are hot to touch. The hoses carry the car coolant from the radiator to the engine. If the hoses are hot, it means that the coolant is not flowing correctly and the engine is overheating.

If your coolant reservoir is boiling but your engine doesn`t overheat, then your coolant may not actually be too hot. Those bubbles you noticed are more likely air bubbles that found their way into the coolant reservoir—not from the piping hot coolant. In most cases, the issue is actually a leak in the radiator cap.

While a lack of interior heat from a bad heater control valve is a serious enough problem, the real danger from a bad heater control valve is the possibility that enough coolant could leak out to cause your engine to overheat.

Many issues with a heater control valve can stem from a coolant leak, which can cause your engine to overheat – posing a serious risk of expensive engine damage. It is important to get your vehicle inspected by a car care professional right away if you notice any of the above signs.

Can a bad heater core cause overheating? Yes, a leaking heater core can cause a loss of coolant and subsequent engine overheating. Although not as common, it`s also possible for a heater core to become obstructed enough to restrict coolant flow and cause overheating.

Causes of this can be not having enough coolant, a broken thermostat, a damaged heater core bypass valve, or a blockage in the core itself. If you encounter any of these issues, you should never drive an overheating car. Have it towed to an auto shop if you must, but you never want to risk your car`s engine.

Turn on the heat to cool the engine.

Turning on the heat might be the last thing you want to do on a hot summer day, but it can pull hot air from the engine compartment and cool the engine.

Also called heat illnesses, there are several forms of hyperthermia. Heat cramps are fairly mild, whereas heat exhaustion is more severe. Heatstroke is the most serious form of hyperthermia and can be life-threatening.

If you notice that your engine overheats, the coolant temperature sensor could be the problem. At times, the coolant temperature switch may fail such that it starts transmitting hot signals permanently. This causes the computer to erroneously counterbalance the signal, thereby causing the engine to misfire or overheat.

It gets even more concerning and confusing when car overheating suddenly returns to normal. This phenomenon can happen for many reasons, like a bad thermostat, a faulty radiator, or a coolant leak. As such, it`s best to get your car checked by a professional— like RepairSmith!

So what`s a normal temperature for your vehicle`s engine? Most experts agree that your engine should run between 195 degrees and 220 degrees. In ideal situations, your needle will maintain a posture right in the middle of your gauge.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Overheating issue, when heater is on its normal temp. but if heater is off it begins to overheats, until heater is turn on again.

ANSWER : It sounds like your engine might have a restriction in the cooling system. If the cooling system has a restriction that prevents its flow, this will cause the engine to get hot. The heat is dissipated from the cooling system by means of the radiator.

Read Full Q/A … : Overheating issue, when heater is on its normal temp. but if heater is off it begins to overheats, until heater is turn on again.

Overheats when heater is on, heater blows cold air.

ANSWER : Since you had cooling system work done recently, one possibility is the cooling system is air bound. If air is trapped within the cooling system and not properly bled from the system after a repair, the air can cause the coolant to not circulate properly. This can lead to overheating and no hot air from the heater. Another cause that can simply be coincidence is a stuck thermostat. The function of the thermostat is to allow the engine to reach a certain temperature before opening and allowing coolant to flow throughout the cooling system. If the thermostat is stuck closed and fails to open, the coolant will not flow properly and cause the engine to overheat. The heater will blow cold air because hot coolant is not flowing to the heater core behind the dashboard to provide heat for the interior. Have a certified technician diagnose the engine overheating as soon as possible. Continued driving while overheating can damage the engine.

Read Full Q/A … : Overheating issue, when heater is on its normal temp. but if heater is off it begins to overheats, until heater is turn on again.

Just replaced head gasket, changed crack sensor new plugs. The check engine light is on, but dim, the only other light that the dash is a normal battery indicator. The fuel pump is not running when switch is turned on, the power windows don’t work, it turns over but not firing. It’s like only one part of the system is working. Also the heater fans work even if the switch is off.

ANSWER : I would first look at the diagnostic trouble codes. Those codes are available because the check engine light is on. If the fuel pump is not running (momentarily) at key on, that fault alone will prevent the car from starting as there will be no fuel pressure. Pump output and pressure can be directly tested and you can also check for electrical power to the pump. To find out why the engine will not run, the recommended diagnostic is a no start diagnostic. If you request that service, the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

Read Full Q/A … : Overheating issue, when heater is on its normal temp. but if heater is off it begins to overheats, until heater is turn on again.

Engine turned off but inside of car still on, now engine won’t turn back on.

ANSWER : Hi there. The symptoms you’re describing with your boyfriend’s 2002 Grand Cherokee appear to be related to a broken or worn out ignition switch or relay. The ignition switch on the inside of the steering column is attached to multiple electronic connections that send signals to a relay box; which in turn, sends the signal to the individual components. The issue could be related to the ignition switch, the relay, or any of the components in between. If you want to have the fault pinpointed in person, I would have this starting issue inspected by a trained professional to ensure that the correct repair is made.

Read Full Q/A … : Overheating issue, when heater is on its normal temp. but if heater is off it begins to overheats, until heater is turn on again.

My cooling fan won’t turn on when I turn the ac on. Relays and fuses are good, tested the fan with the battery and it came on??

ANSWER : Hi there. In general, a situation like this occurs when either the thermostat housing or temperature sensor is not relaying the information to the fan motor to activate. However, it’s also possible that there is some electrical short within the cooling system relay’s that is causing the fan motor to not activate when it should. I think the best way to determine the precise source of this problem is to have a professional mechanic come to your location to complete an onsite inspection so they can test all systems to help isolate the root problem and recommend the right repairs.

Read Full Q/A … : Overheating issue, when heater is on its normal temp. but if heater is off it begins to overheats, until heater is turn on again.

When I turn ON the Heater The Radiator Fan turns ON too and make the car engine cold could you please tell me the solution the fan

ANSWER : Hi there. Is the climate control set to defrost on the windshield? If so, this still engages the ac compressor and turns the radiator fans on. What is the current coolant level? A slow coolant leak may leave a trail of dried coolant, but the level may not be enough to cause overheating at the moment. If the coolant level is low this will affect the operating temperature of the engine and heater as well. A low coolant level can affect your air condition when the weather warms up; having a coolant concern corrected before summer can avoid possible air conditioner concerns. I suggest having a qualified technician perform an inspection to avoid replacing unnecessary parts. Your Mechanic has several available technicians that can assist you with a heater does not work inspection.

Read Full Q/A … : Overheating issue, when heater is on its normal temp. but if heater is off it begins to overheats, until heater is turn on again.

Heater was not blowing warm air and then the engine overheated.

ANSWER : The heater not working in some cases may be related to the overheating problem you are also having. This may be due to a faulty heater blower motor or potentially a bad heater core. As you may know, the heater core is a small radiator like unit that circulates the hot coolant from the engine through the heater core which then uses this warm coolant to heat the inside of the car with the help of the blower motor that blows the warm air through the vents inside the car. When the cooling system is not properly circulating coolant through the motor, this results in the warm coolant not being pumped through the heater core properly in order to warm the inside of the vehicle.

Engine overheating can be caused by a number of things such as low coolant levels, a faulty thermostat, or a failing coolant fan switch. As you may know the coolant fan switch helps to maintain the proper coolant temperature by turning on and off at specific temperature thresholds. When this switch is not working properly, this can cause the fans to come on intermittently, all the time or sometimes not at all. When this happens you will notice a temperature spike and drop occasionally as the fan comes on and off. When your thermostat is not working properly or is stuck closed, this will not allow the coolant to properly circulate through the engine, which may cause the engine temperature to fluctuate erratically or in some cases just remain hot. As mentioned above, this also restricts the warm coolant from flowing through the heater core which uses this to blow warm air into the cab of the vehicle. I would suggest having an expert from Your Mechanic come to your home to diagnose your cooling system.

Read Full Q/A … : Overheating issue, when heater is on its normal temp. but if heater is off it begins to overheats, until heater is turn on again.

My car starts to overheat in stop and go traffic until I turn on the heater. It then goes back to normal.

ANSWER : You may have a leak you have not seen if you had to add coolant. You should also not have to turn on the heater to full blast to cool the engine. This tells me you either have a cooling fan that is not working or a radiator that is clogged. I would suggest having a mechanic, such as one from YourMechanic, come to you to diagnose the overheating issue by first pressure testing it for leaks and then checking coolant quality and radiator for proper flow and fan operation.

Read Full Q/A … : Overheating issue, when heater is on its normal temp. but if heater is off it begins to overheats, until heater is turn on again.