Car will overheat if I don’t have the fan on. When fan is off it doesn’t come on to release heat from engine. So the fan is always on.

ANSWER : Check the wiring to the coolant temperature sensor and see if there is power to the sensor switch. If there is no power, then check the cooling fan relay and see if its clicking on. If there is no clicking motion, then remove the relay and check for power to the relay. If there is power to the relay, then the cooling fan relay needs replaced. If there is no power to the relay, then check the fuse. If the fuse is burned, replace the fuse. If the fuse is good, then check power from the fuse to the main circuit on the fuse box. If there is no power, then the fuse box needs replaced. If the fan comes on with the air conditioning system switch turned on, that is because the switch overrides the cooling switch to make the condenser cool down to make the air conditioning system work properly.

If you need further assistance with your cooling fans not coming on when the engine gets hot, then seek out a professional, such as one from Your Mechanic, to help you.

ANSWER : The control circuit for the fans needs to be checked. For example, there is usually a condenser fan relay in the A/C electrical controls. There could be a fault with that relay and/or wiring problems, perhaps even just a loose connection, blown or loose fuse, and so forth. To resolve something like this, the recommended service is an electrical component diagnostic. If you request that diagnostic service, the responding certified mechanic will get the problem pinpointed and resolved. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

ANSWER : The first thing is to make sure the cooling system is indeed full. When the heat turns cold, this could be an electric problem or there could be an air bubble in the cooling system. A low cooling system can also affect the fan operation. The best method for checking the cooling system level is to remove the radiator cap first thing in the morning before you start the car. If coolant isn’t showing just under the radiator cap, top it off and make sure the coolant overflow container is filled to the appropriate mark.

If the cooling system is full, and the fan still turns off after five seconds, the cooling fan circuit will need to be diagnosed. With a symptom such as yours, it indicates there is a bad connection in one of the components of the cooling fan circuit. It is very common for electrical circuits to develop weak spots that fail shortly after they are turned on. Heat will build at the bad connection and stop electricity to flow. When the circuit is allowed to cool, it will again operate for a short time.

Possible component failures include the radiator fan, radiator fan relay, radiator fan switch, a bad connection at a connector and a fuse with a bad connection. The best spot to begin diagnosing the cooling fan is to pull the radiator fan relay and use a test light to check that the proper circuits are supplying power as well as use a jumper wire to supply power and or ground to the cooling fan to test the fan operation. Testing of this sort requires a wiring diagram, a test light and an understanding of electrical theory.

If you should require assistance with this, I would recommend having your car’s overheating issue inspected at your home by one of our mobile technicians.

Good luck!

ANSWER : There are a couple of possibilities for such a rapid overheating situation. The thermostat may have failed in the "closed" position preventing the hot water from circulating and cooling in the radiator. The water pump or the serpentine drive belt may have failed and the hot water does not get circulated through the radiator.

If one of the head gaskets on the engine has failed, combustion gasses from one or more cylinders can "superheat" engine coolant very quickly. If the coolant level is low and there are air pockets in the engine, the coolant is literally "boiled away" inside the engine, creating far higher temperatures than an engine that is "full of coolant".

It is recommended that you get a mobile, professional mechanic, such as one from YourMechanic, to perform an inspection and determine the cause of the overheating.

ANSWER : Hi There,
It sounds like you may have a dirty or faulty mass air flow sensor. The problem this can cause may also be compounded when the engine is cold due to the change in air density in cooler weather. The mass air flow sensor monitors air intake as it is mixed with fuel prior to being injected into the motor. This sensor relays information about fuel and air temperature, air speed entering the motor and many other things to the ECM which uses this to make adjustments to fuel supply to the motor. A dirty or faulty sensor can cause an imbalanced air/fuel load to be supplied to the motor which results in an over fueling or under fueling situation depending on the conditions. This type of inconsistent fuel supply to the motor may cause a hesitation, loss of power, a jerking reaction, potentially a bit of black exhaust smoke and typically a strong smell of fuel when this sensor is malfunctioning. I would suggest having a professional from Your Mechanic come to your home to diagnose and inspect your vehicle.

ANSWER : You will need to have the cooling fan system checked to see if the fans come on without the a/c being on to see if the engine computer [(ECM) is activating the low speed or high speed fan relays. The ECM uses the engine coolant sensor as an input when to turn on the two relays. The ECM will need to be scanned and data monitored to see if relays are turned on by ECM but not turning on fans. The relays may be defective.

ANSWER : Hi there. Typically the fan, AC system and other components on your Honda is driven by the same belt, called a serpentine belt. When the belt brakes frequently, it’s typically due to the pulley’s that drive the belt being worn out, misaligned or not properly adjusted. Before you take your car to the same mechanic to attempt this repair again, I would highly recommend having one of our professional mechanics complete an inspection at your location to determine what needs to be fixed on your Honda.

ANSWER : It sounds like you’ve taken all the right steps, so I understand if you are frustrated. If you look in the fusebox again, you might find a fusible link that powers the fan if you haven’t already checked that. Most late model cars activate the fan via the ECU which activates the relay, so you are at a point where diagnosis may require a scan tool that has the ability to do activation. You can have that checked right there on the spot by contacting Your Mechanic. They can send a technician to your home or office to check out your cooling fan and let you know what it will take to solve your problem.