Car will blow cold air but will not blow heat

ANSWER : Hi there. Based on your question and input, it looks like your AC control switches are damaged, causing the vents to activate even if the switch is not activated. This is sometimes an electrical problem, as it could be triggered by a damaged electrical relay. You might want to have a professional mechanic complete an AC is not working inspection, so they can determine what is causing this issue you’re experiencing and recommend the right repair.

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.

ANSWER : The heater and the air conditioner both use the same blower motor. However, Nissan does have two separate fuses for the same unit. One of them can be blown. There are also resistors in the system that can fail. There are several electrical tests that can be done, but depending on the condition, it may be more practice to change the entire unit. Due to the age of your vehicle, and the Juke’s history of blower motor issues, it’s very likely a simple fuse issue. These can (for the most part) be visually inspected, and are cheap.

ANSWER : When the car is moving, versus stopped, there is more air flow over the condenser (the heat exchanger in front of the radiator) and that airflow is essential to system operation. To maintain airflow when the car is in stop and go traffic, or is completely stopped, condenser fans will come on automatically. If the fans don’t come on, the circumstance you have could occur. You might also have a low state of refrigerant charge. Other possibilities are that the compressor clutch is not cycling as intended or that the condenser might be blocked or dirty. And, of course, you could have a combination of these issues. To get this resolved, the best thing to do is request an air conditioning system inspection. The responding certified mechanic will come to your location, pinpoint the fault and get this resolved for you. Once diagnosed, the mechanic will be in a position to give you a repair strategy to get the A/C system fully functioning and he or she will estimate the cost of the required repair. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

ANSWER : It sounds like you have failed cooling fans. When the car is at idle, the fans should run to pull air across the A/C condenser to regulate refrigerant temperatures and the radiator to regulate coolant temperature. If these fans fail, then these components will receive no airflow at idle, but will still get airflow while driving due to the car moving. I would suggest having a qualified technician, such as one from YourMechanic, inspect your fan operation, as well as the rest of the cooling system for proper operation.

ANSWER : First, the coolant level should be checked to make sure the radiator is full. While the overflow tank may be full, the radiator cap must be taken off to check the level inside the radiator. If you find the level is very low, you have a coolant leak that must be fixed. If coolant levels are normal, an engine thermostat or heater control problem may be what you’re experiencing. Consider hiring an experienced technician like one from YourMechanic who can come out and take a closer look at your lack of heat concern to offer a more personal diagnosis.

ANSWER : Hello. With the recent repairs that have been made to the vehicle, there is only one main heating component that you have not looked into. This would be your heater core. The heater core is responsible for pulling hot coolant from the engine. This hot coolant runs through the heater core as the ambient air is pushed through to warm before entering the cabin. If the coolant can’t flow through the heater core, then the air will blow cold. This can be caused by a clog, a faulty switch, or a process known as electrolysis (electrical current running through coolant). Unless there is a clog that can be dislodged, these issues will all result in a new heater core. To get a precise diagnosis of the problem, I recommend having an expert inspect the overheating problem so this can be resolved.

ANSWER : If the A/C system is full and pressures are reading correctly, and the cooling system is in proper working order (thermostat opens, no overheating, etc.), then most likely the problem lies with the dash. The climate control head unit may be at fault. One or more blend doors behind the dash may be stuck or broken. If you’re unable to fix this issue yourself, consider YourMechanic, as one of our mobile technician can come diagnose the issue with your A/C firsthand and help you fix it accordingly.