No air in vents or defrost

The blower motor does nothing unless im going over 40mph then heat defrost and ac all work doesn't seem to make a noise when it does work but i can't control how much or how little comes out

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

Experienced mechanics share their insights in answering this question :
Hello. If there is no air coming from your vents then there is likely an issue with the blower motor or circuit. The first thing I would do is check the vehicle’s fuses to make sure that none of them are blown. If any of the fuses related to the AC or blower motor burn out then they can cause the system to not function. If the fuses are okay then it may be possible that the blower motor itself needs to be replaced. The reason the you may be getting air at higher speeds may be because at higher speeds there is airflow that the AC system can use. If the AC is set to allow fresh air into the vehicle, as opposed to cycle the same air, it may be allowing air through the vents when you are traveling at higher speeds. It may also be possible that there is an issue with the AC control unit. This is the component that contains the AC system’s control switches, or even a wiring issue, perhaps related to the control unit or blower motor. I would recommend having a professional technician, such as one from YourMechanic, come to your location to (diagnose the cause of your AC system malfunctions)[https://www.yourmechanic.com/services/ac-is-not-working-inspection].

How to Identify and Fix Common car Problems ?

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

If you can hear the blower motor but no air comes from the vents, check the fresh air intake. If it`s plugged, clean it. If it isn`t, the blend door may be stuck, or the vents may be plugged internally. Check for power at the blower motor.
Here are some of the most common causes of why air doesn`t flow out of your vehicle`s vents: Your air intake is clogged, meaning that air isn`t getting in from the outside at all or isn`t circulating properly. There is a blown fuse in the ventilation system. Electrical issues such as a bad relay.
The most common reasons a Nissan Maxima ac isn`t working are a refrigerant leak, an electrical climate control issue, or a problem with the air conditioning compressor. You may not realize there`s a refrigerant leak until the air conditioner stops blowing cold.
The most common reasons a Nissan Maxima heater isn`t working are a broken heater blower motor, a problem with the thermostat, or a failed heater blower motor resistor. Search our network of RepairPal Certified shops near you to speak with a technician about your issue. Oops! We got lost!
Mode Door Actuators: The mode door actuator controls what vents have air flow, i.e. floor, panel or front, defrost, or any combination of those.
The blower motor is responsible for sending air through the vents of your car. Over time, blower motors can become damaged, or completely fail. In which case, air will no longer come out of your vents.
A dirty air filter can block airflow and reduce cooling to your home. In more extreme cases it can cause the system to shut down completely. If your thermostat checks out and you still don`t have cool air, locate your system`s air filter, turn the system off, remove the filter and inspect.
The most common cause of a vehicle`s air conditioner not getting cold enough is that it needs to be recharged. You can recharge your refrigerant by yourself, but to save time and make sure the job is done correctly you should make an appointment with your local professional auto shop.
If the heater isn`t blowing hot air at you when you turn the system on, the blower fan might have a problem. Either it`s not getting electrical power or, more likely, the motor itself has simply burned out. A blower motor in an older vehicle is likely to burn out over time, and may need replacement.
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.
The defrost relays turn on the compressor, switch the reversing valve of the heat pump, turn on the interior electric heating element, and stop the fan at the outdoor coil from spinning. The unit is now in the defrost cycle.
You may resolve the issue with a simple climate control reset by disconnecting the A/C fuse for about 10 seconds and then putting it back in.
When you turn on the fan, a blower motor sends the air warmed by the heater core into the cabin. To regulate the temperature, small “blend doors” open or close to regulate how much hot or cold air enters the cabin from the heater core or air conditioning unit.
Many vehicles have two fuses for the blower motor, one in the interior fuse block and the other under the hood. The blower motor is usually under the dashboard on the passenger side.
The following problems will cause air duct blockages: Dirt and grime build up in the air duct. Dead animals. Damaged ductwork.
One primary problem for many HVAC systems is that they are not properly cleaned, which can lead to clogged air ducts. Built-up dirt and debris are commonly the culprits of a faulty HVAC system.
If you can hear the compressor running but the fridge isn`t cooling, the problem is most likely either frost-clogged evaporator coils or a stuck or broken evaporator fan. If you hear no sounds and the compressor isn`t running, or you hear a click, inspect the overload relay, start relay, and start capacitor.
If there is the voltage on the “line” side, test for voltage on the “load” side of the fuses by placing the meter`s leads on the load wire lugs. If you read voltage on this side(220-240V), this means the current is flowing through the fuse. If you get a zero-voltage reading on the load, this means your fuse is blown.
Usually, AC units use “TR”-type fuses to ensure safe operation. However, if you need to replace a fuse quickly and don`t have that exact one, you can use a fuse rated for a lower amperage.
Faulty Wiring or Blown Fuses

Similar to your broken HVAC controls, your car`s wiring could be broken or have a short in it. This would mean the heater isn`t triggered when the driver commands it to function.

While this prevents serious trouble such as electrical fires, it also means that a single blown fuse can cause the entire air conditioner to stop working.
Can you top your coolant up with water? Coolant should only be topped up with water in case of an emergency when the coolant liquid level is lower than it should be. While topping up with water will help you get safely to the nearest RAC Approved Garage and identify any issues, it shouldn`t be relied upon.
Your vehicle`s thermostat opens to allow coolant to flow through the radiator and cool the engine down. However, if the thermostat gets stuck in the closed position, the coolant can`t flow through the radiator and can make your engine overheat.
Low Coolant Level

If there isn`t enough coolant in your system, the heater core will blow cold air into your car. Solution: If you confirm that a low coolant level is the source of your problem, you simply need to top off your coolant. You may want to check for leaks as well if you just recently refilled your coolant.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Problem with AC/heater – 2005 Ford Explorer
ANSWER : Hello. The problems you describe with the front system may either be a faulty control switch or faulty vacuum motors for the air blend doors. The problem in the rear is likely the rear heater control valve, which regulates the flow of hot coolant to the rear heater core and air duct system. The clicking noise may be a broken vacuum motor for that valve (integrated in the valve).

I would recommend having a certified mechanic, such as one from YourMechanic, come to your location to perform an inspection of the heater and suggest the needed repairs.

Read Full Q/A … : No air in vents or defrost

air conditioner not blowing air from dash vents, but blowing air from side vents
ANSWER : A few different items can cause the air to not blow out of the dash vents. The most common are a blend door or a control switch. The best method for the AC diagnosis feature can be found in the vehicles owners manual. I recommend having your AC checked by a qualified technician, such as one from YourMechanic, to have the problem diagnosed and repaired correctly.

Read Full Q/A … : No air in vents or defrost

My heater is blowing air through the driver side air vents but is blowing cold air through the passenger side and rear console ven
ANSWER : Hi there:

Climate controlled vehicles have multiple electrical relays that open and close vents to maintain the desired temperature. In some instances, these relays can wear out overtime. However, it’s also common for debris to clog up vents (especially side vents) which may restrict the flow of cool air. The best way to determine why your AC is not working efficiently, it might be best to have a professional mechanic complete a AC inspection; so they can pinpoint the source of your issues and recommend the right repairs.

Read Full Q/A … : No air in vents or defrost

Cold mist/smoke like air comes out of the air vents when cold air is on.
ANSWER : If you are using regular outside air a/c instead of recirculated air you may be getting a large amount of outside air humidity and can cause a mist to come out of the a/c vents. You should make sure the a/c evaporator drain is cleared and drains freely or the water in the a/c cannot drain fast enough and the blower will pick up the water and blow it out the vents.

Read Full Q/A … : No air in vents or defrost

No air coming through any of the vents, defrost, etc.
ANSWER : It sounds like you may have got something stuck in the blower for the A/C. The blower may be blocked or may have burned up. Have the blower removed and tested and checked for a problem. You may have something caught in the motor causing it to lock up. I have seen paper, pens, and even rodents. I know it sounds weird but it happens. It can also just be a blower resistor and blower motor. To have the fault pinpointed in person, a certified mechanic from YourMechanic can take a look at your car to diagnose your AC issue and squealing sound that you are hearing.

Read Full Q/A … : No air in vents or defrost

Air does not come out of the vents very well or at all most of the time. Air does come out of the defrost though.
ANSWER : Hello there, a few different things can cause the air to only blow out of the defrost vents. The car’s HVAC system uses a few doors, such as the blend and mode doors to direct the air through the dash and determine where it comes out and what temperature it is. Given that the air works out of the defrost, the most likely cause would be the mode selection vent. A qualified technician, such as one from YourMechanic, will be able to diagnose your AC issue and perform any repairs required.

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I have a 1999 chevy Tahoe that only blow air from the defrost vents. How can I get the air to blow in your face of feet?
ANSWER : The control actuator that moves the door to control this may have a wiring connector issue due to connections at control head and actuator wiring was miss routed and it pulls the harness connector wires too taught. You should disconnect and reroute the harness to not be too taught and do a drag test and pin connector test to make sure harness connectors are good. You may need to repair one or more connector female pins. If after repairs the actuator may need to be replaced.

Read Full Q/A … : No air in vents or defrost

Having problems with my air conditioner putting out different temperatures from different vents
ANSWER : Hello. Typically when you experience only one side of the system doing this, it is because of a bad air door actuator motor. These are common failures on most cars. If I knew what kind of vehicle this was, I could give you more precise information. When I come across a problem like this, I remove the actuator and see if it is working when the temperature on the dash is adjusted. If it is not, then I replace it. If you need to have this looked at, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose and repair your air conditioning.

Read Full Q/A … : No air in vents or defrost