Why does my AC only work when the fan is on?

When the ac compressor not working but the fan is running, chances are the outer unit housing the compressor isn’t receiving power. The fan keeps running because the central unit has no such problem. Other potential causes may include a faulty thermostat, mismatched indoor and outdoor units, or the AC may just be old.

Why does my AC not work at high speeds?

The A/C thermal expansion valve (TXV) most likely is the cause of the A/C system freezing up at higher engine or vehicle speeds. The A/C system should be performance tested and checked for pressures to make sure the system has enough refrigerant or the TXV is the cause of the problems.

What controls the speed of the AC in a car?

The speeds are controlled by a resistor or a computer control module activated by the blower fan switch. When the AC fan is not working it’s usually caused by some sort of fault in the blower motor or resistor.

Does engine cooling fan affect AC?

A lousy radiator fan can create car air-condition (AC) issues. This is because the radiator cooling fan creates double the amount of air that the condenser fan. The radiator fan pulls air through the condenser, which removes the heat vapor of the refrigerant inside.

Why does my car AC only work while driving?

This is because it is not able to regulate the refrigerant needed to cool down the air. You may notice the car being most affected when stopped, as the engine is not working as hard, and there is no airflow from driving down the highway.

Why does AC only work when car is moving?

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. Other possibilities are that the compressor clutch is not cycling as intended or that the condenser might be blocked or dirty.

Why does car air conditioner stop working after a few minutes?

There are several possible causes of a vehicle’s air conditioning system to stop working after being on for only a few minutes. Basically the causes are either the A/C evaporator is getting too cold and icing up or there’s an electrical problem causing an open circuit.

Why does my car AC fan only work on high?

When a blower resistor fails, the highest fan speed usually is the only one that still works because it essentially bypasses the resistor and receives the maximum amount of voltage. When the resistor is working, it reduces the amount of voltage going to the lower fan speeds, so the fan runs slower.

How do I know if my cooling fan relay is bad?

Bad Cooling Fan Relay Symptoms

1. The engine runs hot or overheats.
2. The cooling fans don’t work.
3. The cooling fans keep running.
4. Warning lights.
5. Poor air conditioning performance.
6. Swapping Relays.
7. Measuring the Relay Coil’s Resistance.
8. Listening for Noises.

What are the symptoms of a bad AC relay?

Signs of a Bad or Failing AC Compressor Relay

• Inconsistent cooling. The AC compressor is powered by the relay.
• AC compressor is not turning on. One of the most obvious signs that the AC relay may have a problem is that the compressor is not coming on at all.
• No cold air.

Why does my air conditioner only run at one speed?

Though having only one fan speed usually indicates a bad blower resistor, a diligent mechanic at a repair shop will test the resistor, fan switch and connections to the motor to make sure nothing else is wrong before they start replacing parts.

Why is my air conditioner fan not blowing hard?

Odds are good that the fan switch may be at fault, but a more likely reason is that a blower motor resistor that controls the voltage going to the blower has packed it in, resulting in only one speed remaining operable — usually the highest speed, which you may not always need depending on the temp of the outside air.

Can a resistor card cause AC to run at low speed?

The blower fan should be mounted behind the glove box and there’s a resistor card lurking in same box as blower fan. The resistors drop +12 volts to different levels to create blower speeds. In theory the resistor card could not cause the AC to run just on low-speed.

Can a blower motor resistor cause a heater fan to stop working?

In some cars, a failed blower motor resistor can cause a heater fan to stop working completely. In most cases, a blower motor resistor fails due to corrosion or overheating. Sometimes, the mechanical resistance to the motor rotation causes an excessive electric current that can overheat and prematurely damage the blower motor resistor.