The blower motor resistor is prone to shorts, corrosion, and overheating. When the resistor fails, typically, the highest setting is the only option that still functions. This is because the air from the blower motor is bypassing the resistor, thus gaining the maximum amount of voltage, resulting in full power.
If your air conditioner works on high, it is a very specific issue. It can mean that there is a problem with the blower motor, the control board, or the thermostat. However, we still do a full diagnostic check-up to ensure that all of the switches, wiring, and fuses could not be causing the same issue.
Airflow Over the Condenser: The AC system relies on airflow to help cool the refrigerant. When the car is moving quickly, more air flows through the condenser, allowing it to dissipate heat more effectively. At lower speeds, the airflow is reduced, which can cause the AC to struggle to cool the air.
If the vehicle's voltage is low, the AC compressor will not be turned on. This could indicate an issue with your battery or alternator - the alternator generates more power when spinning faster, so perhaps the voltage only rises above the minimum on high rpm or acceleration.
The average cost for a Blower Motor Resistor Replacement is between $119 and $154. Labor costs are estimated between $43 and $54 while parts are priced between $76 and $99.
Should I drive if my blower motor resistor is broken? You can drive, of course, but you might not be able to regulate the fan speeds in your car, which could interfere with both comfort and defrosting power.
If the refrigerant levels in the AC system are low, the system will not be able to cool properly. Clogged condenser or evaporator coils. If the condenser or evaporator coils are clogged, the system will not be able to cool properly, especially noticeable when the car is idle.
Some increase is normal because the A/C compressor needs engine power to run. Unless it's affecting the cars ability to drive, I wouldn't worry about it. If it gets worse, it could be your IAC (idle air controle valve) or a fast idle solenoid.
It happens because the air passes through the condenser when the vehicle is accelerating. So even without the fan, the air still flows through the condenser coils. That explains why the A/C vents don't release cool air when the vehicle is stationary.
What are some symptoms of a failing AC compressor? Loud noises, hot air, airflow issues, uneven cooling, and electrical problems are all things you might run into when an AC compressor is on its last leg.
Defected condenser fans can be among the major causes when air conditioning only works when driving. Condenser fans help reduce the refrigerant's temperature to ensure it condenses. Malfunctions in condenser fans can prevent this from happening.
When a resistor fails, the fan will often run only at higher speeds or the highest speed, no matter what fan speed is selected. In some vehicles, though, the fan may not work at all, and only a little may come through the vents.
Replacing a furnace blower motor costs $560, on average. Depending on the size and type of motor, most people pay $300 to $900. The average blower motor replacement cost is $560, but the final price depends on labor fees, as well as the cost of the parts.
On average, AC compressor costs range from $800 to $2,300, with most folks paying $1,200 for a new one. However, your price will vary depending on factors like the size and brand of your compressor. Before you schedule your replacement, read on to learn about all AC compressor cost factors.
Clean or Replace the IACV: A dirty Idle Air Control Valve is a common cause of fluctuating RPMs. Cleaning or replacing it can help stabilize your engine's idle. Get Your Sensors Checked: If you suspect a sensor malfunction, have your car diagnosed by a professional to identify and replace the faulty component.
We can see that the angular velocity, AKA electric motor speed, AKA RPM, is proportional to voltage and negatively proportional to torque. Therefore, if we want to increase the motor's speed we can either a) increase the voltage delivered or b) decrease the torque.
Common Reasons AC Doesn't Run Cold
The most common causes of broken air conditioning leaks or compression issues. If you are feeling cool — but not cold — air, the issue could be a clogged filter, a problem with the cooling fan, signs of radiator trouble, or it could simply mean it's time to recharge your AC.
A very useful diagnostic aid is the “Feel Test”. As the test implies it is a matter of quite simply feeling tubes and components for temperature drops, indicating possible blockage location. By this stage you would be aware of what side of the A/C system should be hot and what side should be cold.
Thus, when the fan becomes defective, it creates various complications in the air conditioning unit. This causes lukewarm air, burning smell, overheating when idle.
Blower Motor Resistor Test
Typically, if the fan will work on some speeds but not on others, the resistor is suspect. Okay, let's say there's no melting going on, but your fan doesn't work on all speeds. Typically, if the fan will work on some speeds but not on others, the resistor is suspect.
In general, the parts themselves usually cost between $20 and $100. Labor costs for installation range from $50 to $200, depending on the complexity of the installation and the mechanic's labor rate. Therefore, the total cost can range from $70 to $300.