Q: Strange whirring noise coming from the engine

asked by on August 14, 2016

We recently drove to North Carolina and back, approximately 1400 miles. Before the trip, I replaced the blower motor and resistor under the dash, because the fan would only work on setting 4, and the blower was sounding bad. Everything worked great for about 400 miles, besides the a/c blowing semi cool air. After driving for many hours and stopping for lunch, we continued our journey. Shortly after, mist started coming from the cents and our semi cool air now, had become warm. Not hot, just not cool. I took it as the Freon being low or empty, so we turned the a/c off for the rest of the entire trip. When we returned home, I purchased a bottle with a gauge to recharge the system. I did not use the entire can, but still managed to overfill it. By a little research, I found I could bleed it. I bled very little, and the a/c was working great. After about 3 hours of driving, the warm air returned and a fairly loud whirring sound started in the engine. Sound stops when car is off

My car has 100000 miles.
My car has an automatic transmission.

It sounds like you are getting water built up inside the evaporator housing and need to unplug the A/C drain or you will flood the evaporator, blower motor, and resistor with water and short the motor and resistor again. If you’d like a local expert to check this out, a certified technician from YourMechanic can come to your home or office to inspect the A/C system and whirring noise in order to determine what fixes should be done.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Air not cooling

It is possible that you may have a leak somewhere in the AC system. However it is normal that every few years your air conditioning refrigerant will need to be serviced, as the refrigerant is a gas and does slowly...

Rattling and bumping noises underneath car & getting worse

Hello. Unfortunately, if this is not a mechanical repair to the powertrain it would not be considered under the Lemon Law. Most of the time this noise comes from the exhaust. In a lot of cases, unbolting the exhaust and...

Intermittent overheating

Hey there. This may suggest that the coolant fan relay switch may not be working properly. When you car is moving down the freeway at higher speeds, the engine gets a lot of cooling assistance just simply from the air...

Related articles

How Do Secondary Defoggers Work?
Your Your car is equipped with two defoggers/defrosters. The primary one is in the front, and it’s tied into your air conditioner. Turn the controls to defrost, set your temperature, and then turn on the fan and you can watch...
How Long Does an AC Compressor Belt Last?
For For the air conditioning system in your car to work properly, it has to pressurize refrigerant. That is the function of the AC compressor. The compressor itself gets a signal from the AC relay, and is operated by a...
How Long Does an AC Compressor Relay Last?
Your Your car’s air conditioning system needs to be able to pressurize refrigerant in order to operate. The AC compressor relay is an electronic component that turns your AC compressor off and on. Without it, the compressor will not work,...