Q: My 2008 Honda Accord blows hot air and the ac make Lois humming noise

asked by on May 09, 2017

We just bought a 2008 Honda Accord about a month ago. We noticed that when the ac is on, the car has a loud humming noise. Once you turn off the ac the sound stops. Last week, our ac started blowing hot air. We bought a DIY ac recharger but it wouldn't in take any of the product, the vavle stayed on the red area.

My car has 137000 miles.
My car has an automatic transmission.

To determine the exact fault, the system will have to be tested. You can obtain that service by requesting an a/c system diagnostic. If the a/c switch was set to "on" and you attached a can of refrigerant with an integral color-coded gauge, the reason the gauge displayed in the red (overcharged) zone is the compressor was not on (that’s an indication of the fault by the way; for some as yet undetermined reason your compressor is not coming on). What happens when the compressor is NOT on, is the LOW side pressure is actually way, way above that expected during normal re-charging. So, when you attach that gauge to a non functioning system the gauge necessarily reports the pressure as "off-scale" high (red). A functioning system has a LOW side pressure of roughly 35 PSI (high side could be in the neighborhood of 200 PSI) while, again, when the system is off, or not functional, low side pressure rises to a static value of roughly 70 PSI.


At any rate, the experience you are reporting with the recharge can suggests your compressor is not turning on. The noise you are reporting could be caused by faults in a lot of different a/c related components: the condenser fan, the passenger compartment blower, the compressor clutch, or the compressor itself. Your system has at least a partial charge so what the mechanic will likely do initially is turn the compressor by hand (with the car OFF) to see if it is seized. If it is not seized, and yet when the A/C switch is in the on position, there is no power to the clutch, that circuit has to be diagnosed. On the other hand, if there is power to the clutch, but no clutch operation (the a/c clutch mates the compressor itself to the drive pulley), then you need a new clutch. There are other checks that will be performed, if necessary, but the bottom line is if you request the diagnostic, the mechanic will pinpoint the fault for you and get this resolved. It is probably a reasonably circumscribed fault. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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

Water dripping on my feet and the passenger side 2011 Honda Pilot

Hello. If the vehicle has a sun roof then it more than likely has a clogged drain. If there is a clog then the water will enter the vehicle. If it does not then there may be a problem within...

A clicking noise coming from the engine bay, gets louder when you give it gas.

With the description that you have given above, it sounds like you may be describing an exhaust leak. The tick could be the exhaust gas escaping from a small crack, or where a gasket has been compromised, and this is...

Parking lights are not working - 2009 Chevrolet Impala

The park, tail, license and marker lamps are turned on when the headlamp switch is turned on, or anytime the automatic light control turns the headlamps on. In either of these scenarios, the body control module (BCM) applies ground to...

Related articles

What Sensors in the AC Tell the Car If the System Is Working or Not?
The The average car today contains a bewildering range of sensors that feed information to various computers to monitor everything from air intake to emissions and engine timing. Your car’s air conditioning system also contains a couple of sensors that...
A Buyer’s Guide to the 2012 Honda CR-Z
In In the tradition of the sporty CRX, the CR-Z boasts some of the similar look, without quite the same amount of pep. That’s because the CR-Z is Honda’s eco-friendly offering and a pretty unique one to boot – (as...
Symptoms of a Bad or Failing Refrigerant Pressure Switch (Sensor)
Common signs include the AC working intermittently or not at all, noise coming from the system, or warm air blowing from the vents.