dtorres Posted November 2, 2012 Report Share Posted November 2, 2012 Has anyone noticed a weird and loud fan noise from the engine compartment on startup after the vehicle has been sitting for a while. I've noticed it in the morning and after work after the vehicle has been off for quite awhile. There's a noise that can best be described as a computer case fan going bad. As if there's a fan with bad bearings. I've also noticed if I hit the A/C button so it reads A/C off the noise goes away. Hit the button again (A/C reads on) and the noise is back. Goes away after about 5 minutes of driving and doesn't occur if the vehicle was recently driven and is already warmed up. Ubernuts 1 Quote Link to comment Share on other sites More sharing options...
C-MaxJaxon Posted November 2, 2012 Report Share Posted November 2, 2012 I've heard it before. I assumed it was the electric A/C. I think I've heard the same buzz briefly a couple times on startup even with the A/C off. Quote Link to comment Share on other sites More sharing options...
CNCGeek Posted November 2, 2012 Report Share Posted November 2, 2012 I hear this often and even when I unlock the doors, I had thought maybe it was a pump for the power steering or brakes getting those systems up to pressure before the car was ready to drive (so there would be no lag between starting and driving). I have a wild imagination though. Quote Link to comment Share on other sites More sharing options...
dtorres Posted November 2, 2012 Author Report Share Posted November 2, 2012 O.k., it sounds like it's normal than so no need to waste a trip to the dealership. Quote Link to comment Share on other sites More sharing options...
CNCGeek Posted November 3, 2012 Report Share Posted November 3, 2012 I was pulling out of the garage today and a friend who was outside said it sounded like I had a little electric chainsaw running under the hood for about a minute. Whatever pump they use, it is loud (I am assuming it is a pump). Seems like they could have done a better job with that. Quote Link to comment Share on other sites More sharing options...
dtorres Posted November 3, 2012 Author Report Share Posted November 3, 2012 I was pulling out of the garage today and a friend who was outside said it sounded like I had a little electric chainsaw running under the hood for about a minute. Whatever pump they use, it is loud (I am assuming it is a pump). Seems like they could have done a better job with that. That's the noise I'm talking about! If you open a door there's a separate buzz noise but it's short less than 10 seconds. It's the electric chainsaw buzzing noise after starting the car. Funny thing is I never noticed it either until my wife used the car and was backing out of the garage while I was nearby. Next time I used the car I rolled down the window and could hear it. Next cold start try rolling down the window and after it starts press the A/C button until it reads A/C off and it goes away. Ubernuts 1 Quote Link to comment Share on other sites More sharing options...
rfruth Posted November 3, 2012 Report Share Posted November 3, 2012 I think the noise is the the radiator fan (the air it moves) - all cars make this noise but its hard to hear with the gas motor running (the fan cycles on & off as needed) Quote Link to comment Share on other sites More sharing options...
dtorres Posted November 3, 2012 Author Report Share Posted November 3, 2012 I think the noise is the the radiator fan (the air it moves) - all cars make this noise but its hard to hear with the gas motor running (the fan cycles on & off as needed) I suspect you're right that it's some kind of fan or pump and that normally you'd never hear it because of a gas motor. I'm just curious why it's linked to turning the A/C on and off. This morning I didn't hear it and noticed that I had left the A/C turned off last night (the climate control system was set to Auto and there was still air blowing through the vents). I hit the A/C button and the buzzing noise immediately started. Hit the A/C button and noise went away. It's not that big of a deal, I was just curious if it was normal. On a regular car I'd assume the sound was a bad A/C compressor or compressor pully. But on this car there are no pulleys or belts only electrically controlled pumps and compressors. rfruth 1 Quote Link to comment Share on other sites More sharing options...
rfruth Posted November 8, 2012 Report Share Posted November 8, 2012 Most cars turn on the radiator fan when the A/C is turned on (if the fan wasn't on anyway) this helps with engine cooling, not sure how useful this is with the C-Max since it has a electric A/C though :headscratch: Quote Link to comment Share on other sites More sharing options...
Antone Posted November 8, 2012 Report Share Posted November 8, 2012 My guess is that sensors detect refrigerant gas pressure in the evaporator section of the a/c, the pump turns on to re-liquify the gas and store it in the receiver. Once the gas pressure is low enough, the pump turns off. If cooling is required this pump should cycle or run continuously. Quote Link to comment Share on other sites More sharing options...
dtorres Posted December 7, 2012 Author Report Share Posted December 7, 2012 I took my car to the dealer to have a warped door seal fixed and I mentioned the chain saw like buzzing noise at start up if the A/C is on. After comparing it to another C-Max on the lot they determined that it was "significantly louder" then the one on the lot when the A/C was switched on. They said they're contacting Ford to determine if Ford considers this acceptable or if they need to replace the electric A/C compressor/clutch. Fingers crossed for replacement of the part. Ubernuts 1 Quote Link to comment Share on other sites More sharing options...
dtorres Posted December 22, 2012 Author Report Share Posted December 22, 2012 I forgot to post back that Ford's final answer to the dealership was that the noise is normal for the C-Max at start up with the A/C on, do not replace the part. The service lady gave an explanation from Ford that was similar to what Antone posted above. Quote Link to comment Share on other sites More sharing options...
Arthur Posted January 9, 2013 Report Share Posted January 9, 2013 Mine makes the noise with the A/C OFF, it may be a fuel pump building pressure. I have two other engines that do that. Quote Link to comment Share on other sites More sharing options...
valkraider Posted January 10, 2013 Report Share Posted January 10, 2013 Even with the AC off the compressor may need to kick in briefly to pressurize lines. Maybe? Quote Link to comment Share on other sites More sharing options...
Generalbeluga Posted January 16, 2013 Report Share Posted January 16, 2013 I thought this was a sound added so sight impaired people would be able to hear the car. I believe Toyota had to add something similar to the Prius a few years back after some run-over accidents. Quote Link to comment Share on other sites More sharing options...
valkraider Posted January 16, 2013 Report Share Posted January 16, 2013 It's not a sound for blind people. If so then it would only protect blind people every now and then and only for 30 seconds after starting the vehicle. Also, if it was for blind people then what would be the point of making the noise when the car is in Park, not moving, and in the case of my Energi - plugged in to the wall? Quote Link to comment Share on other sites More sharing options...
darrelld Posted January 20, 2013 Report Share Posted January 20, 2013 I have that sound too with climate control off. I always thought it was the stepper motors positioning the radiator shutters. Quote Link to comment Share on other sites More sharing options...
valkraider Posted January 20, 2013 Report Share Posted January 20, 2013 That could be it. There are all kinds of things which happen for short periods at start up - but may not be needed every time. It could be the AC pump pressurizing. It could be the oil pump pressurizing. It could be coolant pumps or the active shutter motors. All kinds of things. But it seems that it happens to most of us and only for short times and only occasionally.... Quote Link to comment Share on other sites More sharing options...
Generalbeluga Posted January 21, 2013 Report Share Posted January 21, 2013 The good news is that we have three years or 36,000 miles to figure it out! Quote Link to comment Share on other sites More sharing options...
Ubernuts Posted April 4, 2013 Report Share Posted April 4, 2013 But that does not explain the noise which should not be there. There is something definitely not correct here!I forgot to post back that Ford's final answer to the dealership was that the noise is normal for the C-Max at start up with the A/C on, do not replace the part. The service lady gave an explanation from Ford that was similar to what Antone posted above. Quote Link to comment Share on other sites More sharing options...
Sparky Posted April 4, 2013 Report Share Posted April 4, 2013 (edited) The C-Max has a 12v electric motor driven vacuum pump. The vacuum may be used for climate controls (duct diverter doors) or power brakes. The a/c compressor is powered by the high voltage lithium battery. The a/c compressor is similar to what is used in a home air-conditioner. It is not belt-driven. The link below shows some of the features: http://media.ford.com/images/10031/2013_CMAXHybrid_Hero.pdf Edited April 4, 2013 by Sparky Quote Link to comment Share on other sites More sharing options...
dtorres Posted April 5, 2013 Author Report Share Posted April 5, 2013 In my case I'm convinced it's the electric A/C compressor and it's been getting louder when it runs. I'm just going to wait till the part wears out more and the noise reaches a level where they can't say it's normal. Quote Link to comment Share on other sites More sharing options...
RachelnLa Posted April 5, 2013 Report Share Posted April 5, 2013 Before shutting down the car, I turn off the ac. If not, when I start it in the morning it starts in ev and it makes a buzzing sound under the hood. Turn ac off and it stops. Quote Link to comment Share on other sites More sharing options...
Hatchman Posted April 5, 2013 Report Share Posted April 5, 2013 Our car has made the sound since day one. Even with the car just sitting in the garage, checking out the Sync functions. It will make the noise every 5 minutes or so for about 5 seconds (roughly). I think it may be that electric driven vacuum pump for braking. Perhaps it is cycling to create the correct pressure/vacuum and then switching off. Whatever it is, it is loud and sounds like something is dying. Next time someone changes their oil, just lay under the car with the under shield/tray off and listen to where the sound comes from. Or I'll do it in about 9000 miles. Ubernuts 1 Quote Link to comment Share on other sites More sharing options...
C-MAXER Posted April 5, 2013 Report Share Posted April 5, 2013 I have a couple of other hybrids and yes the "it sounds like a computer fan going bad" is the electrical A/C compressor running. Another common noise is the brake system periodically priming itself to maintain brake line pressure (it doesn't run off vacuum from the engine like in a conventional car). Quote Link to comment Share on other sites More sharing options...
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