Pressing gas pedal makes blower fan go faster

[FordSVTGuy]

Hi all - I was driving our 2015 Lincoln MKC yesterday and noticed that when I pressed the gas pedal, the speed of the blower fan/AC would speed up/intensify. A I let off the gas pedal, it would return to normal. This is new, never done it before. I turned off the AC and tried again and it still did the same thing. I stopped to pick up food, turned car off and then tried again on the way home. Same thing was happening. Any ideas at all? I think it might be something electrical in nature?

 

[oggb]

Alternator? Measure at the battery at idle then have someone hold the pedal at 2000-3000 rpm and check again.

 

[gathermewool]

It seems as if the alternator output voltage is rising as your RPM rises. Could be indicative of a problem.

My alternator will put out constant voltage from idle (even with many loads on) to higher RPM.

 

[Imp4]

Definitely check the charging system.

 

[atikovi]

Alternator output rises with engine speed. More volatge = higher fan speed. Circuitry should prevent major fluctuations as well as the pulley decoupler. Either of those could be a problem.

 

[vwmaniaman]

You have a battery that is telling you to replace it. Normally the voltage in your car is pretty constant because the battery sucks up the over voltage.

 

[zrxkawboy]

Battery or alternator...have them tested at your favorite parts store.

 

[FordSVTGuy]

If it is a battery, I’m guessing that the high heat and humidity here in the NE may have beat this down…. It’s not that old a battery…

 

[wag123]

IMO, the battery.

 

[Lyman]

My Jeep did all kinds of weird stuff when the battery went bad. It went crazy! I thought I had a major electrical short.

 

[SHOZ]

Some of the new cars with ECU controlled voltage regulator will cut the voltage output regardless of rpm.

 

[Kawiguy454]

newer vehicles have smart charging so the alternator will unload at times to save fuel. when this happens the blower is running from battery when alternator kicks in you get a couple more volts and it speeds up.

 

[FordSVTGuy]

newer vehicles have smart charging so the alternator will unload at times to save fuel. when this happens the blower is running from battery when alternator kicks in you get a couple more volts and it speeds up.

Interesting. I’ve not heard about this before. I’m going to start with checking the battery and then we’ll go from there…

 

[SHOZ]

newer vehicles have smart charging so the alternator will unload at times to save fuel. when this happens the blower is running from battery when alternator kicks in you get a couple more volts and it speeds up.

Saves on gas, hard on batteries.

 

[FordSVTGuy]

Well, I had the battery and alternator checked out at the local AA store. Everything was good. So ironically on the way home the check engine light came on. Throwing code PO 0299, under boost on the turbo. I turned off the cooling system completely and the sound was still there. Must be a turbo issue making the same sound as the fan on acceleration. There is a TSB noting that the wastegate actuator arm could become loose…. I don’t know what that would sound like, but my issue sounds like the a wish of air through the vents… going to the dealership next week. Thankfully under extended warranty…

 

[partspro]

Could also be the Manifold Absolute Pressure sensor, MAP reading off, not really a fan of turbo's

 

[Craig in Canada]

I know nothing about the car in question, but after hearing 1/ under boost, 2/ sound coming from under the hood loud enough for you to hear it with windows closed and AC fan blowing, I'm going to guess you have some kind of intake rupture, split, or sensor popped out of place after the turbo and before the intake manifold. If this was a BMW N54 or N55 I would say "charge pipe". You should be opening the hood and looking around, or leave it for the dealer I guess. Of course this is a "positive guess" meaning a replaceable plastic/composite part that isn't super expensive. "Negative guesses" of worst case doom and gloom would be a blown turbo and such.

 

[FordSVTGuy]

I know nothing about the car in question, but after hearing 1/ under boost, 2/ sound coming from under the hood loud enough for you to hear it with windows closed and AC fan blowing, I'm going to guess you have some kind of intake rupture, split, or sensor popped out of place after the turbo and before the intake manifold. If this was a BMW N54 or N55 I would say "charge pipe". You should be opening the hood and looking around, or leave it for the dealer I guess. Of course this is a "positive guess" meaning a replaceable plastic/composite part that isn't super expensive. "Negative guesses" of worst case doom and gloom would be a blown turbo and such.

Very close! I had time this morning to diagnose the issue further and once I removed the bottom engine shroud and crawled underneath, I found one of the plastic turbo tubes had separated from its joint. This was right up against the firewall and was thankfully easy to get to and reconnect. I cleaned both sides of the pipe connection and really tightened the clamp down. There was definitely some oil residue inside the tubing. Cleared the code and took it for a test drive. All working normally.

I guess it’s possible that the clamp that holds the connection worked its way loose over 6 years? I’ll be checking the clamp at each oil change from here on out…