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acramstr, ASE Master Tech
Category: Acura
Satisfied Customers: 5359
Experience:  ASE master tech ,CA smog, ASE L1
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MDX: I just replaced my battery about 2 months ago or so, and

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I just replaced my battery about 2 months ago or so, and now the battery dies after several days not starting it (using our other car). We had a HFL issue in our old car that happened in a similar fashion and we had to replace the whole board they said. I have a feeling I just need to replace the HFL in the 2008 MDX, but need the part # XXXXX where it's located (near rear view mirror or middle of back seat area behind AC unit).
Hi Sir or Madam, welcome. I'm Steve. And I will be assisting you today. the HFL unit is in the back of the console. The back just pulls off . the part number is XXXXX it cost about $250. Also check that the a/c compressor stops when you shut the a/c off. We see the compressor relay stick in this model and drain the battery as well.
Customer: replied 4 years ago.

Is there a straight forward way to check the compressor relay? Saw this reference online "If the relay sticks [ed: closed] when the ignition switch is turned to LOCK (0), and the compressor was running, it creates enough parasitic draw to discharge the battery."

If you had to explain that to a non-technical would I test the relay to see if that's also an issue? For example, I get cold air when AC is on and haven't had issues in the past with it.

Thank you

Ok, Get a flash light and look at the a/c compressor ( bottom under the alternator close to radiator) Have someone turn the climate control off and on. You will see the very end if the compressor (black disc) start and stop when the a/c is turned off and on if it does then the relay is ok. If not then the relay is bad.


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Customer: replied 4 years ago.

Well, I haven't checked A/C Compressor yet, but I took it to Goodyear and was told the alternator was failing 3 out of 10 times, especially while at idle state...something about it being way too high, more or less burning the battery up. They weren't sure this was causing the SUV to not start, but obviously I didn't want to spend another dollar there after replacing the alternator so I left without having anything else (i.e. electrical analysis) done.


Could it be related to the instrument cluster? Maybe the Starter or maybe I should check all the fuses? I haven't experienced the issue since changing the alternator at least, but I also disconnected the HFL. I should also point out there was an aftermarket flip down DVD player installed before I bought the car, but it wasn't working (beyond the embedded overhead light when door is open).


Basically, trying to figure out if the alternator could have been causing this or if I will eventually need to keep probing.

I would have the system checked for a draw with the key off ,With and without the HFL Unit plugged in see if there is a difference. Shorted HFL Units are a big problem in this model.