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Weak A/C and Musty Smell in 2017 MDX - DIY Fixes?

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Laura J. · rep 0 · May 22, 4:59 AM · 1 replies · solved · Question

Vehicle: 2017 Acura MDX AWD

My 2017 Acura MDX with about 80,000 miles has developed a couple of annoying A/C problems. First, the air isn't as cold as it used to be, especially on really hot days. It still blows, but it's just not chilling the cabin effectively.

Second, there's a distinct musty, almost mildew-like smell that comes through the vents when I first turn on the A/C. It eventually fades a bit, but it's pretty unpleasant. I'm hoping there are some DIY maintenance steps I can take before having to take it in for a potentially expensive repair.

I've heard about cabin air filters and evaporator cleaning. Are these good starting points? Any specific products or procedures recommended for the MDX?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 4:59 AM

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ClearTheCode admin answer:

It sounds like your 2017 Acura MDX is experiencing two common A/C issues: reduced cooling performance and a musty odor. Both can often be addressed with DIY maintenance before needing professional intervention.

Here's a breakdown of steps you can take:

  1. Replace the Cabin Air Filter:
    • Cause: A clogged cabin air filter restricts airflow, reducing the efficiency of your A/C system and trapping moisture and contaminants that can lead to odors.
    • Procedure: The cabin air filter in your MDX is typically located behind the glove box. Open the glove box, release the damper arm, and unclip the stops to lower it completely. You'll then see the filter housing cover. Remove the cover, pull out the old filter, note its orientation, and insert a new one. This is a very straightforward DIY task.
  2. Evaporator Cleaning for Odor:
    • Cause: The musty smell is almost certainly due to mold, mildew, and bacteria growth on the evaporator core, which gets damp during A/C operation.
    • Procedure: You can purchase an A/C evaporator cleaner/fogger (e.g., Einszett Klima Cleaner, Kool-It). Follow the product instructions carefully. Generally, this involves spraying the cleaner into the A/C system's fresh air intake (often near the base of the windshield under the hood) or directly into the evaporator drain tube. Run the A/C on high with windows open to circulate and dry the system afterward.
  3. Check Refrigerant Level (DIY with caution):
    • Cause: Reduced cooling performance is often due to a low refrigerant (R-134a) charge, usually from a slow leak.
    • Procedure: You can buy an R-134a recharge kit with a gauge from an auto parts store. Connect it to the low-pressure service port (usually marked 'L'). The gauge will indicate if the pressure is low. If it is, you can add a small amount of refrigerant. Caution: Overcharging can damage the system. If the system is very low, it indicates a significant leak that needs professional diagnosis and repair.

When to See a Shop:

  • If replacing the cabin filter and cleaning the evaporator doesn't resolve the smell.
  • If adding refrigerant doesn't restore cooling, or if the refrigerant level drops again quickly, indicating a significant leak.
  • If you hear unusual noises from the A/C compressor or blower motor.
  • If the A/C system blows warm air consistently, even after a recharge, which could point to a failing compressor, expansion valve, or other major component.
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