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After leaving the car off for a few hours, and starting it up, the AC always works 100%, the fans blow very nice cold air and it can last 20+ minutes. Sometimes it never stops working fully (yay) but usually, when it's really hot (or humid maybe), the output of the vents slowly reduces until it's barely a trickle coming through (feels cold still, if set to cold). Meanwhile I continue to hear the blower motor going full blast and I haven't touched the controls at all.

Blower motor and a bunch of sensors were replaced as well as the control console for the climate system. Also had coolent drained and recharged, there were no leaks. Compressor seems to work perfectly fine. Switching vent controls from head to feet 'work' but you can barely notice due to the limited airflow.

I've already had about $2500 put into this issue and the Honda dealership has so far failed to reproduce the issue nor fix the issue.

I'm at my limits on suffering through drives with a failing AC system. I do not want to bring it back to the dealership as I cannot trust them and already threw away enough money there. Is there anyone who may actually know what the problem may be?

My running theory is something is freezing up internally. I've had mild success ramping the heat all the way up for a time to then get the cooling system to push a little more airflow through but it dissipates quickly and is objectively not at all worth suffering through the heat blast. Heating works fine in the winter, if that matters.

Edit: Pending repair of expansion valve

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  • When you say "... the vents slowly reduces until it's barely a trickle coming through." Does that mean the airflow is reduced, or the cooling effect is reduced to barely a trickle?
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Jun 29 at 20:09
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    If you take it off of A/C (put it on heater) and turn the temperature up, does it blow any better? I'm talking right away, not after a period of time. (I apologize if these questions seem odd, but I'm trying to get to a point ... please bear with me.)
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Jun 29 at 20:29
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    Not right away, no. It's the same for an extended period of time but you can tell that it's now pumping out low volumes of hot air instead of cold air.
    – Enigma
    Jun 29 at 20:45
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    The reason I was asking these seemingly "same" questions is because of how the air flow works through the system. You have blend doors which switch between the A/C's evaporator core down to the heater core. When you change from cold A/C to hot heater, if the evaporator core was plugged (the fins) and then getting saturated with condensation, the air should move better when going through the heater core. It doesn't sound as this is happening, so I'd discount this as being the issue.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Jun 29 at 20:51
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    Does this answer help? mechanics.stackexchange.com/questions/88334/…
    – HandyHowie
    Jun 29 at 21:17

2 Answers 2

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The evaporator is ahead of the heater core. If the expansion valve is faulty, it will make the evaporator core too cold. When this happens the condensation on the evaporator core freezes. This plugs the core with ice and restricts airflow. The ice doesn't go away until you shut off the car and outside temperature thaws the ice in the core. The next time you start the car, it will work fine until it freezes again. Wash, rinse, repeat.

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    That sounds highly probable and to my knowledge was not one of the things replaced. Shocks me to no end that, based on the description and details of the issue, Honda decided replacing the fully functioning blower motor and climate control system were appropriate first steps. Shame on me for believing in their process though I guess. Is an expansion valve replacement expensive?
    – Enigma
    Jun 29 at 21:45
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    The refrigerant has to be removed and recharged after replacement. The valve itself is inexpensive
    – Jupiter
    Jun 29 at 22:58
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    Honda did the same with me. And Nissan with my mom. Seems at best there's not great problem solving skills sometimes :-(
    – JeopardyTempest
    Jun 30 at 10:52
  • I don't know about a honda, but in my 1982 toyota, a knob on the AC "computer" that allowed you to change the setting to prevent icing up the AC. TH ac is super old school, so I dunno about yours.
    – Eric Brown - Cal
    Jun 30 at 19:58
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"I've already had about $2500 put into this issue and the Honda dealership has so far failed to reproduce the issue nor fix the issue." Unfortunately, dealers fall into two distinctive areas; customer oriented or just replacing parts, profiting without repairing a problem. Guess where you fit in? Dealerships supposedly have the 'expertise' pertaining to their brand and models but clearly your dealer isn't fixing your ac problem. Vehicle refrigeration isn't rocket science but does require an experienced person familiar with vehicle ac system diagnosing, troubleshooting and repairs to restore ac function back to factory condition. Based on repeatable symptoms, your dealer should have been able to reproduce the symptoms and not proceed to replace parts, whack a mole style, in hopes of eliminating the problem. When they failed to do this simple act to verify or at least ask you to drive into their service entrance at the moment you suffer the same issue, they should have been able to examine the problem up front. Incompetent at the least. Showing up to any dealer or repair shop with your repeating problem should be easy for competent mechanics or techs to determine where a problem lies. Perhaps access to the hvac enclosure is difficult to impossible to examine if it collected debris, aiding in blockage if icing built up. R134a systems may not be prone to icing conditions, depending on what's used to control the release of liquid refrigerant into the evaporator coils to create cold. Perhaps Honda is reluctant to tear apart the interior for access to replacing the expansion valve, which may be on the firewall and difficult to replace (if this failed and is used in Hondas). Experts can determine if expansion valves failed during the diagnostic phase, using refrigeration gauges. You may have to resort to communicating with your Honda regional or national rep(?) to escalate this unresolved issue to another level for proper handling.

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  • "Based on repeatable symptoms, your dealer should have been able to reproduce the symptoms and not proceed to replace parts, whack a mole style, in hopes of eliminating the problem." - Indeed, a local shop guy said he could reach in and access it without going through the firewall.
    – Enigma
    Jul 11 at 19:20

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