AC stops blowing air after a period of time

Question

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

Answer 1

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.

Answer 2

"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.