brian0918

2006 Accord V6, 123k miles.

History: A/C was only getting cold air to the passenger side. I assumed it was low on refrigerant (which was the problem last year when I added some to cool it down). I added some plain R-134a, but the refrigerant gauge was showing that the pressure was in the red zone. It was a hot day so it might have still been within range. I stopped adding refrigerant, and let it run for a little bit, and then heard a loud PSSSSHHHH sound and saw the freon come out. I'm assuming this was some sort of pressure relief valve. It appeared to come from around the compressor.

So assuming that the pressure was too high, I started letting some freon out. Then I was able to rev the engine higher, but if I went too high it would go PSSSHHH again and let more freon out.

So I finally rented a gauge set, and checked the pressures. With the A/C off, the pressures were equal at 120psi (ambient temp about 100).

When the A/C was turned on to full blast, the low side pressure immediately dropped to 90psi, then quickly pulled down to about 35psi, where it stayed.

On the high side, it first increased to about 130psi, then started dropping down to 110-120psi. The high side needle was also fluttering slightly. I didn't see any bubbles in the gauge.

Any idea what is going on here?

ChuckleBox

Have you checked out your cabin filter to see if its clogged? I would say it sounds like a blend door is jammed but it seems like you at least momentarily have normal pressure so that seems unlikely. I'd also try to have a look at the evaporator case to see if it's holding water. I don't think it's a mold issue or the issues would be accompanied by a funky smell. It could be a loose hose too.

brian0918

I haven't checked the cabin air filter in a while, so I will check it out, but I did replace it last year sometime. No bad smells anywhere.

Earlier this year I heard the blend door motor on the driver's side clicking constantly, like in this video. It hasn't done the clicking in a while, so maybe it's stuck in a certain position, not sure.

ChuckleBox

If you changed the cabin air filter last year, I doubt that's the issue but it could be the blend door. Whatever you find out, let us know. Good luck!

brian0918

The repair shop couldn't find any leak, and said it was overfilled. I guess I can't trust the OEM gauges I rented from Autozone then. They were showing about 120 High, 40 Low.

They evacuated (only for 15 min) and recharged and added the oil. So now I feel safer running it.

But the driver side is still warm (ambient temp) while the passenger side is cold (but only about 60F)

The cabin air filter had some stuff in it, so I sprayed it out with air and put it back in. I don't think it made any difference.

What do you think - blend door actuator/motor? Is there anything a mode 6 scan tool could show me? I have one of those Lemur bluetooth scanners that works sometimes.

I might also try cleaning the condenser with NuBrite coil cleaner to see if it helps bring down the passenger side temp.

brian0918

I found the diagnostic test for the climate control system, and got these results. The test was at night after the car was just started.

• In-car temp: 81F
• Ambient temp: 79F
• Solar sensor: 01 (dark)
• Coolant temp: 183F
• Evap Outlet Temp: 57F
• Driver's Air Mix Opening: 31% on Max Cool, 101% on Max Hot (F1 value)
• Passenger Air Mix Opening: 2% on Max Cool, 99% on Max Hot

So it does look like there's a problem with the driver's blend door not shutting all the way.

But I'm also wondering about the evaporator outlet temperature being high. Is this just because I didn't have it running for a while? It might explain why the passenger side doesn't get very cool.

ChuckleBox

I’m a bit stumped by the high evap outlet temp to be honest. Personally, I'd just try to fix the blend door before speculating on another potential issue but that’s also just because of the limitations of my knowledge on a/c systems.

brian0918

Some updates:

I took the evaporator temperature sensor out to test its resistance vs temp, and it was working fine over the whole range (about 35F to 90F). So I have no idea why it's reporting that the evaporator outlet temp is 60-65F. Would that indicate a problem with the evaporator?

As far as the driver blend door: I took the actuator motor out, opened it up, and found the resistance wheel covered in grease (from the plastic gears). Other people have said they cleaned that up and it stopped the actuator clicking constantly. So I cleaned it up and reinstalled it, but it it is still reporting "d2" for the door opening percent (about 30%) instead of 0 (like the passenger blend door). I noticed that as I increased the temp slowly, it would jump from "d2" to 5, 15, etc. So it's almost as if at the lowest temp, it's getting confused. Or I'm interpreting "d2" wrong.

The actuator looks like it is shutting the door all the way, so it may not actually be malfunctioning. Could the door have a leak?

Other than that, I also checked the heater control valve and cable under the hood, and confirmed that it is shutting all the way when turned to max cool. So it's not letting hot coolant to flow in.

Any ideas where to go at this point? The driver's side is still much warmer than passenger's side, and the passenger side is not getting low enough.

ChuckleBox

Wow, yeah, this one's bizarre. You don't think it could be something as simple as a loose hose?

brian0918

There's no hissing anywhere like something is leaking. And I tried slowly unscrewing and screwing the hose back on, so I could tell when it stopped leaking. I also re-wrapped the threads with teflon tape. It's definitely sealing up.

ChuckleBox

Wow, yeah, I hate to say it, but I'm totally stumped!