Any Honda techs lurking out here? AC diagnostics...

[dick w]

My question is: what diagnostic info is available via the Honda i-HDS scan tool to diagnose operation of the auto climate control in specific and the AC in general? The climate control in our '16 Civic seems like it is not working as it did for years and I'm having a tough time getting the dealer to figure it out and get it solved. The problem is that it's taking a *long* time to cool down the interior when it's hot--like sitting in the sun for hours hot. It doesn't seem to be doing all it can do--or used to do--in terms of air volume (fan speed) and cold air output even when the interior is a lot hotter than the temperature set point. So, I'm wondering if the scan tool can tell what temperature it's sensing in the interior, what it's sensing from the dash sun sensor, what portion of available AC compressor displacement it's commanding, etc. The problem is that it is working at least a little bit, so it's pretty easy to blow off our reported issue. Dial the set points down to Lo or 60, and the air volume does go way up and the temperature does drop faster. I'm not clear on why it works so much harder to get to Lo or 60 from, say, high 90s in the interior, than it does to get to, say, 72.

Two additional data points from the vehicle's history. First, in the spring before we started observing this AC problem and before the weather and our use pattern was creating the conditions where it is readily apparent, it had its "Wire Harness, Engine Room - Honda (32200-TBA-A80)" replaced due to rodent damage. Without access to the Honda techinfo, I don't know what all subsystems that touches. Second, on its first visit for this complaint, they reported finding a leaking AC condenser which they replaced under the warranty extension for the condenser. Our observations were that this repair did not change its behavior. So, maybe a leaking condenser was a problem, but it wasn't *the* problem.

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[tacocat]

The HDS can see those sensors but you're asking an engineering question not an average tech question and most certainly not one a dealer will take the time to diagnose or compare numbers. The new 1234yf systems do not work well or consistent, it's the nature of the system when you are working with less than 1 lb of refrigerant.

 

[dick w]

So how do I get them to diagnose and fix the problem? Or do I just live with it for the remaining time I own the car? The tech feels cool air coming out and declares victory. (On my latest attempt to get this diagnosed, the service manager drove the hot car for a while and agreed that it wasn't working correctly to get the interior cooler faster. But the subsequent tech who worked on it felt cool air coming out, drove it in to the shaded shop, observed the fan slowing down--likely because of the sun sensor--and declared "works fine here".) This isn't an inconsistent problem--though it requires a certain starting condition--cabin temp way above setpoint temp--to observe and is probably not simple or quick to diagnose.

The Honda service information I'm familiar with--back when they printed manuals--had detailed procedures--engineering procedures, if you will--for diagnosing the simpler, software free, systems back then. Unfortunately, even then, many of these were complex and time consuming. (I recall the AC diags having detailed graphs that involved temp in, humidity, and temp out to diagnose what was correct and low refrigeration performance.) Much harder and more time consuming than 1) start car, 2) feel cool air coming out, 3) declare AC is working and move on to the next ticket.

I have only one choice for a dealer to work on it, unless I ship the car on a barge--$500 round trip--to another one.

 

[tacocat]

It's not a problem though, it's a characteristic of the vehicle and the a/c system. They all do it and a tech can't change the fan speed based off of the light sensor, that is an engineering issue of the car. Sounds like you should just manually control the a/c fan speed and temp to get the desired results if the auto is not working the way you like.

 

[dick w]

It's not a problem though, it's a characteristic of the vehicle and the a/c system. They all do it and a tech can't change the fan speed based off of the light sensor, that is an engineering issue of the car. Sounds like you should just manually control the a/c fan speed and temp to get the desired results if the auto is not working the way you like.

I think you are missing my issue.

Auto used to work the way I expect. Auto in our '18 CR-V still works the way I'm expecting. (I'm not new to auto climate control. Had it in an '04 TL, '09 135i, '12 Focus, '16 Civic, and '18 CR-V, not to mention countless rentals.) I'm not saying I want the tech to change the fan speed based on the light sensor--the vehicle does this on its own. (And I think the tech used that very change to declare that Auto AC was working. Well, yes, but only somewhat.)

I'm saying that I expect the car, in Auto, should try its utmost to cool the interior from 100+ to its 72 degree setpoint until it gets closer to the setpoint, and, progressively, backs off on outlet temp and fan speed as it closes in on the setpoint. It's not doing this. It used to. It used to get comfortable in, say, the 15 minute drive home from town if it had been sitting in the sun for hours. It no longer comes close. And the fan never gets above mid-speed--and lower than that if there are some clouds. And the outlet temp never feels as cold as it does in the CR-V under the same conditions or as it used to feel in the Civic.

I grant you my view is very subjective, not based on engineering/test data. That's why I was asking about the HDS data.

 

[longthaitran91]

I’m currently having my entire system replaced at the dealer because something internally broke inside and is circulating metal shavings throughout the system. It took over an hr for my ac to cool. When I checked my low side pressures it goes from low to normal.

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