AC question

[HoosierDaddy]

The AC in my 2016 seems to take longer to cool the car down in high heat conditions than previous years. A local shop had a free AC check come-on, so I took it in. They concluded everything is fine because the AC put out 59 degree air in their open air bay with 102 outside temps.

But the car definitely takes a longer to get the interior down to the 72 degree setting than it did last summer after getting superheated while parked in the sun. My father's place is about 20 minutes away and it takes almost 15 minutes on the drive home to get to what feels normal. When it gets into the mid 120s, which it does every year, I don't think this is going to cut it but no problems in prior years.

Now I don't park in the sun very often, so I guess its remotely possible I'm imagining a change. I was thinking it may need a little refrigerant but they didn't do any measurements and already had someone else in the bay before I found out they just measured the temp from the vents.

Anyone know what 59 degrees really says about how well the AC is working?

Aren't those free checks to get someone in that needs something done? So, if they suspected it was low on refrigerant I'd expect them to check to see and make some money on the job.

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[ice445]

Could be the early stages of the dreaded AC Evaporator core leak/failure. Has your car ever had that replaced? With that said, the outlet temp seems okay for 102 ambient, but I don't have a good baseline to compare it to. Hopefully someone else can chime in on that.

 

[ugstang17]

If they did not check the refrigerant level there could still be a potential issue. A cold output temp does not always mean a good thing. When the refrigerant in a system gets too low the temp across the evaporator coil can get extremely low. When this gets TOO low the evap coil will freeze on the outside blocking air flow (The condensation is freezing to the fins and blocking air flow in this case). I had this happen on my home AC unit that ran R-22 at the time. Thankfully my father spent 35 years in Refrigeration and AC and boilers and had some spare R-22 and his gauges and topped the system off.

I know it sounds counter productive to think that the AC supply temps can be too low due to low Refrigerant but they can. Had it not been my father explaining it to me I would have thought I was being BS'd by someone. After he went through the theory and explained it for the third time it made sense. That was about 15 years ago so I have since forgotten the details of the how's and why's because dad gets deep into the theory when he starts explaining it and I'm just an electro-mechanical guy.

You may wish to take the advice of ice445 and have it checked with the gauges (assuming they did not since you never mentioned that) and find out for sure. Inhibited air flow is the other reason why an AC unit is taking too long to move enough air to bring the temp into its setpoint range in a specified period of time. You may wish to see if running the AC unit via outdoor air vs recirculating air makes any difference in recovery. Not sure how the cabin air filter plays into the air flow routing on these cars but I assume it is in line with recirculation. If clogged it would minimize air flow. Even a 10-20% restriction would slow down the air flow and alter the air changes per hour which directly effects recovery time.

 

[HoosierDaddy]

Could be the early stages of the dreaded AC Evaporator core leak/failure. Has your car ever had that replaced? With that said, the outlet temp seems okay for 102 ambient, but I don't have a good baseline to compare it to. Hopefully someone else can chime in on that.

Not replaced (unless they did it between unloading it from the transport and me getting there to drive it home).

Only issue ever was when just a few months old. On the last 200 miles of a 5,000 mile road trip started putting out barely cool air but also lost every other one of the normal fan speeds. Since I couldn't think of a single hardware cause for both, I disconnected the battery for a while and everything was normal after that.

 

[HoosierDaddy]

You may wish to take the advice of ice445 and have it checked with the gauges (assuming they did not since you never mentioned that) and find out for sure. Inhibited air flow is the other reason why an AC unit is taking too long to move enough air to bring the temp into its setpoint range in a specified period of time. You may wish to see if running the AC unit via outdoor air vs recirculating air makes any difference in recovery. Not sure how the cabin air filter plays into the air flow routing on these cars but I assume it is in line with recirculation. If clogged it would minimize air flow. Even a 10-20% restriction would slow down the air flow and alter the air changes per hour which directly effects recovery time.

No they did NOT do anything but measure vent temps. I assumed they would use gauges but they said they didn't. Maybe time to buy some and learn the procedures.

I bought several cabin air filters during a recent AutoZone price mistake ($4.19 for STP Max charcoal filter) but haven't put one of those in yet. About 28k miles on the car and about as many miles on the first replacement cabin filter I installed as the original so I'll check that right away. I would have guessed the filter was for outside air and not a factor here.

I set the driver AC temp when new and don't touch it with it on auto. In many previous cars I would start drives on outside air AC or windows down when the car was superheated inside and outside air was cooler even at 100+ but this car never seemed to need that (at least before) maybe automatic setting is smart enough to do that on its own.

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