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I am having a strange issue with my 2013 Pilot EX-L (98K Miles): The interior of the car gets strangely warm, AFTER the car has been parked for a number of hours, in the shade. It feels as if the heat was on inside the car, after it had been turned off & parked for a while. This has been happening consistently for months, enough for myself & others to notice it. As an example: I did a bunch of city driving the other day. After I finished working, I parked in a garage, not near any vents or anything different, around 630P. I got back to the car around 10P, and it was VERY warm inside.

The temperature gauge does not fluctuate at ALL, the car doesn’t hesitate to start, coolant levels look good, no check-engine light... I had the same issue with a classic car that I own, and in this case the valve seals were bad. It is tremendously expensive to fix, and hard to diagnose (you have to take the engine apart to examine the valves to determine if they need to be replaced). Before I go ahead and do the repair, has anyone experienced anything similar?
 

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Is your car using oil? If not your valve seals aren't a problem. What is the ambient temperature you are parked in? Any car will get warmer with a warmer outside temperature, especially with the window closed. Same as with cold temperatures, the inside will be cold also after parked for a while. I don't think you have a problem.
I
I am having a strange issue with my 2013 Pilot EX-L (98K Miles): The interior of the car gets strangely warm, AFTER the car has been parked for a number of hours, in the shade. It feels as if the heat was on inside the car, after it had been turned off & parked for a while. This has been happening consistently for months, enough for myself & others to notice it. As an example: I did a bunch of city driving the other day. After I finished working, I parked in a garage, not near any vents or anything different, around 630P. I got back to the car around 10P, and it was VERY warm inside.

The temperature gauge does not fluctuate at ALL, the car doesn’t hesitate to start, coolant levels look good, no check-engine light... I had the same issue with a classic car that I own, and in this case the valve seals were bad. It is tremendously expensive to fix, and hard to diagnose (you have to take the engine apart to examine the valves to determine if they need to be replaced). Before I go ahead and do the repair, has anyone experienced anything similar?
 

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If you find that there is a lot of ambient temps in the cab get some window rain guards and crack the windows down a 1/2 inch ..also get yourself a good front window shade that fully covers the windshield... I find it odd that valves would have anything to do with the Hvac system when the engine has been turned off with the newer engines... i saw this with the old 454's and 320s .. there are no fans still spinning to push the heat from the heater core. I experience the same with both my 06's and my fisher price edition 2015 same thing with the heat.. BUT when it's cool in the garage and hot outside the cab stays cool for hours at park.. so its a toss up ..totally normal ..
 

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Any issues with the rear air vents? I’m wondering if the rear air blend door is stuck in the heater position. On the 2005 Pilot I believe the rear heater core always has hot coolant flowing through it regardless of the climate control setting. I’m not sure if your Pilot is configured the same way.
 

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Discussion Starter #7
Any issues with the rear air vents? I’m wondering if the rear air blend door is stuck in the heater position. On the 2005 Pilot I believe the rear heater core always has hot coolant flowing through it regardless of the climate control setting. I’m not sure if your Pilot is configured the same way.
I will look into this, thank you for mentioning!
 

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If you really want to dig into this, get a thermometer that also measures humidity. Check what it shows when you park, then measure what it is when you return. A rise in humidity can make it feel warmer.
 

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If you really want to dig into this, get a thermometer that also measures humidity. Check what it shows when you park, then measure what it is when you return. A rise in humidity can make it feel warmer.
Great idea, thank you so much for the response!
 

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My '61 Impala was quite the mosquito fogger with bad valve guides... New cars really don't have these issues so I'm pretty confident in saying you don't have that issue, especially if you aren't losing any oil.

I think you need to grab one of those little thermometers you can leave on your dresser and put it in the car. In the garage ours never get all that warm but even in the shade outside there is plenty of radiant heat.
 

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Thank you everyone for the replies. It is just strange because I know the car very well, and this change is something that is significant enough for me to notice. It never did this before, and now I can feel this warm, humid air inside of the car after it has been parked for hours inside a garage. I obviously take summer time and radiant heat into consideration, but again the heat inside the car is so significant, it is enough for me to notice.

Is this a sign that the water pump can be on its way out? I figured if the water pump was having issues, it would definitely reflect it on the temperature gauge inside the car.
 

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Just wondering if it might not be a precursor to clogged A/C drains overflowing into the cabin. It's a quick fix: just pinch your center nipple and shove a barbecue skewer up your dangling hose. Not as painful as it might sound ?, and if nothing else can rule out this common problem.

https://www.piloteers.org/threads/2005-honda-pilot.164779/#post-1624906
 

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Give it a few more weeks if he's in the winter belt ..he's going to want the heated cab :) hell i do! .. :p still trying to figure out how to adapt the heated steering wheel to my 2015 series Pilot ..
 

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The workshop manual offers access to the HVAC self-diagnosis and troubleshooting displays in the console. The self-diagnostic procedure causes the systems to cycle through the whole array of system functions, including the various actuator, blend and recirc door motor functions. The display then lists everything that didn't work correctly, using a combination of mode indicators and illuminated segments in the temp display. The whole procedure is too involved to try and copy into a single post. Look at the HVAC pages in section 21, starting at 21-118 for the Climate Control self-diagnostic functions without HDS. User TahoeFever posted the 2012 workshop manuals as a PDF attachment in the last few months. Use the Search function to find and download the files. The HVAC diagrams and diagnostics there are consistent for all years in the 2011-2015 model run.
 

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I am having a strange issue with my 2013 Pilot EX-L (98K Miles): The interior of the car gets strangely warm, AFTER the car has been parked for a number of hours, in the shade. It feels as if the heat was on inside the car, after it had been turned off & parked for a while. This has been happening consistently for months, enough for myself & others to notice it. As an example: I did a bunch of city driving the other day. After I finished working, I parked in a garage, not near any vents or anything different, around 630P. I got back to the car around 10P, and it was VERY warm inside.

The temperature gauge does not fluctuate at ALL, the car doesn’t hesitate to start, coolant levels look good, no check-engine light... I had the same issue with a classic car that I own, and in this case the valve seals were bad. It is tremendously expensive to fix, and hard to diagnose (you have to take the engine apart to examine the valves to determine if they need to be replaced). Before I go ahead and do the repair, has anyone experienced anything similar?
Why were the leaking valve seal causing that issue with the classic car? Was blow-by oil continuing to burn in the exhaust system somehow while the car was parked? Was the exhaust just getting extremely hot while the car was running and then radiantly heating the cabin more than expected while parked?

In any case, if for some reason your engine is exhausting an unusually large volume of uncombusted hydrocarbons (either fuel or oil) then I suppose perhaps you could be getting some radiant heating from the exhaust system, perhaps. Seems a bit unlikely though. Alternatively, I think your generation of Pilot normally opens the HVAC recirculation blend door after being switched off for some minutes. If your blend door has seized or the actuator has burned out, leaving the car permanently in recirculate mode, then I can see that leading to increased heat retention, though again I'd be slightly surprised if it was all that significant. It is however my current best guess. As the previous poster suggested, run the self-diagnostic and see what it says; it should be able to self-monitor that blend door actuator.

Cars do certainly heat up after being parked; there's generally a hot exhaust immediately below below the cabin, and a hot engine immediately in front of it, commonly with the very very hot catalytic converter sandwiched between the engine and the cabin. In the case of longitudinally oriented trucks and cars with the transmission behind the engine and extending underneath the cabin, the effect can be even more pronounced. Though as you say, this is a change from the car's well known behavior, so I'm just trying to make best guesses. I'll second the thermometer idea, and raise you a suggestion that you invest in a Non-Contact Infrared Thermometer, which can be had for under $15 shipped from Amazon or the usual scumbags. Take that and go on a hot spot hunting expedition 15 minutes after you've parked the car; see if you can work out from whence the heat is gaining ingress.

It's certainly possible that a very subtle electrical fault could be leading to resistive heating in the cabin; there are large-ish DC motors all over the interior of the Pilot; 7 in the front seats, one in each door panel, one in the sunroof, two blower motors (with associated resistive droppers for speed control in the air stream in the cabin) and presumably two heated seats. Additionally the radio and particularly the amplifier modules will generate heat when powered, so conceivably a bad power distribution relay that's stuck on, or a module (like the radio amplifier for example) which is failing to honor the body management command to sleep when the ignition is off, could be steadily pumping BTUs into the cabin while the car is parked. That should be easy for a mechanic (or non-mechanic with suitable equipment) to test for; just measure the quiescent current being drawn from the battery while the vehicle is parked; it should be exceedingly low; under 100ma (0.1A) for your car, after it's had a half hour or so (maybe less, I forget) for all the modules to completely enter their sleep state. Testing for it would realistically require a DC ammeter clamp around the negative battery lead, or a very steady hand to introduce a wired ammeter inline to the negative lead after the engine has been turned off, without breaking the circuit or frying the ammeter fuse (inrush current in cars tends to be substantial).
 

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I am having a strange issue with my 2013 Pilot EX-L (98K Miles): The interior of the car gets strangely warm, AFTER the car has been parked for a number of hours, in the shade. It feels as if the heat was on inside the car, after it had been turned off & parked for a while. This has been happening consistently for months, enough for myself & others to notice it. As an example: I did a bunch of city driving the other day. After I finished working, I parked in a garage, not near any vents or anything different, around 630P. I got back to the car around 10P, and it was VERY warm inside.

The temperature gauge does not fluctuate at ALL, the car doesn’t hesitate to start, coolant levels look good, no check-engine light... I had the same issue with a classic car that I own, and in this case the valve seals were bad. It is tremendously expensive to fix, and hard to diagnose (you have to take the engine apart to examine the valves to determine if they need to be replaced). Before I go ahead and do the repair, has anyone experienced anything similar?
The workshop manual offers access to the HVAC self-diagnosis and troubleshooting displays in the console. The self-diagnostic procedure causes the systems to cycle through the whole array of system functions, including the various actuator, blend and recirc door motor functions. The display then lists everything that didn't work correctly, using a combination of mode indicators and illuminated segments in the temp display. The whole procedure is too involved to try and copy into a single post. Look at the HVAC pages in section 21, starting at 21-118 for the Climate Control self-diagnostic functions without HDS. User TahoeFever posted the 2012 workshop manuals as a PDF attachment in the last few months. Use the Search function to find and download the files. The HVAC diagrams and diagnostics there are consistent for all years in the 2011-2015 model run.

My guess is you have a failed heater core control valve. The valve itself could be bad, but more likely, theactuator that controls the valve could ba disconnected, or have failed.

This valve is controlled by the vehicles hvac system. It opens when the car needs heat, or is defogging the windshield. If you have a premium ac system, it will flow to reheat the air chilled by the ac coil to the set temperature.

Whenever this valve is open, it fills the hezter core(s) with hot water. If it is stuck wide open, that is a lot of hot water. When you shut the car off, that residual heat is transferred into the cabin. That will then equilibrate, and the vehicle will cool to ambient temp.

These valves are in the engine compartment, near the firewall. They are not expensive, <$50 aftermarket, probably $100 from Honda plus installation.

I'd actually take it to a dealer, as I think there is a 50/50 chance the problem is the actuator, that can be a huge and tricky job to fix.

Astrobuf
 

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This may be a long shot, but I have to wonder if one (or both) of your catalytic converters is overheating. If you have a Bluetooth OBD sensor, you can use an app like Torque to see the temperature of the cats. I haven't done it in a while, but I know the cats can get pretty hot (normal operating temperature is roughly 1200 to 1600 degrees F).More pollutants in the exhaust results in higher cat temps. Is your gas mileage worse than normal? Maybe the engine is running a bit rich. Either way, I agree with Astrobuf, sounds like a job for the dealer.
 

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There is no heater control valve. Coolant flows freely through the two cores at all times while the engine is running. Further, the blend/mixing doors in the air boxes are electrically operated, and "fail in place" when the engine is stopped. That means that the doors may be partially open when the engine stops, and they stay partially open. The actual mass of hot water in the cores is pretty small, such that there will be minimal heat transfer out when the fans aren't running.

You can "force" the blend doors closed by running the cabin temp setpoints down to minimum prior to engine stop. If that slows or stops the symptom the OP reports, the system is working as designed. The diagrams/drawings of the HVAC boxes don't show any separate seals on the blend-door flaps or their seats. Doesn't mean there aren't any, just that they are not separate replacement parts. In some other "vintage" cars in the fleet, those seals are similar -- but we need to make them rather than buy them as service parts. They typically last decades though, and materials have improved a ton between then and the Pilot.

Another important thing to look at is coolant level in the system. Look at the overflow bottle/reservoir, but also look at level in the radiator with the engine cold. There should be no air or vapor space above the liquid level in the radiator. If there is much at all, start your search for leaks at the hose and connection to the bottle, and replace the radiator cap itself with a new genuine Honda cap. The coolant itself should be on your five-years replacement schedule, and it's a Good Idea to replace that cap and the thermostat at the same time.

The coolant temp gauge in the dash is "characterized" so that the needle stays very steady so long as the coolant is within its "normal" operating range. Changes in temp between 180ºF and 210ºF makes almost no difference to the gauge reading in my car. A cheapo bluetooth OBD module and a free phone or table app will let you watch all three coolant temp sensors in real time, so you can see how Honda protects you from worrying about coolant temp changes until it's too late. Regardless, excessive coolant temp at shutdown, perhaps caused by low coolant level, could easily present the OP's symptoms if severe.
 
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That means that the doors may be partially open when the engine stops, and they stay partially open.
I'm not certain (and I don't own the car any more so I can't validate) but I want to say my 2011 Pilot liked to sit quietly for 15 minutes after you'd turned it off, then wake up and move the blend/recirc doors around a bit, then go fully asleep. However I may be conflating that with the RDX we had of the same generation, though I believe both had near-identical HVAC control strategies.

In any case, I do agree with you that the coolant left in the heater cores (2 cores in the Pilot, I think) should have so little mass as to be negligible, at least compared to the exhaust system slung underneath. It's a bit of a mystery actually.

Also, hi from somewhere else in the high desert!
 
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