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I might not be understanding the scenario correctly but I do know that coolant flow thru the heater core is increased/decreased ONLY by engine rpm.......higher rpm, more flow, lower rpm, less flow. Coolant starts flowing thru the heater core the moment the motor is started.......coolant stops flowing thru the heater core ONLY when the motor is turned off.

There is no coolant flow thru the radiator when coolant temp is below about 176F but there is plenty of coolant flow thru the heater core when the motor is running. The heater core will remove a substantial amount of heat from the engine coolant just like the radiator does, but not as much as the radiator removes because the heater core is smaller than the radiator. They are both heater exchangers......they remove heat from the engine coolant.

Two factors to a good heater......heated engine coolant, with unrestricted flow thru the heater core, AND proper, under the dash, HVAC blend door operation. 54C/130F coolant temp gives 80F-90F vent temp on our V and both engine coolant and vent temps continue to rise with driving. I monitor CT2.......it's pretty much worthless.
 

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I am more intrigued on how many people are so concerned on what the temp gauge is showing during cold weather. I would be more concerned about it showing a high temp during extreme hot weather. I get in my 2018 V Touring on a 40 degree morning. I start up the car and start driving. Before I reach mile one, the heater is already blowing warm air......a/c turned off. By mile two it’s getting too warm in the car at the setting of 74 degrees. I never wear a sweater or jacket in the car...... too confining. At mile 3 I have to turn it down to 69 degrees. I could care less what the temp gauge is showing. The car is running fine not stalling. It eventually reaches it normal temp range. I love the car.
I have no issues with the car's heat capabilities in 40F weather. My issue is when the temps drop below 20F more or less. Below that, as was already mentioned, the remote starter makes things worse as it blows cold air with max fan speeds onto the windshield, creating frost in some cases when the cabin is humid. At temps above freezing, things are manageable.
 

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Has anybody had any satisfaction in remediating the cabin heat problem? The heat has never been strong, but it's worse than ever now. It takes forever for the temperature gauge to reach operating temperature, and as soon as you turn the heat on, the coolant temperature gauge plummets, and there is little to no cabin heat. The gauge only rises again under acceleration, and as soon as you stop at a light or coast, it plummets again and there is no heat. In case you're wondering, this isn't only occurring in extreme cold, this happens in 40+ degree weather. The only time the heater actually works and the engine maintains operating temperature is when it's so warm you don't need heat! According to Honda, everything is operating normally. Has anybody had any success in getting Honda to fix this problem? Is it too late for a lemon law buyback on a 2017?
Seems like your thermostat is stuck OPEN and not allowing engine to warm up. Simple fix. Replace thermostat.
 

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I might not be understanding the scenario correctly but I do know that coolant flow thru the heater core is increased/decreased ONLY by engine rpm.......higher rpm, more flow, lower rpm, less flow. Coolant starts flowing thru the heater core the moment the motor is started.......coolant stops flowing thru the heater core ONLY when the motor is turned off.
Which brings up an interesting nuance with the 1.5T engine and it's CVT.

The engine is purpose designed for CVTs, which love torgue.. and it provides essentially maximum torque to the CVT from about 1800 rpm all the way to near red line.

I think most drivers will observe that under most driving conditions their actual engine rpm is rather low... between 1500 and 2200 in normal drive mode. So your comment is relevant here.. because not only is this engine extremely efficient, so is the CVT, and they actually present a low rpm driving scenario in many cases.. which runs counter to the desired outcomes from coolant circulating through the heater core.

Sport mode will move operating rpm range up about 1000 rpm under the same driving conditions, so it makes complete sense that Sport mode helps heat the cabin faster..... more fuel, more heat, more rpm, more coolant circulation through the heater core.
 

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Has anybody had any satisfaction in remediating the cabin heat problem? The heat has never been strong, but it's worse than ever now. It takes forever for the temperature gauge to reach operating temperature, and as soon as you turn the heat on, the coolant temperature gauge plummets, and there is little to no cabin heat. The gauge only rises again under acceleration, and as soon as you stop at a light or coast, it plummets again and there is no heat. In case you're wondering, this isn't only occurring in extreme cold, this happens in 40+ degree weather. The only time the heater actually works and the engine maintains operating temperature is when it's so warm you don't need heat! According to Honda, everything is operating normally. Has anybody had any success in getting Honda to fix this problem? Is it too late for a lemon law buyback on a 2017?
In order to pursue a Lemon Law case, you have to have taken the car in for service on multiple occasions, and keep all your paperwork, and keep a personal journal...it normally addresses multiple issues.
If you live in a hot weather state, as I did, you have to open windows to let heat out of the car, and it takes a while to feel the cool temp. I don’t have a heating problem in MD.
 

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From what I have observed in past vehicles (motor idling), I'd bet you would observe rapid coolant flow exiting the disconnected return heater hose of the 1.5L, similar to the rapid flow of water coming out of a garden hose. The water pump is not a positive displacement pump, but it will move/flow a substantial amount of coolant, thru both heater hoses and the heater core, even at idle rpm.

If you don't believe me, try disconnecting the return heater hose then start the motor. Get ready for a real mess, real quick (IF the hose slips out of it's clamp)......for a few seconds anyhow.:eek:
 

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I’m pretty sure the lower grill in front of the intercooler has 3 shutter blades/slats that open/close while the upper grill has 4 shutter blades/slats. Sounds like your a/c compressor is engaged, since the efans are running in cold temps. I’m thinking running efans/open crazy shutters are fighting against heater performance.

Gorilla tape....👍👍.
Sorry. My post may have been confusing. To get max heat (and fastest also), I always keep Auto temp switch off (to keep shutter closed and fans off). This should be the normal mode of manual operation for all that are not happy with cabin temps (and it can not but help in the OD concern area too) It is a minor hassle to do,,since in my option, the Auto on fan speeds runs to fast anyway. :)

Since the intercooler area has no lower shutters, I use duck tape to maks off that rea that normally direclty vents to the intercooler. The upper shuters and fans off should be closed in most conditons with the Auto switch off by design.

For my climate, I am just trying to stop as much excessive cooling engine air flow without a total rad blockage attempt, since I am not in extreme cold conditions. This week most nights where in the low teens. After all this is "warm" Colorado as Honda has indicated by their noTSB needed service areas in Colorado. However, I disagree with Honda's Colorado temp assesment (ok, maybe on the CO/Kanass border it is warmer), so just helping them not to have an engine OD warratny issue and a warmer cabin for me- at least a little warmer. LOL
 

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Are you sure there are no lower shutters (in front of the intercooler)?......our '17 V has 3 lower shutters and 4 upper shutters.
 

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Here is a measured reference point. Driving home this afternoon the outside temperature was -15C (5F). I had a thermometer placed inside the defrost vent and monitored the engine coolant temperature on the phone (BlueDriver). Between 57C (135F) and 70C (158F) coolant temperature there was 24 - 27 C (75 - 81F) difference between the engine coolant and the vent temperature. 70C was the point when I reached my destination (3 miles away) The fan was set on the 3rd "block" with a mixed defrost and feet airflow. When the monitoring started I was about half way home and had already shifted from S to D i.e when the red strip appeared at the bottom of the thermometer.
 

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Are you sure there are no lower shutters (in front of the intercooler)?......our '17 V has 3 lower shutters and 4 upper shutters.

I will check again, but pretty sure, you will see the AL of the intercooler when the shutters are closed above. And I think a few years ago others were noting the same. On mine, it looks like it is "missing" one slat at the botton vs a total blockage.

That is the reason I was trying to stop the lower air flow. It is not much, but a reasonable, safe and easy "fix" vs total masking off the grill vents (plus one muffles the horn also.)

I initally masked more, but even in Jan some days we get 70F day temps and the next day drops 40-50f. Wild ride and not the CRV only.
 

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This worked for me...single digit daytime temps recently and it was fine,

2018 EX-L with the 1.5l, we live in a cold climate

My wife mostly drives this vehicle - Now into the second winter and was thinking about the long warm-up time we have experienced with this vehicle. Started thinking about the active grill shutters and what their role may be in this. After searching around the Internet the grill shutters should go through a start-up sequence when the motor is started...initially they should be open, should cycle close and open, then close. Mine did nothing...

I looked at the fuse(s) involved and there are two fuses controlling these shutters, one for the fog lights and lower grill and the other for the upper grill (and engage the system)...fuse #22 (FR FOG/LWR_SG) was fine as the fog lights work, fuse #23 (MG CLUTCH/UPR_SG) looked fine but I replaced it anyways...and the shutters now look to be operating as they should on vehicle start-up.

I didn’t tell my wife, and she notice much quicker warm up time the first time she drove it. So, if you are having heat up issues, this is an easy thing to check. According to information I have found, the purpose of these shutters seems to be aerodynamics...but seems to me that they would have a role in helping to control/maintain engine temps?

Dealership was no help, in fact I tried to explain what I found after got the deer in the headlight look, didn’t reall seem interested?
Tom
 

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........On mine, it looks like it is "missing" one slat at the botton vs a total blockage..........
Yes, there is one slat less (3 slats) behind the lower gill vs 4 slats behind the upper grill. That's by Honda's design. That design is to allow constant air flow to/thru at least some of the intercooler so performance won't be reduced drastically.

I think your best bet would be to block off the upper grill and block off the bottom half of the lower grill, leaving the upper half of the bottom grill to feed airflow to the intercooler. By all means keep a close eye on your ScanGauge.
 

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Yes, I actually tried several configurations including the upper and lower masking opton. If you mask the upper plastic grill where the horn are, if muffles the horn sound considerable. If you mask agressive for the winer ambient temp, you can actually get the fans to turn on.

In general, since I can control the upper slats by using the Auto switch, I just mask the lower plastic vent intercooler area. It is a trade-off for climate daily swings and how much heat you really want. And how much you want to mess with the Auto Switch which control the grills and fans to control any over heating risk.

Now that I understand the CRV engine temp managment system, I actually use the Auto switch to cool down the engine even during summer highway driving (and winter when masking on a hot winter day). All I have to to is hit the Auto temp and the Scanguage quickly shows the engine CT1 temps to drop quicly from the 195-205F to around 185F in a minute or so- summer or winter.
 

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Did you notice at what temp the efans turned on......I presume the compressor was off.

A while back, I intentionally let the V idle sitting in the driveway (after driving around/fully warmed up) with the compressor off to see at what coolant temp the efans would come on. After 20 minutes of wasting gas, coolant temp reached 215F, and NO efans. End of experiment/wasting gas......still don’t know at what coolant temp the ‘puter turns the efans on. Dash temp gauge never moved after stopping at 160F.🤷‍♂️

I think we have hijacked the OP’s thread........sorry.
 

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Did you notice at what temp the efans turned on......I presume the compressor was off.

A while back, I intentionally let the V idle sitting in the driveway (after driving around/fully warmed up) with the compressor off to see at what coolant temp the efans would come on. After 20 minutes of wasting gas, coolant temp reached 215F, and NO efans. End of experiment/wasting gas......still don’t know at what coolant temp the ‘puter turns the efans on. Dash temp gauge never moved after stopping at 160F.🤷‍♂️

I think we have hijacked the OP’s thread........sorry.
Same here! With my 09 they just simply would not come on, but when I kick on the AC they both get going so I know they work.
 

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^^^^Exactly.👍
 

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Seems like I read a TSB discussing flushing the heater core and in the TSB it says let the efans cycle twice. How the heck do you get the efans to cycle even once (compressor off), much less twice.🤷‍♂️
 

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I hope to be wise enough when I make my next purchase to ask a service manager, hey, what do you think of this model, this engine, etc. Some may stick with the company line but I think most would think holy cow, someone realizes I know a lot and wants my opinion...someone please remind me in 10 years.
 

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I have recently had the latest update on my 2018 Honda CRV. It involved the installation of an 120v interior heater (DEF), some sort of circulating block heater, changes to the programing and some change that affects how the coolant flows. I find that these changes have improved the drivability of my CRV. With the car plugged in the cab is more comfortable on those cold mornings. It allows me to turn the heat and fan down to low at start up. This results in the engine heating up much more quickly. Operating normally it would take 3 miles to get the car up to operating temp on the gauge. Now the indicator is solidly in the middle of the gauge within 3/4 of a mile. I then turn up the temp and put the heater on auto. It seems to help warming the car up more quickly and comfortably. The oil level also seems to remain about an 1/8" above full. A marked improvement to the 5/8" it ran at originally. I also wonder if this approach helps with the oil dilution problem. After all the quicker the engine achieves operating temperature you would think might reduce the amount of gas making its way in to the crank case.. I am still not happy with Honda but it is an improvement.
 

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Dayum!.......giving you/installing 2 different heater types.....sounds like Honda is bending over backwards. Not sure how Honda could change the coolant flow????
 
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