No heat at idle (long post)

The Gas and Diesel Engines - VQ40De, VK56DE, YD25DDTi, V9X, Transmission, Transfer Case, Oil, Differentials, Axles, Exhaust...

Moderator: volvite

hefeighteen
Posts: 3
Joined: Fri Dec 13, 2013 9:33 pm
Location: United States

No heat at idle (long post)

Postby hefeighteen » Fri Dec 13, 2013 11:31 pm

Hi all, just joined the forum. My wife drives a 2007 SE we bought brand new, now around 105K miles. We've had zero issues with this truck. It's driven us cross country and then some, up and down the mountains more times than I can remember. Daily driven, though no towing, and no off roading. And since it's not mine, it has no mods either.

We haven't had any issues with the trans/coolant contamination either, thankfully. However, since I've been on the forums the last few days for this heat issue, I've already ordered the part to do the mod ASAP.

Anyway, onto my question. My wife normally warms the truck up on cold mornings; it starts cold, gets up to operating temp, at which point the heat gets hot, and by the time she gets out there the cabin is warm. It has worked like this since 2007. All of a sudden this winter the cabin isn't warm when she gets outside. The air blowing out is cool regardless of how long it's been running. Temp gauge is at the normal spot. As soon as she starts driving to work the heat gets warm and it works fine thereafter.

I started with the "burp" method I found online to remove air bubbles. Hand in hand with this I also added coolant, as it was indeed low. Results from this were hotter air when it was hot, but it didn't fix the idle issue.

Next I replaced the cabin air filter, which was definitely dirty. Results were a perceived 100% increase in volume of air out of the vents. However, heat at idle when started from cold was still cold.

Next I drained the coolant, did a flush with a Prestone flush solution, followed by another water only flush, followed by all new coolant fill. This included the run 10 mins, run the heat 10 mins, cool down cycles for each. (I painted the trim on the house during the downtime...) The hope here was if the heater core is/was restricted or blocked that it might clear out. Still didn't fix it.

Today I went out when she started it and sat in the cold with my coffee and watched the temp gauge. It took its time getting to op temp. I gave it some gas to speed the process, and when it settled out I turned the heat on. Cold air. Gave it a few minutes, still cold. Then with my hand in front of the vent I hit the gas up to 2 or 3K RPM and released. Instantly the air got hot. And stayed that way! Interesting data point.

Today I changed the thermostat. Thought I read you had to remove the fan shroud, which took most of my time, but when I came back inside realized the manual didn't say that. Oops. Made it WAY easier to get to the bolts of course, so whatever. Learned how the whole front end comes apart and goes back together! Anyway, I thought maybe the tstat was stuck open. I didn't have a solid case for this, but I wanted to rule it out. Upon removal the old one was in fact closed, and a little corroded under the lower hose where it might have had a very slow leak. Put the new one in and buttoned it all back up. Same results as this morning. Cold air prior to and after op temp. For a while. Then as soon as I hit the gas it got hot.

So...what else can this be? I'm thinking the heater core could still have a blockage or restriction that requires a surge of pump pressure to get the hot water in there. But the coolant that came out looked pretty clean, so corrosion seems unlikely. I'm leaning more toward a valve that is stuck, or a sensor that is waiting for RPM, but I'm not sure if either of those are real things.

One question I do have for you guys (yes a picture will be better, but I'm inside and it's cold out there) is what that pump looking thing is in the hot water line that goes to the heater? If you're looking under the hood, on the driver side there's a hose that comes out from the head and goes aft and up to a round box near the firewall. Another hose comes out the side of this box and then runs behind the engine and into the heater core. There is a wire harness coming out the top of the box. Somewhere I read that this is a booster or auxiliary coolant pump, but I cannot find evidence of this thing ANYWHERE. Seems like a very likely culprit to me. I'm considering removing it and connecting the hoses with a nipple just to see if it fixes the idle problem. Then I'll go about finding a replacement part!

Anyway, any help or suggestions would be great. This is not a life threatening issues, especially since all she has to do is pop outside after it's warm, hit the gas, and go back inside! But I hate when things don't work right...so I want it fixed.

Thanks in advance!
Dan


Heisenberg
Posts: 36
Joined: Fri Feb 22, 2013 6:43 am
Location: North Shore of Superior Eh!

Postby Heisenberg » Sat Dec 14, 2013 2:06 pm

I have pretty much the same issues, so count me in for replies.

H.

martyf250
Posts: 107
Joined: Wed Jul 06, 2011 6:46 am

Postby martyf250 » Mon Dec 16, 2013 7:36 am

same issue as well. started last winter and randomly does it again this winter.

User avatar
disallow
Site Admin
Posts: 2807
Joined: Wed Aug 13, 2008 9:02 am
Location: Winnipeg, Canada

Postby disallow » Mon Dec 16, 2013 7:40 am

Do you have the rear heater? Did you purge those lines of air as well?

skinny2
Sponsored Member
Posts: 1531
Joined: Sat Dec 26, 2009 10:07 pm
Location: BFE, Ohio

Postby skinny2 » Mon Dec 16, 2013 8:16 am

disallow wrote:Do you have the rear heater? Did you purge those lines of air as well?
I haven't seen much talk of this. I rarely get hot air from the rear heat...only after driving for awhile. What's the process for this?

User avatar
disallow
Site Admin
Posts: 2807
Joined: Wed Aug 13, 2008 9:02 am
Location: Winnipeg, Canada

Postby disallow » Mon Dec 16, 2013 8:39 am

its harder to do, but you have to make sure the heat is wide open while you are burping.

If you have consistent problems, I would suspect leaking rear heater lines.

skinny2
Sponsored Member
Posts: 1531
Joined: Sat Dec 26, 2009 10:07 pm
Location: BFE, Ohio

Postby skinny2 » Mon Dec 16, 2013 8:52 am

I burped it this weekend but not sure it did much. Coolant was completely full everywhere (replaced radiator back in April) so I don't suspect leaking anywhere. I replaced whatever coolant blew out the radiator during the burping process but I wasn't running the rear heater. I would think there would be a purge valve somewhere...seems to make more sense than this burping process.

User avatar
disallow
Site Admin
Posts: 2807
Joined: Wed Aug 13, 2008 9:02 am
Location: Winnipeg, Canada

Postby disallow » Mon Dec 16, 2013 8:53 am

pre-06 pathy's apparently have a valve, but I've never used it. Got rid of it after 06 from what I have read. Maybe 07.

User avatar
HLEGuitars
Posts: 22
Joined: Thu Nov 28, 2013 2:50 pm
Location: State College, PA

Re: No heat at idle (long post)

Postby HLEGuitars » Mon Dec 16, 2013 5:54 pm

hefeighteen wrote:
One question I do have for you guys (yes a picture will be better, but I'm inside and it's cold out there) is what that pump looking thing is in the hot water line that goes to the heater? If you're looking under the hood, on the driver side there's a hose that comes out from the head and goes aft and up to a round box near the firewall. Another hose comes out the side of this box and then runs behind the engine and into the heater core. There is a wire harness coming out the top of the box. Somewhere I read that this is a booster or auxiliary coolant pump, but I cannot find evidence of this thing ANYWHERE. Seems like a very likely culprit to me. I'm considering removing it and connecting the hoses with a nipple just to see if it fixes the idle problem. Then I'll go about finding a replacement part!



Thanks in advance!
Dan
that would be the heater pump!

http://pdf.textfiles.com/manuals/AUTOMO ... er/hac.pdf

page 74

NVRDONE
Posts: 159
Joined: Wed May 07, 2008 1:35 pm
Location: seattle

Postby NVRDONE » Tue Dec 17, 2013 9:27 pm

There is a purge valve on the right side of the fire wall
It really helps to have the rear heat on and the front end elevated when you burp these cooling. Systems

User avatar
smj999smj
Site Admin
Posts: 5812
Joined: Sun Jan 22, 2012 11:13 pm
Location: Prospect, VA

Postby smj999smj » Tue Dec 17, 2013 10:32 pm

The heater pump is a dealer only part to my knowledge.

User avatar
disallow
Site Admin
Posts: 2807
Joined: Wed Aug 13, 2008 9:02 am
Location: Winnipeg, Canada

Postby disallow » Wed Dec 18, 2013 7:14 am

what does that mean, dealer only? Special tools required? I'm sure the dealer would like all parts to be 'dealer only' LOL.

What does the heat pump actually do? Augment the engine coolant pressure to the rear lines? Didn't know the pathy had that, but I guess it would make sense.

User avatar
smj999smj
Site Admin
Posts: 5812
Joined: Sun Jan 22, 2012 11:13 pm
Location: Prospect, VA

Postby smj999smj » Wed Dec 18, 2013 5:39 pm

By "dealer only" I mean that the part is likely not available on the aftermarket and would have to be obtained from a Nissan dealer. Originally, I though it was just an electric heater cock, but since finding out the Nissan calls it a "heater pump," it make me think that it is actually a small electric pump used to push the coolant through the rear heater. The heater pump is mounted to the firewall, on the driver's side of the engine, with an electrical harness to it and mounted between two 5/8" heater hoses. It's not hard to find.

hefeighteen
Posts: 3
Joined: Fri Dec 13, 2013 9:33 pm
Location: United States

Postby hefeighteen » Tue Dec 31, 2013 8:02 pm

Update to the original post:

The system seems to be working normally now. I guess the thermostat fixed it, as that was the last thing I changed, but it's not a very convincing argument. As long as it works, right?

Meantime I went ahead and did the transmission cooler bypass, completely unrelated. Got the advice from this forum, so thanks for that. Peace of mind now complete.

In response to HLEGuitars' post regarding the heater pump, thanks for identifying that. The page in the FSM is awesome! I will run their diagnostic test next chance I get. The temp differential would be the only condition we'd ever meet, as we don't use the heat on full blast, but a 60 degree diff is easy on a cold morning. The absence of that pump all of a sudden could certainly cause this symptom, so I'm anxious to confirm or deny that piece.

Incidentally, there are a considerable number of posts out there on the web about Pathfinders not having heat at idle, and not a single one I have read mentions the heater pump. I don't understand why. Many of them are on those "answer" sites where professionals get paid to answer questions. Almost across the board they recommend burping and flush and fills, and don't mention that pump at all. Am I the only one that thinks this a large oversight?

Thanks!

Dan

User avatar
DreamerzCC
Posts: 32
Joined: Thu Mar 24, 2011 7:28 am
Location: Hoover, Alabama

Postby DreamerzCC » Wed Jan 08, 2014 1:25 pm

Our Pathy heats on idle in the mornings but my Xterra will not until you start driving. Noticed it when it started to get cold here. It just blows like the A/C is on. Mornings its ok because I am in a garage but idling after its been parked at the airport for a week or the mall for a few hours I get no heat until I start driving.


Return to “R51 Engine, Driveline and Powertrain”