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Discussion Starter #1
Heater blows cold air.

Selector switch works, blows cold out of where ever i tell it to blow hot air.

Fan speed works, blows cold air at various velocities out of duct work.

This is second time this has happened to me; always when i'm on a long trip; freezing my arse off all day.

Last time this happened they told me they could not replicate the problem; yet it mysteriously worked fine after that.

I've tried taking radiator cap off while running to let air out; i unbolted the water cutout valve and lowered it below the radiator cap level. Still nothing but cold air. Hose before valve is warm, hose after valve is cold. Gonna check for voltage to valve in a sec.


Sidenote:
WTF: everybody knows the radiator cap is supposed to be the highest point of any vehicular water system; so Nissan puts these heater hoses a good 8" above the cap... couldn't design a better air bubble catcher if they tried.

I'm ready to sell this titan!

Can't be the water isn't hot enough... it's plenty hot. Can't be the water pump isn't pumping enough water (i cranked that mofo to redline for quite a while cuz i was mad and cold).

Any idears?
 

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Mine had a bad heater control mixing switch.
So they said.
 

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Air pocket it sounds line. My Titan did the same thing. Heater worked great until I removed the radiator cap to replace a hose clam right there. Then I had overheating issues. Yesturday I took it for a long drive (about 100 miles) and truck didn't overheat. I even sat infront of a house for an hour and it didn't overheat. Got home, and later that night my girl wanted to go shopping (I thought it was for bras and panties..it was for jeans..go figure) so kinda cold last night, mild hot air. Then I noticed my temp guage went up to the limp mode line, then instantly shot back down, and the air got a lil warmer, but not much. And bleeding these trucks is a PITA. So watch your temp guage. If it spikes, you got a big air pocket. If not, sounds like just a small stubbon air pocket in your heater lines.
 

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Discussion Starter #4 (Edited)
Found the problem.

Turns out Volkswagen engineers designed the water cutout valve: it is Waaaay over enginneered.

Why the frick does a simple water valve require two worm gears????

Well, when i was removing the 3-screw cover of the valve i noticed antifreeze in the bottom screw hole; and then found even more inside the cover. So i figure the bushing/bearing or whatever invovled in this whizz-a-ma-gig are corroded.

Turns out that the little motor doesn't have enough torque to turn: 1: a slightly corroded valve mechanism 2: two worm gears 3: a bunch of plastic crap.

IDK why they engineered this valve so retardedly.

Also there are no end switches; so the valve never knows it's actual location.
The motor runs for approximately 20 seconds on a change of temperature call... so this could make it working hit or miss; if 20 seconds doesn't move it.
The gears are very soft plastic so i can imagine this thing skips gears quite often.

I will put it back together (with a healthy dose of antifreeze inside cover) and taking it in for warranty repair.

I wonder how much this part costs.?.


OH and fyi: if you're ever stuck in a cold climate with no heat: remove three little screws, pop out the little worm gear stick, turn the black mechanism gear fully counter clock wise (about 90 degrees or so) and you will have full heat.

BTW: The a/c seems to work just fine with this manually opened, it still uses the air flap to divert cold/hot air as needed... so i don't see why this valve is really even necessary (except perhaps to allow faster engine warm up).
 

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OMG!! i taught i was the only one with this problem... i posted this up a while back and didnt get a answer so i took it to the dealer and they couldnt find the problem, but they did drive my truck for 100+ miles.. i was pissed.. hey where is this 3-screw cover of the valve you talking about.. iam new to nissan titans that would help me out alot thanks...
 

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Discussion Starter #6
OMG!! i taught i was the only one with this problem... i posted this up a while back and didnt get a answer so i took it to the dealer and they couldnt find the problem, but they did drive my truck for 100+ miles.. i was pissed.. hey where is this 3-screw cover of the valve you talking about.. iam new to nissan titans that would help me out alot thanks...
Under the hood, above the engine, centered but slightly to the passenger side of the truck. It has one nut/stud holding it to the firewall. Remove the nut on the stud so you can manipulate it. There are 3 screws that hold the cover on the assembly (the cover also acts to hold the double wormgear stick in place). If you remove the bottom most screw, and see any liquid/antifreeze (even 1 drop) i bet your valve is screwed.

You can probably remove the cover without unbolting it from the firewall with the right screwdriver.

GL
 

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I'm new in this forum, I have the same problem with my Titan, it seems that the only time the heater works is when it wants to work. Sometimes I think it's the heater core but I'm not sure, any suggestions? Everything else works perfect in the truck such as the A/C, thanks.
 

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It's summer.... Worry about it in October.
 

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I know it's summer lol, but it's just that I been having the same problem since last year. I just like having my titan in top shape, might not fix it right now.....but it'll be good to have it working by next winter you know........
 

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2007 Titan SE 4X4. Heater stopped working a couple of weeks ago and it's just started to get cold here in BC, Canada.... 3 degrees C yesterday.

I tried the possible air bubble trick and had no luck. So I cracked open the heater valve and the bottom of the casing had some coolant in. Popped out the worm gearstick, turned the top gear wheel counter-clockwise, just over half way, put it all back together and now I have heat.:)

Both hoses on either side of the heater valve are hot. Before, just the one side hose was barely warm.

It doesn't seem to have caused any hiccups anywhere else.... the dial works from cold to hot, AC is ok. Took me 15mins.

I put in a new Variable Blower Control (VBC) while I was at it. Previously, no matter what the dial setting, it blew full blast. That's fixed now too. $70 CDN for the part from the dealer in Vancouver. Easy 5 minute job (it's located under the glove box).

So I'm hoping I'm good to go. Thanks titan_dork for the info and instructions. Seems like this is a common problem. I'll keep my eye on it through winter. Hopefully, this fix will work and won't throw up any issues.
 

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Discussion Starter #11
2007 Titan SE 4X4. Heater stopped working a couple of weeks ago and it's just started to get cold here in BC, Canada.... 3 degrees C yesterday.

I tried the possible air bubble trick and had no luck. So I cracked open the heater valve and the bottom of the casing had some coolant in. Popped out the worm gearstick, turned the top gear wheel counter-clockwise, just over half way, put it all back together and now I have heat.:)

Both hoses on either side of the heater valve are hot. Before, just the one side hose was barely warm.

It doesn't seem to have caused any hiccups anywhere else.... the dial works from cold to hot, AC is ok. Took me 15mins.

I put in a new Variable Blower Control (VBC) while I was at it. Previously, no matter what the dial setting, it blew full blast. That's fixed now too. $70 CDN for the part from the dealer in Vancouver. Easy 5 minute job (it's located under the glove box).

So I'm hoping I'm good to go. Thanks titan_dork for the info and instructions. Seems like this is a common problem. I'll keep my eye on it through winter. Hopefully, this fix will work and won't throw up any issues.
Yup.

You likely won't notice any issue until you need to run a/c again (really hot outside), then it won't blow as cold on 'regular' but will blow plenty cold when set to 'max'. And vent will always be warmer than usual by a bit.

HAHA, i still need to replace mine.
Been having too much fun with my motorcycle to care though.
New one is hanging on the shed door for months now.
 

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I have a Nissan titan 2006 I just fix my heater, I buy this part #27743ZH00A, I had to remove all the dashboard to get to where the part is located, I install the new part, and before I install the dashboard back on , I connect the air conditioning and heating control panel, to test!!!, everything works fine, but when I turned the air conditioning on , the door actuator bracket, moves as if it were to move out of the track, then the only solution is not bring the temperature control knob to the lowest, you need to go 2 clicks before , and the actuator will not come off the track and the heater will work fine , this door actuator is badly designed and should be repaired by the dealer, and being redesigned, this should be a recall, by Nissan.
 

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I have a Nissan titan 2006 I just fix my heater, I buy this part #27743ZH00A, I had to remove all the dashboard to get to where the part is located, I install the new part, and before I install the dashboard back on , I connect the air conditioning and heating control panel, to test!!!, everything works fine, but when I turned the air conditioning on , the door actuator bracket, moves as if it were to move out of the track, then the only solution is not bring the temperature control knob to the lowest, you need to go 2 clicks before , and the actuator will not come off the track and the heater will work fine , this door actuator is badly designed and should be repaired by the dealer, and being redesigned, this should be a recall, by Nissan.

The dealer charge $675 labor only, and the part cost $32 Im in Tulsa Oklahoma, if you have a nissan titan with the same problem I can fix it for $400 labor you need to buy the part my number is 918-808-4247 thanks
 

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So I was having trouble with my heat not working at all. I would crank it up to 90 degrees and it would be colder than it was outside. I took out the 3 screws and the cover of this valve and pulled it off. Guess what I'm guessing this is my problem. The gears were actually laying down inside the cover in pieces......
 

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I had the same heat not working on my 2006 Titan. I took it to a shop who replaced the actuator door and THOUGHT that they had fixed the problem. The heat worked for about 2 months. A few months ago(when the weather turned cold again) My heat would not work..... again. Took the truck to another mechanic and they replaced the thermostat. That did not fix it. I took it back to the second shop and they kept the truck for a week and could not figure out the problem. I was about to go to the dreaded dealership, where I know I would be robbed. But first I checked this forum and found the answer. The solution that worked is to NOT turned the temperature control knob to the lowest setting, you need to turn it only 2 clicks into the red and the actuator will not come off the track and the heater will work FINE. I am sooooooooooo freakin happy I could :redblob":redblob" Thank You Casanova from Tulsa Oklahoma!!! You saved me hundreds of $$$ and a lot of STRESS!
 

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OK so not sure whats happened except the air bubble theory. I just replaced the o-ring on the oil cooler on my 04'. I had completely removed the cooler and left the coolant hoses hanging for an hour. Now my heater doesn't work. Anybody have some suggestions?? Im about at my breaking point with these trucks. I guess it wouldn't be so bad if I only had one, but Ive got two and once I fix something on one the other has a problem.
178,000 miles on the 04' and it still runs like a champ, its just the little things...
 

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Under the hood, above the engine, centered but slightly to the passenger side of the truck. It has one nut/stud holding it to the firewall. Remove the nut on the stud so you can manipulate it. There are 3 screws that hold the cover on the assembly (the cover also acts to hold the double wormgear stick in place). If you remove the bottom most screw, and see any liquid/antifreeze (even 1 drop) i bet your valve is screwed.

You can probably remove the cover without unbolting it from the firewall with the right screwdriver.

GL
Had the same problem you have it was the control box as listed above . Dealer replaced it and works fine now :) it was covered under my extended warranty !
 

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So you don't think it has anything to do with disconnecting the coolant lines from the oil cooler? I just did this 2 days ago and the truck has sat until this evening. I think its too coincidental...
 
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