Subaru B9 Tribeca SUV Forum banner

Heater issue-passenger has no heat 07 TriLtd

66K views 63 replies 30 participants last post by  Wags 
#1 ·
I am looking for a few Suggestions on what may fix a heater issue i have recently been having. On the driver side, the heater works well in all modes (auto/manual in all combinations). The passenger side, however, blows relatively colder air than the driver side. With both temps at 85, the driver side is fine, but the passenger facing body and feet vents, as well as the defrost vents blow cold. Because I am now out of the warranty period and would like to avoid the excessive charges at the dealership, any ideas on what may be the culprit?
 
#3 ·
Yes, I am over the mileage (48k). I was recently charged on an electrical issue which i thought would be a warranty repair, and would assume i would be tagged again for something like this.
Do you suppose a vacuum leak in the engine may cause this or a leak in the heating system itself?
Thanks!
 
#5 ·
Sounds like a vent door is stuck. Your engine is generating all the heat necessary to bake the cabin, but if a vacuum door is stuck closed (or partly closed), you'll feel cool outside vent air seeping around it.

Could be a problem with the door itself, the servo that opens it, the wires that power/control servo, or in the HVAC panel itself. I'd troubleshoot in that order.
 
#6 ·
jimbo said:
Sounds like a vent door is stuck. Your engine is generating all the heat necessary to bake the cabin, but if a vacuum door is stuck closed (or partly closed), you'll feel cool outside vent air seeping around it.

Could be a problem with the door itself, the servo that opens it, the wires that power/control servo, or in the HVAC panel itself. I'd troubleshoot in that order.
Thanks. Been there done that and all was good, but good advise.
 
#7 ·
I would have gone with jimbo's guess too that it's a "zone" door getting stuck since your getting heat on the other side.:Dunno:
 
#8 ·
I found a recall for certain VIN# 2006 Tribecas (Service program WWY-09)and some other models that had issues with chlorine in the coolant creating corrosion issues in heater core. Involves a good flushing of the heater core.
http://www.scoobymods.com/my_06_coolant_flush-t6634.html?t=6634 Thanks Peaty :)
The coolant system may have flow issues to and in the core. I'll update after I flush it.

Hopefully this info will help others having the same issue.
 
#11 ·
Same heater problem

Hi, I have an '06 as well, and I am having the exact same heater problem. I also have the problem where I need to turn up the heat on the driver's side to about 75 to be comfortable (the passenger side needs to be at about 85). Any solutions yet, or handy tips? I am not very mechanically inclined, but I will probably try to solve the problem myself anyway, as I am also very cheap. Thanks for any help.
 
#12 ·
Same issue passenger heat doesn't work

Hi, I just got my car back from my independent shop and they threw in the towel. They tried to replace the motor that operates the vents on the passenger side but figured out something was binding up the motor. So they told me I would have to take it to the dealer. Before I do that I thought I would check with you folks and see if anyone had resolved this issue. Appreciate any feedback. Thanks.
 
#13 ·
Kilbu said:
something was binding up the motor
"Something"? Still sounds a little vague to me. If I were in your shoes, I'd think about whether to commit to investing money and time in pulling your dash apart to fix it, or whether to just trade her in.

There's not a good chance this problem would be discovered in the trade once-over a dealer would give it...
 
#14 ·
Concerned

That idea definitely crossed my mind! My independent shop said the dealership would charge me $500-700 just to get into it. Then who knows how much the rest of the labor and parts will add up too. I could be creeping up on $2000. My biggest fear is going through this for the passenger side then the driver side will go. It's too bad because we absolutely love the vehicle. Thanks for your feedback jimbo.
 
#15 ·
i had the same problem with my tribeca. the heater core was plugged up with the factory coolant that was in it, i guess it caused alot of corosion and plugged. anyways i tried flushing it about 4 times and put some treatment into it, but inthe end i had to replace the heater core. the core was about $150cdn and i had a local mechanic do it for about $500. now everything is working great
 
#16 ·
Interesting that a lot of folks are talking about vacuum controls on the heater/AC. All of the Tribeca's controls are electric servos. It also doesn't make sense that the heater core is the problem, as the heater core serves both sides not just one. This is a fairly common problem with Tribeca's, mine, too.
The diagnostic routines say everything is OK, and if anything doesn't work replace the AC ECU. Wasted almost $300 on that. Pulling the servos is fairly easy, and all of the doors on the right side seem to work OK. I suspect that with those folks that had someone replace the heater core the mechanic found the real problem and fixed it gratis. So, I'm still stumped. It would be nice if someone found the real problem and reported back. I don't have a grand laying around for the dealer to play with my car.
 
#17 ·
Thought I would chime in with my experience. Same issue no warm air for passenger side. I pulled the inlet/outlet pipes off connected them together so I minimized coolant loss. I then covered starter and other electronics after disconnecting the negative terminal. Next step I took my compressor and stuck in the inlet (upper) side and kept going til nothing but air was passing though. I then grabbed a garden hose with a nozzle and put pressurized water through the core for 30seconds then blast more compressed air til dry. I did this a couple times then reconnected all lines. Burp the system and you should be good to go. Hope this helps.
 
#18 ·
Heater core!!!

We had an '06 that had the same problem. At 50,000 with a Subi service contract brought to dealer. They put a blend motor for pass side on. not fixed. Brought it back, they had car for 1 1/2 weeks and had nearly 25 hours invested in it. Had Subaru tech support invloved and it turned out to be a heater core.

I am a general manager for an independant repair facility so I tested all the basic operations including moror and door movements but was unable to get any heat out of the passenger side. So off to the dealer which initially put a blend motor in without testing first.

We now have a '08 with 92,000 and have no heater issues yet.
 
#20 ·
dan04103 said:
Thought I would chime in with my experience. Same issue no warm air for passenger side. I pulled the inlet/outlet pipes off connected them together so I minimized coolant loss. I then covered starter and other electronics after disconnecting the negative terminal. Next step I took my compressor and stuck in the inlet (upper) side and kept going til nothing but air was passing though. I then grabbed a garden hose with a nozzle and put pressurized water through the core for 30seconds then blast more compressed air til dry. I did this a couple times then reconnected all lines. Burp the system and you should be good to go. Hope this helps.
Even though I did not believe the problem could be related to the heater core as there is only one core and the core is not divided at all, I tried what Dan suggested. FAIL! I put it all together and no change. Right side has no heat. What I've been doing is set mode to feet and defrost, turn off A/C, and set recirculate cabin air.
 
#21 ·
Just incase anyone breezes over this thread, I had this same issue and it was heater core related, see the pics in this thread: http://www.sb9t.com/forums/showthread.php?t=2593

The HVAC box is basically split into 2 parts internally. (Dual climate control remember....)
the heater core slides in a slot like a cartridge and covers both sides.
if half of the core is blocked it wont receive enough fluid to heat the air passing through it. From my case it was the far side of the core which serves the passenger side of the system. I would suppose if it was the side of the core closest to the feeder pipes, neither driver OR passenger would receive warm air.
 
#22 · (Edited)
The first thing I have to say about this thread is that my thinking was completely wrong and I was totally wrong so please disregard everything I posted previously on this subject.
That being said, I did find the problem and fixed it without taking the whole dash and interior apart. Thanks to member "nuke" for setting me on the right track
Before getting into the fix, I want to mention that the Tribeca is sold in right hand drive countries so the problem does not always appear on the passenger side. This repair was done on a US model Tribeca.
What I did:
I bought a new heater core, about $US 130.
Disconnect the ground cable from the battery.
Remove the panel under the steering column and the forward plastic one on the side of the console.
I removed the throttle and the control box above it, then tied the wires up and to the Left.
Take off the cover that covers the heater (coolant) pipes.
Drain a gallon of coolant from the radiator.
Pull the plenum off the top of the engine to gain access to the heater hoses and disconnect them.
Secure one end of a large rag around the lower pipe after removing the hoses, and blow compressed air in the upper pipe. This will help keep coolant out of the interior.
Back inside, I used an air powered 4" cutoff disc to cut both pipes.
Slide the heater core out.
Cut and debur the new heater core to match the old one. Be careful to keep aluminum chips from getting into the core.
Debur the new new pipes and replace the old ones still in the car. There is one screw that secures the clamp.
Slide the new core in.
Connect the pipes using new heater hose. I got the hose and clamps at NAPA.
Put the stuff in the engine compartment back together.
Fill the cooling system with new coolant, put the interior back together and connect the battery.
Total time for me was about 4 hours. If you are not 70 years old you could probably do it faster. Not great pictures, but you'll get the idea. My bride is happy about having heat on her side. BTW. Check the coolant level with the engine cool after each of the next three heat cycles. By then it should be completely full. If not, start looking for leaks.
 

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#23 ·
Thank you Jim. This has to be one of most valuable posts on SB9T.
Do you think it would have been possible to run the hoses from the sawed-off pipes all the way into the engine compartment and connect there, or would the bends be too tight? FWIW, the manual my Dodge minivan shows a very similar set-up for the heater core, but the pipes are separate and attach to the core with bolt-on flanges. On the other hand, replacing AC evaporator on the van positively requires removing the instrument panel, which is not the case for Tribeca.
 
#25 ·
I just registered to see if I could find a solution for the same problem in my wifes Tribeca... Just curious if it can cause overheating? I already pulled the engine and put new HG, pump, resealed it.. It was a PITA to bleed and I wonder if the plugged heater core issue could cause it to have engine cooling issues..

Good info on putting the core in that way! I will do ours like that!

Gary
 
#26 ·
Gary,
I doubt that the heater core would cause overheating, but if you read the whole thread you know I can be wrong at times. I have not really studied the coolant flow on this engine.
BTW, my experience with air in coolant systems is that with a proper functioning coolant recovery system, by the time you have completed 3 thermal cycles the air will be gone. A thermal cycle is cold to normal operating temperature and back to cold. I have seen folks anguish over this problem and try all kinds of things including adding holes in thermostats. What I noticed is that OEMs don't do anything special. It is important to get as much coolant as possible in the system before starting the engine. That is why some systems have two radiator caps, one at the highest point in the system. When I work on a cooling system I always run at least one thermal cycle watching the temperature until the engine is up to operating temperature before shutting it off.
If you started this adventure because of overheating, you will want to check to see that the radiator tubes have not expanded and now shut off the air flow. This is a common problem with OEM aluminum radiators once they have been overheated.
 
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