# Very odd car behaviour **URL:** \ **Category:** Factual Questions\ **Created:** [December 15, 2018, 6:03pm UTC](https://boards.straightdope.com/t/very-odd-car-behaviour/826186 "2018-12-15T18:03:32Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\ **Post date:** [December 15, 2018, 6:03pm UTC](https://boards.straightdope.com/t/very-odd-car-behaviour/826186/1 "2018-12-15T18:03:32Z")
I think GQ is right for this. Ok. 2006 Nissan Pathfinder 204,000 miles. Good vehicle all around. Friday, I put some different cd’s into the OME Bose stereo. Tested it and it worked fine and as expected. Then left for 100 mile drive. I turned on the stereo during the trip, and everything worked, except no sound came out through CD or FM. All display working properly. I stopped and started car, and it started working again. :shrug: Now it gets weird. After car sits for 3 hours, I turned on the heat to Automatic. The heat only blows through vents when engine is up to temp (when on ‘Auto’ this is expected and normal). Engine comes up to temp, the fans start pushing air, but no heat. Drive 5 miles and fiddled with controls (turn auto off/on) and still no heat. Got to destination, let car sit for 5 minutes. Start car up and heat worked. It happened again this morning. Warm up car. No heat but fans working. Stop car for 15 minutes and heat works fine. Stereo is fine now too. I know. Totally unrelated things with stereo and heat. But, it seems the fix is a restart of the car. Odd. Computer problem? Or coincidence. And why would the heat be that way? Is there a valve that opens and closes for coolant to run through the heater core? That would be a new one on me. But can’t think of any other explanation. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [December 15, 2018, 6:19pm UTC](https://boards.straightdope.com/t/very-odd-car-behaviour/826186/2 "2018-12-15T18:19:58Z")
> [@enipla](#): > > I think GQ is right for this. > > Ok. 2006 Nissan Pathfinder 204,000 miles. Good vehicle all around. > > Friday, I put some different cd’s into the OME Bose stereo. Tested it and it worked fine and as expected. Then left for 100 mile drive. > > I turned on the stereo during the trip, and everything worked, except no sound came out through CD or FM. All display working properly. I stopped and started car, and it started working again. :shrug: > > Now it gets weird. > > After car sits for 3 hours, I turned on the heat to Automatic. The heat only blows through vents when engine is up to temp (when on ‘Auto’ this is expected and normal). Engine comes up to temp, the fans start pushing air, but no heat. Drive 5 miles and fiddled with controls (turn auto off/on) and still no heat. > > Got to destination, let car sit for 5 minutes. Start car up and heat worked. > > It happened again this morning. Warm up car. No heat but fans working. Stop car for 15 minutes and heat works fine. Stereo is fine now too. > > I know. Totally unrelated things with stereo and heat. But, it seems the fix is a restart of the car. Odd. > > Computer problem? Or coincidence. WAG is there’s a wiring issue somewhere in the dash. perhaps communication between modules is being lost. > [@](#): > > And why would the heat be that way? Is there a valve that opens and closes for coolant to run through the heater core? That would be a new one on me. But can’t think of any other explanation. probably not. there are a couple of “blend doors” in the HVAC manifold which control the mixing of hot and cold air, and control which “zones” it delivers air to. If the system is commanding heat and the air coming out is cold, then likely the blend door is not being actuated. ---
**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\ **Post date:** [December 15, 2018, 7:19pm UTC](https://boards.straightdope.com/t/very-odd-car-behaviour/826186/3 "2018-12-15T19:19:07Z")
> [@jz78817](#): > > WAG is there’s a wiring issue somewhere in the dash. perhaps communication between modules is being lost. > > probably not. there are a couple of “blend doors” in the HVAC manifold which control the mixing of hot and cold air, and control which “zones” it delivers air to. If the system is commanding heat and the air coming out is cold, then likely the blend door is not being actuated. Thanks. I’m also wondering if it’s a wiring issue. The car gets knocked around a bit on gravel roads. And has plenty of miles on it. Heh. Blend door. That makes sense. Thanks. ---
**Author:** ![Gatopescado](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gatopescado/32/5711_2.png) [@Gatopescado](https://boards.straightdope.com/u/Gatopescado)\ **Post date:** [December 15, 2018, 7:28pm UTC](https://boards.straightdope.com/t/very-odd-car-behaviour/826186/4 "2018-12-15T19:28:45Z")
> [@enipla](#): > > Now it gets weird. 😃 I’ve got a BMW that developed two distinct, completely unrelated faults that would come and go intermittently (one being the stereo) that eventually made me question my own sanity. Love that car, and still own it. ---
**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\ **Post date:** [December 15, 2018, 8:07pm UTC](https://boards.straightdope.com/t/very-odd-car-behaviour/826186/5 "2018-12-15T20:07:16Z")
> [@Gatopescado](#): > > 😃 > > I’ve got a BMW that developed two distinct, completely unrelated faults that would come and go intermittently (one being the stereo) that eventually made me question my own sanity. > > Love that car, and still own it. Wana buy a Pathfinder? ---
**Author:** ![mind\_the\_gap](https://avatars.discourse-cdn.com/v4/letter/m/ea666f/32.png) [@mind\_the\_gap](https://boards.straightdope.com/u/mind_the_gap)\ **Post date:** [December 15, 2018, 8:17pm UTC](https://boards.straightdope.com/t/very-odd-car-behaviour/826186/6 "2018-12-15T20:17:26Z")
If it was a British car, I’d say you let some of the smoke out of the wires. I had a Sunbeam Alpine when I was a kid, and if the headlights were on and you hit a harsh bump, the lights would go out, the wipers would cycle twice and the lights would go back on. Very entertaining at night on a winding road. As you describe the issues, they seem unrelated. If it were me, I’d start with cleaning contacts for relays and fuses since Gremlins can lurk there. It’s also possible that the blend doors may have leaking vacuum hoses or connections if they’re controlled that way rather than electrical actuators. If you can get the service manual that may she’d some light on the situation. ---
**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\ **Post date:** [December 15, 2018, 9:32pm UTC](https://boards.straightdope.com/t/very-odd-car-behaviour/826186/7 "2018-12-15T21:32:03Z")
> [@mind\_the\_gap](#): > > If it was a British car, I’d say you let some of the smoke out of the wires. I had a Sunbeam Alpine when I was a kid, and if the headlights were on and you hit a harsh bump, the lights would go out, the wipers would cycle twice and the lights would go back on. Very entertaining at night on a winding road. As you describe the issues, they seem unrelated. If it were me, I’d start with cleaning contacts for relays and fuses since Gremlins can lurk there. It’s also possible that the blend doors may have leaking vacuum hoses or connections if they’re controlled that way rather than electrical actuators. If you can get the service manual that may she’d some light on the situation. Re British cars - [Joe Lucus, the Prince of Darkness](https://jalopnik.com/399791/joe-lucas-prince-of-darkness-british-electrical-system-jokes) Have a cousin that had a Sunbeam and a Spitfire. Now he’s working on a Lotus. ---
**Author:** ![mind\_the\_gap](https://avatars.discourse-cdn.com/v4/letter/m/ea666f/32.png) [@mind\_the\_gap](https://boards.straightdope.com/u/mind_the_gap)\ **Post date:** [December 15, 2018, 10:27pm UTC](https://boards.straightdope.com/t/very-odd-car-behaviour/826186/8 "2018-12-15T22:27:12Z")
> [@enipla](#): > > Re British cars - > > [Joe Lucus, the Prince of Darkness](https://jalopnik.com/399791/joe-lucas-prince-of-darkness-british-electrical-system-jokes) > > Have a cousin that had a Sunbeam and a Spitfire. Now he’s working on a Lotus. The man sounds like a masochist. JK, always loved my Brit cars. There is a chap selling a replacement smoke kit. Too bad the OP’s car is Japanese, I don’t think they’ve reached that level of support yet.🙂 ---
**Author:** ![mind\_the\_gap](https://avatars.discourse-cdn.com/v4/letter/m/ea666f/32.png) [@mind\_the\_gap](https://boards.straightdope.com/u/mind_the_gap)\ **Post date:** [December 15, 2018, 10:33pm UTC](https://boards.straightdope.com/t/very-odd-car-behaviour/826186/9 "2018-12-15T22:33:01Z")
Yessir, that’s the ticket! ---
**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\ **Post date:** [December 16, 2018, 6:01am UTC](https://boards.straightdope.com/t/very-odd-car-behaviour/826186/10 "2018-12-16T06:01:33Z")
All right then. I have been trying to talk myself into keeping my Pathfinder for a few more years. But I don’t think it’s gonna work out. We will have to part ways. I must have a car that will take care of me in the Rocky mountain winters. 204,000 miles. We have had a good run. It’s time. Too many people depend on me to have to depend on a car that would best serve someone else. Next up - Toyota 4-Runner TRD Off-Road Premium. Yes I like some bells and whistles. Body on frame (a dying breed I know). When you have to hook a 10,000lb winch on a ‘car’ to get it un-stuck, I like the body on frame. i’d rather not remember those times, and hope to have fewer of them. The 4-Runner also has a locking rear differential that would have saved me in too many times that I would like to remember. ~enipla - I used to go off-roading for fun. Now, I just want to make sure to get home. It’s cool though. And the summers are worth it. 84"'s of snow so far this year. Seven feet. March is when we REALLY get snow. ---
**Author:** ![mixdenny](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mixdenny/32/2962_2.png) [@mixdenny](https://boards.straightdope.com/u/mixdenny)\ **Post date:** [December 16, 2018, 6:23am UTC](https://boards.straightdope.com/t/very-odd-car-behaviour/826186/11 "2018-12-16T06:23:05Z")
> [@enipla](#): > > And why would the heat be that way? Is there a valve that opens and closes for coolant to run through the heater core? That would be a new one on me. But can’t think of any other explanation. Some cars have just such a system. My BMW 5 series had not only valves for the coolant flow, but a variable speed pump that pumped hot water to either the passenger or diver sides depending on what was needed. [![](https://img.youtube.com/vi/SJe-WANmlTs/maxresdefault.jpg "Rebuilding Heater Valve in my E34 525") ](https://www.youtube.com/watch?v=SJe-WANmlTs) Dennis ---
**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\ **Post date:** [December 16, 2018, 1:56pm UTC](https://boards.straightdope.com/t/very-odd-car-behaviour/826186/12 "2018-12-16T13:56:39Z")
> [@mixdenny](#): > > Some cars have just such a system. My BMW 5 series had not only valves for the coolant flow, but a variable speed pump that pumped hot water to either the passenger or diver sides depending on what was needed. > > [https://www.youtube.com/watch?v=SJe-WANmlTs](https://www.youtube.com/watch?v=SJe-WANmlTs) > > Dennis Two heater cores? ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [December 16, 2018, 3:06pm UTC](https://boards.straightdope.com/t/very-odd-car-behaviour/826186/13 "2018-12-16T15:06:14Z")
If you have steering wheel controls the wires, though a wore coil, could be going out. I had this in a Nissan Rogue, though there were no ventilation controls (or problem with the HVAC) on the steering wheel controls. ---
**Author:** ![HoneyBadgerDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/honeybadgerdc/32/1033_2.png) [@HoneyBadgerDC](https://boards.straightdope.com/u/HoneyBadgerDC)\ **Post date:** [December 16, 2018, 5:14pm UTC](https://boards.straightdope.com/t/very-odd-car-behaviour/826186/14 "2018-12-16T17:14:33Z")
Your heating problem could be electrical or a heater control valve or it might just be a little low on coolant. The most common problem I saw when heating was intermittent was low on coolant. ---
**Author:** ![mixdenny](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mixdenny/32/2962_2.png) [@mixdenny](https://boards.straightdope.com/u/mixdenny)\ **Post date:** [December 17, 2018, 1:15am UTC](https://boards.straightdope.com/t/very-odd-car-behaviour/826186/15 "2018-12-17T01:15:48Z")
> [@enipla](#): > > Two heater cores? Actually one wide core with an inlet on each end and a common center return. So three pipes: > **[BMW Heater Core 64118351171 – Behr 351312771 Behr Hella Service 351312771](https://eeuroparts.com/product/behr-hella-service/351312771)** > > OEM and Genuine parts at the best prices. BMW Heater Core 64118351171 - Behr 351312771 guaranteed fit and fast shipping Dennis