Heater blows cold till temp gauge at H

[howie]

Looked through the other "heater blows cold" threads and most people seem to have a slightly different symptom. I'll try to explain what's happening and trust you'll redirect me so we can figure this one out. See UPDATE at bottom of post too.

1. It's cold in Minnesota right now, as expected.
2. I start driving, temp gauge in dash is at C for several minutes, as expected.
3. Heat gauge in dash starts rising to the middle, highway or street driving, as expected.
4. Heat is on 'AUTO' setting at 70 degrees.
5. Slowly the blower starts blowing cold air at full (4 fans in display) on my feet -- not pleasant.
6. I hit the off button for a while.
7. Temp gauge starts rising past middle towards high.
8. I turn the heat back on to 'AUTO' after a few more minutes, expecting heat by now -- still cold.
9. Turn heat back off.
10. Temp gauge starts rising to H.
11. Turn heat back on to 'AUTO'. Heat starts flowing normally, no matter whether I'm driving or idling, streets or highway. Heat is very hot, seems hotter than 70 degrees, but of course I'm still bundled up.
12. Heat keeps working "normally" after this, consistently, but the temp gauge fluctuates from "too hot" to "very hot"... I get worried I'm doing damage to the engine.

This had been going on for the last 3-4 days so I made an appointment and finally took time to write this post.



UPDATE - The Midas guys say a coolant flush will fix it. So I'll drop the $80 or so (since I don't have time or a warm garage to learn this myself tonight). I'll be able to reply later about whether it fixed it or not. They say it was a coolant problem, there's no leaks, they are bleeding out the air bubbles and flushing it, they think this will fix it. I asked if they'd flush both the cool and heat directions (from reading other posts) and they said they always do that here. The owner-guy says he loves Nissan / Infinity and always buys them.


Hope this helps someone else who might have a similar problem. I guess it looks like it might have the same solution as some of the other posts even though the symptom was slightly different.

Thanks for a great forum!

[CanuckQx4]

Definetely dont drive a vehicle indicating its in the red zone, these all aluminum engines will warp very quick

Id suspect air in the coolant system though, did you try and put the heat to the highest 85 degree setting at all?? Thats where mine turns into an inferno blaster and almost burns you lol

[Chuck Tribolet]

Your big problem is that it goes to H. It shouldn't get past about the middle, esp. in those outside temps. Heck, the Dodge Caliber
rental we had for wedding in Wisconsin this weekend never got about about 1/4 of the way up.


Chuck

[Densetsu]

When's the coolant last been drained and filled or flushed and filled?

If it's recently, then it's probably air in the system.

If it's been more than 5 years, then your radiator could be clogged up with rust.

[howie]

This forum is the best. It works perfectly now.

To answer the questions: I hadn't tried turning the heat up to 85 because it was starting at 0 degrees F. And I have no idea when the coolant was flushed last (have owned for about 3 years) but the mechanic said there was a lot of air in the system.

Next need to post on the engine light that just came on. Knock sensor and one other code.

Thanks again!!