No heat

Hey all. I'm a new BMW owner, bought a used 2005 545i a few months ago. Has mostly been running great and I've really been enjoying the ride But recently I ran into an issue: no heat.

The other day it got cold for the first time since I bought it so I turned the temp dials up, anticipating some heat... but nothing. Even with the temp dials all the way to the right, when I hit "Auto" the AC light comes on and the fan goes to max, blasting cold air. If I manually turn off the AC and take it off "Auto", still no heat. I checked "Vent Settings" in idrive and made sure it was on the "Red" mode. I also tried Defrost, but no luck. I took it to my independent guy but he couldn't find anything wrong with it; said everything checked out.

One thing to note: About a month ago the low coolant warning came on, so I refilled it. About a week later, low coolant again. I take it to my indy guy, he said I had a cracked bypass tube and replaced it. Haven't seen the low coolant warning since, but I have been checking the coolant regularly and I have noticed a very small reduction in the coolant level. I figure there might be a small leak somewhere else, but for now I'll just monitor the coolant level since it might be my imagination; or if not it's a very slow leak (if anything). Checked recently and there's still plenty of coolant in the system. When I took it back in for the no heat problem, I asked about the coolant level, but he said he couldn't find any leak.

I just took it into the dealer so we'll see what they say, but I have a couple questions hopefully somebody can answer in the meantime.

1. What's the expected behavior when the temp dials are set to max and you hit "Auto"? Seems to me the A/C shouldn't come on, but maybe I'm crazy... Could this indicate a malfunctioning temp sensor?
2. Could a very small leak somewhere in the coolant system cause no heat? I'm thinking maybe if there's another leaky pipe or a small crack in my radiator, there isn't enough pressure for the heater? But like I said the leak, if any, is very small.
3. A lot of posts say to bleed the air from the cooling system, and after replacing the bypass tube I didn't do this so I'll give it a try if the dealer can't find anything else.

Any thoughts/ideas would be very appreciated. Thanks!

It's perfectly normal for the AC to come on when you press auto. Not only does the AC cool the car, it also removes moisture from the air. For the no heat, I would look into whether your water valve is working or not. It failed on my old 330 but the symptoms were opposite, all I got was heat. I'm assuming your thermostat is ok or you would get a check engine light.

Check your vent settings in idrive. If they're set to blow cold on you, they'll blow cold. This is a frustrating thing for me, having to adjust this as the season changes. Do you have an owners manual? If not, get one, or you can download one from BMW's site.

Originally Posted by Locomotivebart

It's perfectly normal for the AC to come on when you press auto. Not only does the AC cool the car, it also removes moisture from the air. For the no heat, I would look into whether your water valve is working or not. It failed on my old 330 but the symptoms were opposite, all I got was heat. I'm assuming your thermostat is ok or you would get a check engine light.

Turns out there were two problems: the valve unit was broken, and my auxiliary heat pump was dead. Thanks for the help!

I had a similar problem a couple weeks ago. In my case the dealer had to replace the thermostat.

Dealer says mine is fine. takes forever to heat up. I saw a "red fan light" yesterday for the first time light up, didnt even know it was there. Now I can not get that duplicated. I am so frustrated. Checked in the iDrive and all the settings are correct. Its driving me nuts.

I also have a similar problem. I like heat from the floor, but I only get heat above and my feet freeze.
The passenger side seems ok. It might be a bad heat door????
Yes I adjusted the i drive.

Why is this car so needlessly complex. AND the complexity makes the system worthless.

At least if all this worked well we would all applaud, but it doesnt.

Going through similar issue right now - not a fun scenario. Was driving on the freeway last night and no warm air was coming from the vents, even with idrive settings and control knobs set to high. A few minutes later, a yellow thermometer signal appeared on the dash and a message in idrive indicated to drive moderately. As I was changing lanes to hopefully exit the freeway, the thermometer indication went to red and idrive displayed a message to pull over and turn the engine off - then the car went into limp mode. I made it to the emergency lane and killed the engine, but it is not fun being stuck there while cars are going by at 70 mph. While I was on the phone with BMW Assist, CHP stopped by and advised me to exit the freeway. I was able to start the car at that point and proceed in limp mode to the freeway exit while the CHP escorted me along the way to keep me safe. Then I got to wait another 1-1/2 hours between dealing with BMW Assist and waiting for the flatbed to arrive.

I guess, some folks experiencing thermostat stuck close or water-pump failures. Please keep us in the loop cause this could be the new achilles heel on N54 engine.

Originally Posted by lbcdude

Going through similar issue right now - not a fun scenario. Was driving on the freeway last night and no warm air was coming from the vents, even with idrive settings and control knobs set to high. A few minutes later, a yellow thermometer signal appeared on the dash and a message in idrive indicated to drive moderately. As I was changing lanes to hopefully exit the freeway, the thermometer indication went to red and idrive displayed a message to pull over and turn the engine off - then the car went into limp mode. I made it to the emergency lane and killed the engine, but it is not fun being stuck there while cars are going by at 70 mph. While I was on the phone with BMW Assist, CHP stopped by and advised me to exit the freeway. I was able to start the car at that point and proceed in limp mode to the freeway exit while the CHP escorted me along the way to keep me safe. Then I got to wait another 1-1/2 hours between dealing with BMW Assist and waiting for the flatbed to arrive.

Turns out it was a problem with the water pump. The SA said that they are starting to see a number of 535's coming in with water pump issues.

Originally Posted by lbcdude

Turns out it was a problem with the water pump. The SA said that they are starting to see a number of 535's coming in with water pump issues.

Just had the same problem a couple of weeks ago in my 06' with 67400 on the ODO

Originally Posted by Sloan165

Just had the same problem a couple of weeks ago in my 06' with 67400 on the ODO

Looks like the lifespan of electric WP is about the same as belt-driven one, about 5-6 years and 60Kmiles. The N52 and N54 don't use the same part number on WP, BTW.

I am keeping an eye on mine closely, my 535i produces good heat through the vent but not super hot like it used to, and after engine shut-off the WP kicks-in longer than usual. No code nothing just observation, and mine is 4.5yr old with 32kmiles.

Did any of you who had failed WP loosing coolant prior? just wondere if the bearing leaks like the belt-driven before it decides to go South.

Originally Posted by HPIA4v2

Looks like the lifespan of electric WP is about the same as belt-driven one, about 5-6 years and 60Kmiles. The N52 and N54 don't use the same part number on WP, BTW.

I am keeping an eye on mine closely, my 535i produces good heat through the vent but not super hot like it used to, and after engine shut-off the WP kicks-in longer than usual. No code nothing just observation, and mine is 4.5yr old with 32kmiles.

Did any of you who had failed WP loosing coolant prior? just wondere if the bearing leaks like the belt-driven before it decides to go South.

Yes! Mine was slowly leaking (about 20oz. per month) for 2 months, however my radiator was leaking at that point.