Heater blowing cold

01-09-2024

Has anyone had this problem?

Heater blows "warm-ish".... and does get warmer if I run the RPMs high.... but at idle, blows cold. If sitting at idle for any length of time... blows very cold.

Coolant level is perfect
Engine warms up and maintains correct temperature consistently without issue or variation
No CELs or warning lights.
No changes to I-drive settings, etc. It's all been checked.
Fan/blower speed seems to be appropriate - Plenty of air moving, air is just cold at idle
Problem is consistent whether air is recirculated, or "fresh" air is chosen - Same problem.

Anyone had this issue?
Any ideas?

02-29-2024

No one replied after almost 8 weeks..... and there's a reason.

My car has been at the BMW dealership.... for 22 days (Yes, twenty-two)

They have torn the dashboard out twice (10 hour job each time)

They have replaced the heater core, hoses, electrical components, motorized vents, and likely a lot more I don't know (or care to know) about.

This one stumped a TEAM of BMW technicians for over 3 weeks.

(drum roll)

***** AUXILLARY WATER PUMP ******

Yea... I didn't even know such a thing exists in these cars. As it turns out, the water that goes through the heater core?? Is actually fed via an electric pump... NOT the (traditional) water pump.

But... it makes perfect sense..... if the engine was running at high RPMs, I had some "moderate" heat... but at idle... I had nothing but cold air.

Problem solved.... car is back in my hands... running as good as ever. I decided to not trade it in, and just keep it.... but it's currently back in "stock-looking" form.... going a different styling direction with it.

12-09-2024

I am going through this on my X5 and the dealer wants to rip my dash apart. My warranty company is declining to cover it saying the heater core is not covered unless leaking.

An independent shop says it's the check valve which is also not covered. I personally believe it's the motor as it no longer seems to be running on or at remote startup.

No-one wants to listen to me and its a 5hr job and not one I want to encounter as bleeding this system is not my idea of a cup of tea.

12-18-2024

So took the car to 3 shops. Dealer wanted to replace the heater core at $5000

Independent diagnosed a faulty control valve, $1,200

Dealer I bought the car from Diagnosed the thermostat. $ free

Do I let the selling dealer attempt to fix it first. Then I asked the independent to replace the HVAC water pump and control valve as they are next to one another. Also paid for Anti Dazzle coding while at the shop and this fixed it.

Thanks for the idea where to look. Without this I would have been out some 8k for sure.

02-12-2026

Same issue as you. Sometimes I get heat, but not all the time.

After 3 days of diagnosing, local dealer says heater core and about $4,500 to replace.

I have an extended warranty so I'm not too concerned about the price, just hoping it actually fixes it. I've seen posts about a control valve behind the headlight, as well as other items that could also be the culprit.

I fell like my X5 is a kid in boarding school. I never see it but I know it's somewhere safe, and whenever it's away it costs me money.

02-14-2026

Damn man your still here too.. how's the X5 running still after being tuned for so long?
I just replace my aux pump, rear main seal, intake manifold seal and all coolant lines. I have about 120k miles on it but never tuned it. Now I'm looking at adding the third row.

02-25-2026

Mjbmw1 wrote
Damn man your still here too.. how's the X5 running still after being tuned for so long?
I just replace my aux pump, rear main seal, intake manifold seal and all coolant lines. I have about 120k miles on it but never tuned it. Now I'm looking at adding the third row.

Yep... still here. However, I traded in the X5 a few days ago (less than a week) on a 2021 840i.

My 60-80 minute commute made no sense in a heavily modified, 700+hp SUV.

My front diff started leaking.... and i had some issues with the TPMs going haywire..... but no blown diffs, transmissions, transfer cases, etc.... and the engine runs like a champ.

Admittedly, i drive easy, and religiously replace the fluids (including the xfer cases).... may be that helped?

Yea... I miss the X5.... but it just didn't make any sense to keep it anymore.

Last page of my progress thread has pics of the new 840i

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Heater blowing cold