No Heat
 

If not for the heated seats, I'd be freezing my butt off here in the great white north.

'07 X5 4.8i N62. No heat coming from either passenger or driver side vents, only cool air. Here's what I've checked / done so far:

• called up faults in ISTA. Unfortunately it seems ISTA cannot communicate with about 1/3 of the modules including JBE and IHKA, so I can't see any fault codes from there
• blower fan is working properly at all speeds, and selecting custom settings directs the air to footwell / face / windshield as expected.
• coolant level is fine, coolant reaches operating temperature of ~100C.
• cabin controls at full hot
• engine fan comes on intermittently as expected
• I reflexively replaced the heater control valve, but that didn't work. Both the new and old valves bench test fine: valves normally open at 0V, and closed at 12V. I disassembled the old valve and the seals were OK so nothing went downstream to clog the heater core.
• I purged the cooling system of air when I changed the heater control valve, so I don't suspect an airlock in the heater core.

Warm coolant just isn't making it to the heater core.

Here's what I'm going to try next:

• although I no longer suspect it has anything to do with the heater control valve, I'll complete my checks: verify that the ground is OK, and that there's 0V at the connector when calling for heat, and there's 12V and a solenoid click when not calling for heat.
• check the auxiliary water pump (how?)
• verify that the heater core isn't plugged (how?)
• see if I can resolve the ISTA module communication issue, but I don't know where to start

Anything else I should check?

Hmm, the internals of my old heater control valve don't look like this one: https://www.bimmerfest.com/threads/d.../post-11207073

That one has a torn seal around the valve which is missing from mine entirely. Now I'm wondering if my seals were torn up and went downstream to block the heater core.

Had similar issue last year with no heat on 09 E70, replacing the valve did the trick, sorry that didn't work. But saw your ISTA comment with no comm to modules, ran in circles until I found what it was, be sure latency is set to 1. Open “Device Manager”, then USB Serial Port properties, go to “Port Settings” tab and click
“Advanced...”. Change latency timer to “1”

Thanks - I'll check it out, but it's only some of the modules that ISTA cannot communicate with.


For my no heat problem, I'm beginning to suspect the auxiliary water pump. I'll get some heat after a 1/2 hour drive as if only a minor amount of coolant is making it to the heater core. Also, I cannot hear the pump when I activate heating in "rest mode". Before I dig through the wheel arch to get to it, does anyone know precisely when it's supposed to be on? I'm expecting +12V when calling for heat and in rest mode.

Don't recall an aux pump in my 09. Been a while since using ISTA but should be able to test the pump when going through troubleshooting. If seals did go downstream and causing blockage could removing hoses 5 and 6 then back flushing through 7 blow them out?
https://www.realoem.com/bmw/enUS/sho...diagId=64_1591

Aux pump is #1 in that diagram. ISTA may not be able to help me with that troubleshooting, as the IHKA module is one of the modules that it cannot communicate with.


I'm thinking that if the aux pump isn't pumping then it would impede any natural flow to the heater core. Therefore I think that pump has to be on for any coolant to flow to the heater core.



I'm going to check that pump first before back flushing the heater core. It looks like a bit of effort to get to the outlet.

Same comm error until I checked ISTA settings and latency issue.

I would think '07 and '08 would be fairly similar, but I didn't have to dig through the wheel arch to get to the aux pump. I had ok access in the engine compartment. I can't tell you when specifically it turns on, but if you hold accel pedal down with ignition on (engine off), it'll kick on. Supposed to help you bleed coolant. I could hear it run, but a hand on it will certainly be obvious if it's on or off.

I think I have a similar if not exactly the same problem. 2009 N62 V8 here. But my biggest suspicion is the electric flaps that regulate the air flow. Because my vents barely blow any air even when the fan is set to max, but after driving for some 15 minutes the car does warm up. So it can't be the valve, can it?