SOLVED 2006 4.4i Heat Only During First 15 Minutes and at Idle

[TC2]

Hello everyone,

I am currently trying to resolve an intermittent heat issue with my 2006 4.4i. I hadn't driven it in about a year so I figured I would put some miles on it recently.

The heat had stopped working around that time and I discovered recently that I had knocked off the connector for the center mixing vent dial which I reconnected.

When I first start driving and the engine warms up I have full heat in the cabin out of the front and rear seat vents. Almost hot enough to burn my hands.

I have been doing mostly highway driving so after about ten minutes on the highway I can feel the air starting to cool off until it is blowing cold.

When I come to a stop it starts blowing heat again.

There are no warning lights on right now. Yesterday I used DIS to check if the IHKA module had any stored codes and it did not. I also tested the auxiliary water pump with DIS and I can hear it running.

I've never changed the coolant so I don't believe there is air in the system. I topped it up yesterday. It might have been a cup or two low.

The only thing I noticed, which I can't find any definitive information on, is with the heat set to 90F and fan speed on low I don't see a stream of coolant coming through the expansion tank as I have read should be the case.

Does anyone have any ideas regarding this? I would appreciate any assistance.

[80stech]

Check to see if you the stream at the top of the expansion tank when you run the aux cooling pump. Open the bleed screw when you have a stream running and triple check that you don't have air in the system. How did the connector for the vent get knocked off? Have a quick look at the grille for the temp sensor fan on the IHKA.

[TC2]

I appreciate the response.

That's the thing. I have never seen a stream coming out at the top of the expansion tank. I started it and let it warm up and could see a very small amount of coolant coming out of the small hole at the top, but not a steady stream like I have seen in some videos.

I have the equipment to vacuum the system and fill it so I am considering draining the cooling system and trying that.

In regard to the bowden cable for the center vent. I had removed the glovebox and replaced the expansion valve for the A/C as I was trying to fix a non working A/C issue. It ultimately turned out to be the compressor which I replaced, but still have a leak. I recently purchased a new condenser and evaporator so I can completely service the A/C system and get it working again.

It crossed my mind that there might be an issue with the temp sensor in the IHKA, but it was reporting properly based on INPA and DIS. There is a small amount of dust, but nothing significant. What were you thinking regarding the temp sensor fan?

[TC2]

Also, if it's relevant, this X5 has a little over 65k miles. So it's not likely any of these components have been touched in the past.

[80stech]

There should be a nice stream of coolant at the top of the expansion tank with the aux pump running so that might be the first thing to check into. I'm only familiar with the 3.0L though so maybe someone can chime in if the V8s are different??

[TC2]

I'm also wondering if there is an issue with the heater control valve.

A couple years ago when I replaced the valve cover gaskets I accidentally broke one of the mounting ears off of the original one and replaced it with a new genuine BMW part. But I had some rodent issues and a squirrel chewed half of the wiring harness off on the driver's side of the engine bay and I rewired everything.

There might be a wiring issue with the heater control valve.

[guntherrex]

isn't it just the climate control turning the heat down once the car is up to temperature?

[TC2]

The temperature doesn't automatically adjust as far as I am aware.

I keep it set at 90F for testing and it never changes.

[80stech]

Both the aux coolant pump and heater control valve are easy to get to so you might want to check both. If I recall the heater valve is normally open so less likely there is a problem with the valve itself but you could try unplugging the heater valve to eliminate posible issues with it being closed ny the IHKA.

[TC2]

I unplugged the heater valve before my drive tonight and the heat worked constantly and never cooled off.

It was blowing full heat regardless of temp selected on the IHKA which makes sense considering it was unplugged.

What does this mean? Issue with the IHKA module? Possibly wiring issue where I rewired the heater valve?