[Cixpak88]

Hi All,

Im having a no-heat problem and am hoping someone can help sort it out.

If you turn on the heat, the blower stops blowing air.

If you turn on AC, it blows plenty of air.

If you flip between Max AC and Defrost/heat, by constantly pushing the buttons, the air blows hot before cooling off. I hope this makes sense.

Bottom line is the heat is there, but the blower won't push it, even though the blower works.

The center vent controls are on heat (red). Auto and manual both don't work unless it's for cool air.

I ordered a heater control valve, but seeing as how the heat is there, I feel this probably isn't the problem.

At the point I'm thinking it's a problem with the HVAC controller. Thoughts?

Very frustrating. Any input is greatly appreciated.

[95blkmax]

If you or someone you know have access to ISTA, that has test plans for both the heater valve and the IHKA (HVAC control panel).

It also has a test plan for blend door actuators on the HVAC box. If the flap actuator for the hot air ducts is faulty, you'll get all the cool air you want, and no hot air once the cool air flaps close and the hot air ducts wont open.

If no ISTA, there are OBD software that can read BMW-specific codes like BimmerCode or Carly

[Cixpak88]

Originally Posted by 95blkmax

If you or someone you know have access to ISTA, that has test plans for both the heater valve and the IHKA (HVAC control panel).

It also has a test plan for blend door actuators on the HVAC box. If the flap actuator for the hot air ducts is faulty, you'll get all the cool air you want, and no hot air once the cool air flaps close and the hot air ducts wont open.

If no ISTA, there are OBD software that can read BMW-specific codes like BimmerCode or Carly

Thanks for the info. I do have the Foxwell scan tool. Do you know if it has the capabilities you mentioned?

[Cixpak88]

Originally Posted by Cixpak88

Thanks for the info. I do have the Foxwell scan tool. Do you know if it has the capabilities you mentioned?

I answered my own question - thanks. The tool can calibrate the valve.

[Blue Angel]

Just a shot in the dark here. Many cars have a temperature sensor that won't allow the fan to blow until the coolant is above a certain temperature. Keeps from blowing cold air on occupants.

If this sensor is separate from the main engine temp sensor, and if it went bad, it could be making the car think the coolant is not up to temp and telling the fan not to run, but it would run if there was no demand for heat.

There's also an interior ambient temp sensor that, if failed, could lead the car to think it's already warm if it's not. Worth checking maybe?

No idea if that's how this system works or not.

Can you get heat if you put in manual mode and set the fan speed?

[Cixpak88]

Originally Posted by Blue Angel

Just a shot in the dark here. Many cars have a temperature sensor that won't allow the fan to blow until the coolant is above a certain temperature. Keeps from blowing cold air on occupants.

If this sensor is separate from the main engine temp sensor, and if it went bad, it could be making the car think the coolant is not up to temp and telling the fan not to run, but it would run if there was no demand for heat.

There's also an interior ambient temp sensor that, if failed, could lead the car to think it's already warm if it's not. Worth checking maybe?

No idea if that's how this system works or not.

Can you get heat if you put in manual mode and set the fan speed?

Thanks for the reply.

Can't get heat in manual mode either. Can get cool air, so you may be on to something with the engine temp sensor.

To be clear, if I set it to hot, I hear the fan but get no air circulation.

If I set it to cool, I get air circulation.

It's almost as if the blend doors are stuck closed?

I tried to recharged the AC yesterday in the off chance that could be the issue. It was already full.

I believe there's a blend door actuator that could also be a problem. I'm at a loss.

[Blue Angel]

Originally Posted by Cixpak88

To be clear, if I set it to hot, I hear the fan but get no air circulation.

If I set it to cool, I get air circulation.

It's almost as if the blend doors are stuck closed?

Ah, if the fan spins up but you get no airflow, then I think you're onto something with the blend doors etc. Doesn't make sense why the fan is on and no airflow.

Maybe the stepper motor has lost its zero and is closing an air path instead of opening? I had an issue like that with my Chevy Cruze and the recirc doors; they were not clocked properly. I had to manually set them, after which they worked fine. I'll paste a video link. It may or may not help, but might be worth checking if possible.

[Blue Angel]

Again, just in case there could be a similar situation with an actuator motor that's lost it's zero position.

[ezaircon4jc]

Does BMW use blend doors? My last car didn't, it used a heater control valve.

[Cixpak88]

Thank you, all, again for the input.

After reading countless threads about heater control valve issues, I went ahead and replaced it.

Now no heat or AC. The blower won't even kick on.

Tried bleeding the system using the accelerator pedal in "on" position method and it won't run through the bleeding cycle.

Any thoughts?

[Blue Angel]

I don't have any more to offer. Sucks that the issue is getting worse, not better.

I would be interested in seeing pics of the heater valve replacement if you have them. What is the part number?

[Cixpak88]

Originally Posted by Blue Angel

I don't have any more to offer. Sucks that the issue is getting worse, not better.

I would be interested in seeing pics of the heater valve replacement if you have them. What is the part number?

The issue with no blower motor functionality was the plug for the control valve wiring. It's kind of a mess from past repairs, I imagine.

I was able to fix this and now the blower motor kicks on, but there's still no air movement, like before. I was able to get the system to bleed as well

The brand and part number I used was Gates EHV110.

I found several codes related to the HVAC system this AM…. 23 to be exact. Most of these point to a bad HVAC panel (not sure the technical name).

Will update as I make progress.

Thanks again.

[JTURN3R]

Originally Posted by 95blkmax

If you or someone you know have access to ISTA, that has test plans for both the heater valve and the IHKA (HVAC control panel).

It also has a test plan for blend door actuators on the HVAC box. If the flap actuator for the hot air ducts is faulty, you'll get all the cool air you want, and no hot air once the cool air flaps close and the hot air ducts wont open.

If no ISTA, there are OBD software that can read BMW-specific codes like BimmerCode or Carly

Thankyou for your help!

[Cixpak88]

After all of this, it turns out there's a bad connection either at the HVAC control panel or further down the harness. Wiggling wires and the plug seems to fix the issues.

Just wanted to let you all know in case you are chasing the same problem.

[95blkmax]

Originally Posted by Cixpak88

After all of this, it turns out there's a bad connection either at the HVAC control panel or further down the harness. Wiggling wires and the plug seems to fix the issues.

Just wanted to let you all know in case you are chasing the same problem.

interesting! certainly begs the question if anyone had been poking around in there prior to you discovering this

[Blue Angel]

I've seen people have random issues after removing the hvac controls and reinstalling them without getting the connectors properly seated. Perhaps that's the issue?

[Johnkwick]

Originally Posted by Blue Angel

I've seen people have random issues after removing the hvac controls and reinstalling them without getting the connectors properly seated. Perhaps that's the issue?

I've been dealing with no heat issue for months

Just did all heating related tests in ISTA and apparently no fault code thrown during the tests. It's like the aircon is stuck at 16C. Whenever I dial the knob to 17C, dual heating valve will immediately open(that's what ISTA shown to me but to be honest I'm not sure if ISTA only read by voltage to determine the open/close status without considering the actual mechanical position). Heat exchanger stuck at 3-5C regardless the stratification dial and temp dial position.

I'm a bit loss here what should I fix. Maybe I'll start with opening the hvac control and wiggle the cable

[Blue Angel]

It doesn't take long to do and would help determine if a flaky connection was the culprit. Pull the hvac control panel and undo/re-seat the connectors and see if it helps. Could be a half hour well spent.