Lukewarm heat from vent?

Tiny
BHAMDOC1
  • MEMBER
  • 2013 BMW 335
  • 6 CYL
  • TURBO
  • 2WD
  • AUTOMATIC
  • 118,000 MILES
Takes forever to get some lukewarm to come out. Blower works fine; these are the codes I found. When I deleted them, I got one back which is in the picture that only shows one code (AUC). Can this affect heat? Coolant is full. I thought about the heater control valve, but I have not seen it on the driver side under the hood like most BMWs. Can you ee if there is one and where it is? Hoses to the firewall I would say are warm. I also suspect the thermostat but no codes or indications.
Images (Click to make bigger)
Thumb
Thumb
Thumb
Thumb
Thumb
Tuesday, January 14th, 2025 AT 10:09 AM

17 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
Does the engine get hot? If not, I would check the thermostat, but I can tell you the auxiliary water pump for the heater goes out all the time for these cars. You can remove it and put 12 volts to it and if it doesn't work, I would replace it, also check the fuse for it as well. Check out the images (below). Please let us know what happens.
Images (Click to make bigger)
Thumb
Thumb
Thumb
Was this
answer
helpful?
Yes
No
Wednesday, January 15th, 2025 AT 11:27 AM
Tiny
BHAMDOC1
  • MEMBER
  • 98 POSTS
This says bye E92, his is the F30, the newer style. And the pictures talk about the fuel lines or filter. Where is the auxiliary pump located?
Was this
answer
helpful?
Yes
No
Wednesday, January 15th, 2025 AT 11:30 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
Okay, my bad, here is the auxiliary water pump which can be either one, follow the heater hoses and you should be able to find it, they don't show the location. I updated the images above.
Was this
answer
helpful?
Yes
No
Thursday, January 16th, 2025 AT 8:57 AM
Tiny
BHAMDOC1
  • MEMBER
  • 98 POSTS
Can you let me know if the F30 335i has an auxiliary pump and where it is? The above is for the E92
Image (Click to make bigger)
Thumb
Was this
answer
helpful?
Yes
No
Thursday, January 16th, 2025 AT 8:57 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
I updated the images above. Did you see them?
Was this
answer
helpful?
Yes
No
Friday, January 17th, 2025 AT 11:14 AM
Tiny
BHAMDOC1
  • MEMBER
  • 98 POSTS
Yes, I am able to find new and used ones online but still don't know where it is. I'll check more.
Was this
answer
helpful?
Yes
No
Friday, January 17th, 2025 AT 11:59 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
Yep, I rechecked and it doesn't say where is is but it should be in the engine compartment. I would follow the heater hoses, should be connected to one of them.
Was this
answer
helpful?
Yes
No
Saturday, January 18th, 2025 AT 10:17 AM
Tiny
BHAMDOC1
  • MEMBER
  • 98 POSTS
One of the images you updated above is for a 4-cylinder, this is a 6-cylinder turbo. Heater hoses, one goes to a thermostat the other to the radiator.
Was this
answer
helpful?
Yes
No
Saturday, January 18th, 2025 AT 12:18 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
Maybe some one removed it? It says it is at the rear of the engine compartment. Check out the images (below). Please let us know what happens.
Image (Click to make bigger)
Thumb
Was this
answer
helpful?
Yes
No
Sunday, January 19th, 2025 AT 9:58 AM
Tiny
BHAMDOC1
  • MEMBER
  • 98 POSTS
That's the coolant pump. I verified with someone that only the M package has the aux pump behind the headlight. So am now just looking for where this heater control valve is. Strange hoses to connect to upper radiator and one to thermostat.
Was this
answer
helpful?
Yes
No
Sunday, January 19th, 2025 AT 10:09 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
My information says it does not have a heater control valve?
Was this
answer
helpful?
Yes
No
Monday, January 20th, 2025 AT 9:52 AM
Tiny
BHAMDOC1
  • MEMBER
  • 98 POSTS
Weird, so what controls it? I just did a pressure test, and a common art has busted leaking, it's the use from thermostat to cylinder head, always break, and I was smelling something before, so maybe it was not holding pressure, I will replace it and see.
Was this
answer
helpful?
Yes
No
Monday, January 20th, 2025 AT 9:56 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
Yep, you could also have an air bubble inside the heater core. Please go over this video, it might help:

https://www.youtube.com/watch?v=SNRb6pSwYuU

Once you get it back together, start the engine and allow it to get warm, then feel both heater hoses. Let me know what happens.
Was this
answer
helpful?
Yes
No
Tuesday, January 21st, 2025 AT 10:26 AM
Tiny
BHAMDOC1
  • MEMBER
  • 98 POSTS
Yes, I saw this video bee, and I let the system bleed itself electronically 3 times, but I think the small leak that I didn't see may have contributed so once I put it back I will re-bleed it first. As far as I can remember the hoses were warm but not hot.
Was this
answer
helpful?
Yes
No
Tuesday, January 21st, 2025 AT 10:28 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
They should be hot. Maybe the core is clogged, you might want to try to flush the core using a garden hose.
Was this
answer
helpful?
Yes
No
Wednesday, January 22nd, 2025 AT 8:37 AM
Tiny
BHAMDOC1
  • MEMBER
  • 98 POSTS
But if both are warm doesn't that mean the water is getting in and out of the core?
Was this
answer
helpful?
Yes
No
Wednesday, January 22nd, 2025 AT 9:19 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
Yes but if it is so little, it is not allowing the flow at all. I would check it if there were no heater control valve or aux water pump.
Was this
answer
helpful?
Yes
No
Thursday, January 23rd, 2025 AT 9:26 AM

Please login or register to post a reply.