Strange heater behavior

gumanov · 03-03-2013, 11:36 PM

Hi all,
I'm having a weird issue with my 2004 330Ci cabin heat.
Recently replaced the thermostat since it was stuck open, and engine would never reach normal operating temp. New thermostat fixed that, but I'm still having a problem with low cabin heat.

At idle, using the AUTO mode, I'm not getting any heat at all, its all cool air, with engine at normal operating temp.
If i set the blower motor to manual low setting, i do get hot air out of the vents.. but no heat on max setting.

I'm using the BMW DIS diagnostic software to read the heater core temp sensor values.

Blower fan on manual MAX (full) setting - 20C
Blower fan on manual LOW (2 bars) setting - 70C

Any ideas as to why the heater core temperature falls so low when the blower fan is at MAX?
Thanks

gumanov · 03-04-2013, 12:49 PM

bump; Anyone?

taibinhvuong · 03-04-2013, 06:14 PM

Set the heat setting to max and report back the heat status.

gumanov · 03-04-2013, 08:59 PM

Heat settings at max (91F and blower motor at max speed) no hot air from vents. Air is cool...
Engine is at normal running temp, centered on gauge.

If set the blower motor to lowest speed, while still having temp set for 91F...I get hot air from the vents.

taibinhvuong · 03-04-2013, 09:48 PM

Put your hand on two hoses which connected to the Heater Control Valve locates below the airbox, both should be equally hot when set at max heat setting and at operating temperature, report back.

TurnersInOz · 03-04-2013, 10:12 PM

In short, you most likely need to bleed the system.

03-03-2013, 11:36 PM	#1
gumanov Registered User Join Date: Aug 2011 Location: USA Posts: 22 My Ride: 2001 325Ci 5-speed View My Garage	Strange heater behavior Hi all, I'm having a weird issue with my 2004 330Ci cabin heat. Recently replaced the thermostat since it was stuck open, and engine would never reach normal operating temp. New thermostat fixed that, but I'm still having a problem with low cabin heat. At idle, using the AUTO mode, I'm not getting any heat at all, its all cool air, with engine at normal operating temp. If i set the blower motor to manual low setting, i do get hot air out of the vents.. but no heat on max setting. I'm using the BMW DIS diagnostic software to read the heater core temp sensor values. Blower fan on manual MAX (full) setting - 20C Blower fan on manual LOW (2 bars) setting - 70C Any ideas as to why the heater core temperature falls so low when the blower fan is at MAX? Thanks __________________ 2001 325Ci 5spd 2004 330Ci ZHP 6spd :) Last edited by gumanov; 03-04-2013 at 12:04 AM.

03-04-2013, 12:49 PM	#2
gumanov Registered User Join Date: Aug 2011 Location: USA Posts: 22 My Ride: 2001 325Ci 5-speed View My Garage	bump; Anyone? __________________ 2001 325Ci 5spd 2004 330Ci ZHP 6spd :)

03-04-2013, 08:59 PM	#4
gumanov Registered User Join Date: Aug 2011 Location: USA Posts: 22 My Ride: 2001 325Ci 5-speed View My Garage	Heat settings at max (91F and blower motor at max speed) no hot air from vents. Air is cool... Engine is at normal running temp, centered on gauge. If set the blower motor to lowest speed, while still having temp set for 91F...I get hot air from the vents. __________________ 2001 325Ci 5spd 2004 330Ci ZHP 6spd :) Last edited by gumanov; 03-04-2013 at 09:00 PM.

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03-04-2013, 06:14 PM	#3
taibinhvuong Registered User Join Date: Mar 2006 Location: San Francisco Posts: 707 My Ride: E46 99' 328i View My Garage	Set the heat setting to max and report back the heat status.

03-04-2013, 09:48 PM	#5
taibinhvuong Registered User Join Date: Mar 2006 Location: San Francisco Posts: 707 My Ride: E46 99' 328i View My Garage	Put your hand on two hoses which connected to the Heater Control Valve locates below the airbox, both should be equally hot when set at max heat setting and at operating temperature, report back.

03-04-2013, 10:12 PM	#6
TurnersInOz Registered User Join Date: Dec 2011 Location: Brisbane Posts: 340 My Ride: 2004 325i View My Garage	In short, you most likely need to bleed the system.