[Mcnelly]

E90 328i.. with winter around the corner I'd like to fix this issue before I need it..

So last winter I noticed the passenger side and rear vent will blow warm air before the driver side. It'll take 30 minutes sometimes before the driver vents start to blow warm air.

The whole time the windshield likes to fog up and makes it a pain to see.

I've read that the heater core is a two piece setup for the duel hvac and that the drivers side "could" be partially plugged? But I've also seen something talking about a heater valve as well that could cause this?

Anyone able to shed some light on this situation?

[gbalthrop]

Originally Posted by Mcnelly

E90 328i..[2008] ... passenger side and rear vent will blow warm air before the driver side. It'll take 30 minutes sometimes before the driver vents start to blow warm air. The whole time the windshield likes to fog up and makes it a pain to see. [THAT suggests your Evaporator (A/C) is NOT "de-humidifying".]... I've also seen something talking about a heater valve as well that could cause this?...

Is your A/C cooling the car NOW as it should?
When you press MAX button in center of Left T-stat, does cool/cold air come from ALL Vents?
When you press Defrost button on Right of Climate Control Panel, does warm air come from Windscreen Vents and Blower @ High Speed?
Do you have INPA/ISTA, or any Scan Tool that can connect to IHKA Module & read Live Data?

If you were turning Compressor Valve OFF ("Snowflake" button) last winter to get warmer air, that would explain "fogging", as you need the Evaporator (cooling) coil to be cold to "De-humidify".

You have only ONE Heater Core and the tubes are on the LEFT or US Driver-side of the unit. So a clogged heater core would NOT cause the symptoms you describe. Also, US vehicles normally do NOT have a Heater Control Valve to shut off coolant flow through the heater core, AND even if yours has such a valve, it would affect BOTH sides.

Your vehicle DOES have TWO Thermostats, which control TWO "Mixed-Air Flaps". Those flaps, IF operating correctly, send NO, Some, ALL of the air which has passed through the Evaporator/ Cooling coil, through the heater core to regulate temperature of air delivered to the vents.

INPA or ISTA would show exact position of each of the two flaps. You can test function of those Mixed-Air Flaps, to SOME degree without diagnostic software, as follows (Test with Warm Engine):
A) Put BOTH T-stats on 60 (Coldest) & wait 30 seconds;
B) Put Right T-stat on 84 (Warmest) and listen for flap motor whir or flap "clunk"; Feel temp of air delivered and see if it changes on Right Vents;
C) Change Left T-stat to 84 (Warmest), listen for/ compare flap motor sounds, and Left Vent air delivery temp.

My guess is that your LEFT Mixed Air Flap Motor is NOT functioning as it should, and perhaps is NOT moving at all, stuck in near "full cold" position. INPA or ISTA would show the exact position of that Flap in less time than it took you to read this.
George

[Mcnelly]

Originally Posted by gbalthrop

Is your A/C cooling the car NOW as it should?
When you press MAX button in center of Left T-stat, does cool/cold air come from ALL Vents?
When you press Defrost button on Right of Climate Control Panel, does warm air come from Windscreen Vents and Blower @ High Speed?
Do you have INPA/ISTA, or any Scan Tool that can connect to IHKA Module & read Live Data?

If you were turning Compressor Valve OFF ("Snowflake" button) last winter to get warmer air, that would explain "fogging", as you need the Evaporator (cooling) coil to be cold to "De-humidify".

You have only ONE Heater Core and the tubes are on the LEFT or US Driver-side of the unit. So a clogged heater core would NOT cause the symptoms you describe. Also, US vehicles normally do NOT have a Heater Control Valve to shut off coolant flow through the heater core, AND even if yours has such a valve, it would affect BOTH sides.

Your vehicle DOES have TWO Thermostats, which control TWO "Mixed-Air Flaps". Those flaps, IF operating correctly, send NO, Some, ALL of the air which has passed through the Evaporator/ Cooling coil, through the heater core to regulate temperature of air delivered to the vents.

INPA or ISTA would show exact position of each of the two flaps. You can test function of those Mixed-Air Flaps, to SOME degree without diagnostic software, as follows (Test with Warm Engine):
A) Put BOTH T-stats on 60 (Coldest) & wait 30 seconds;
B) Put Right T-stat on 84 (Warmest) and listen for flap motor whir or flap "clunk"; Feel temp of air delivered and see if it changes on Right Vents;
C) Change Left T-stat to 84 (Warmest), listen for/ compare flap motor sounds, and Left Vent air delivery temp.

My guess is that your LEFT Mixed Air Flap Motor is NOT functioning as it should, and perhaps is NOT moving at all, stuck in near "full cold" position. INPA or ISTA would show the exact position of that Flap in less time than it took you to read this.
George

Thanks for the respond!
With the "MAX" on air comes from all the vents perfectly the cooling fan gets crazy loud though.

When I switch temperatures for the driver's side the air flow comes damn near to a stop and you can barely feel it but can hear something moving. Maybe not fully opening to where it needs to be?

The only scan tool I currently have is the Carly brand but I may need to switch to a different type of scanner