Heater going bongos

[alexandre]

The temperature this morning was -5F (after a -20F night), and my HVAC heating decided that it would take a vacation today.

It was blowing cold air at all temp settings (I tried 62F to 90F), and fan speeds were all over the place at AUTO. The various fan speeds worked if selected manually, but still blowing cold. The selector between the dash fans is set to the 3 red dots. Coolant heat was right at 12 o'clock 2 mi into my 12 mi commute.

FSR and heater valve ? The thermostat is 2 years old and has about 40k on it.

[kayger12]

Agree with your thoughts. Fan sounds like the FSR. Lack of heat sounds like the heater valve if coolant level is good and hoses are firm.

[alexandre]

Alright. Do you have to flush coolant to replace heater valve ?

[kayger12]

No need to flush, but you'll want to bleed the system when you're done.

DIY here http://forum.e46fanatics.com/showthread.php?t=617301

[alexandre]

I just thought about something. I've procrastinated on some air presence in my cooling system. I know because the coolant light turns on every 4-5 minutes, lasts for 2-3 minutes, and turns off from time to time... Level is fine. I'm thinking maybe that air pocket ended up in the heater core and that's why it was blowing cold.

Does coolant circulate faster at higher RPM ? I was driving like a grandpa this morning, shifting at 2k rpm and accelerating gradually since the engine was so cold. I usually shift at 3-4k rpm, and go up to 6 when entering the highway (just because this engine at high revs is music). If coolant barely moved during my commute that could explain my air in the heater core theory.

I'm way overdue for a flush anyway, so I'll probably do it when it gets a little warmer here before throwing parts at the car.

[kayger12]

I would check your level with the car running, heat on high, fan on low.

Your level might look good when the car is off but drop when you're pulling coolant into the heater core when it's running and the heat is on.

Air pocket in the core would certainly explain the symptoms so if you've had a bleed issue I'd start there. Not to mention it's the quickest and cheapest fix.

[alexandre]

Definitely coolant. I've been paying attention to the temperature of the air coming out and it alternates cold <> hot on a regular interval... Air pocket circulating in the system. I'll flush it ASAP.

OTOH I also noticed that my driver's heated seat was behaving erratically. When I put it on the lowest setting it just shuts off 30 sec after. On max it heats up properly. I read a bit about it and it could be a chewed up wire, dead switch or something else. I'll look into it.

Dunno why all my heating devices stop working when it's -15F. http://www.weather.com/weather/right-now/Montreal+Canada+CAXX0301 I still love this car :biggrin