[whyyoumontague]

Howdy all,

Recently finished putting in a replacement motor (40k mi) after my 2015 335 (140k mi) spun a bearing. I could really use some help diagnosing a cabin heating issue. I'm feeezing in my car.

Now that temps have fallen I am realizing I have no heat, and even less as temps drop lower. At 40+ deg F it will blow warm out of the far driver side vent and some very Luke warm out of the left-center vent. Any lower temps (today it is 15 degrees, just blows cold. Both passenger vents blow ice cold all the time. Dual climate set to 84 and stratification wheel set to hot.

When parked, the temp of the air on drivers side will go up a bit but not much, and then will shoot back down while driving.

Oil temp reads ~200 and in the hidden menu it says my coolant temp is ~200 after 20 mins driving. Could I have not bled coolant correctly? Is my new thermostat bad? Heater core? Blend motor??

SOS

[njdangelo]

Originally Posted by whyyoumontague

Howdy all,

Recently finished putting in a replacement motor (40k mi) after my 2015 335 (140k mi) spun a bearing. I could really use some help diagnosing a cabin heating issue. I'm feeezing in my car.

Now that temps have fallen I am realizing I have no heat, and even less as temps drop lower. At 40+ deg F it will blow warm out of the far driver side vent and some very Luke warm out of the left-center vent. Any lower temps (today it is 15 degrees, just blows cold. Both passenger vents blow ice cold all the time. Dual climate set to 84 and stratification wheel set to hot.

When parked, the temp of the air on drivers side will go up a bit but not much, and then will shoot back down while driving.

Oil temp reads ~200 and in the hidden menu it says my coolant temp is ~200 after 20 mins driving. Could I have not bled coolant correctly? Is my new thermostat bad? Heater core? Blend motor??

SOS

That's possible. Another possibility is the thermostat is in upside down. No codes or anything? The symptoms you're describing lead me to believe the warm coolant isn't getting to the heater core. This would happen if the thermostat never registered a warm temp. I would double check the thermostat, then go through the bleeding procedure again.
EDIT: the thermostat is new and OEM right? You didn't reuse the one from the old engine?

[whyyoumontague]

Originally Posted by njdangelo

That's possible. Another possibility is the thermostat is in upside down. No codes or anything? The symptoms you're describing lead me to believe the warm coolant isn't getting to the heater core. This would happen if the thermostat never registered a warm temp. I would double check the thermostat, then go through the bleeding procedure again.
EDIT: the thermostat is new and OEM right? You didn't reuse the one from the old engine?

Originally Posted by njdangelo

That's possible. Another possibility is the thermostat is in upside down. No codes or anything? The symptoms you're describing lead me to believe the warm coolant isn't getting to the heater core. This would happen if the thermostat never registered a warm temp. I would double check the thermostat, then go through the bleeding procedure again.
EDIT: the thermostat is new and OEM right? You didn't reuse the one from the old engine?

it's possible to install upside down??? Yes new and OEM. The part that's weird to me is that it will blow hotter air when it's warmer. Wouldn't that mean warm coolant has to get to the heater core? I could prob squeeze the coolant line in to feel for warm?

Edit: I did squeeze what I believe are the coolant lines to the heater core (right next to the refrigerant lines) and they are definitely hot.

[Billfitz]

If the lines to the core are hot then the core should be hot, so that points to the heater vent flaps being at fault. Either they're stuck in the closed position or they're not getting the command to open.

[njdangelo]

Originally Posted by whyyoumontague

it's possible to install upside down??? Yes new and OEM. The part that's weird to me is that it will blow hotter air when it's warmer. Wouldn't that mean warm coolant has to get to the heater core? I could prob squeeze the coolant line in to feel for warm?

Edit: I did squeeze what I believe are the coolant lines to the heater core (right next to the refrigerant lines) and they are definitely hot.

Sorry just realized the thermostat is actually integrated into the housing on your car so chances are very unlikely that it could be installed upside down. also the hot coolant making it in and out of your heater core means its functioning properly. might be time to have ista hooked up to it to try some troubleshooting. i'd certainly go that route before throwing parts at it.

[whyyoumontague]

Originally Posted by njdangelo

Sorry just realized the thermostat is actually integrated into the housing on your car so chances are very unlikely that it could be installed upside down. also the hot coolant making it in and out of your heater core means its functioning properly. might be time to have ista hooked up to it to try some troubleshooting. i'd certainly go that route before throwing parts at it.

Originally Posted by njdangelo

Sorry just realized the thermostat is actually integrated into the housing on your car so chances are very unlikely that it could be installed upside down. also the hot coolant making it in and out of your heater core means its functioning properly. might be time to have ista hooked up to it to try some troubleshooting. i'd certainly go that route before throwing parts at it.

Thank you for your help, I'm going to do that as soon as I get a minute to. The other night when I had it hooked up here's the faults I got. I wonder if that AUC fault has to do with this? When I hit the recirculation button manually I hear the flaps change and blow noticeably different (but not temp)

[IMG][/IMG]

[kickthecan]

You can also try to flush and backflush the heater core. My car did the same, even when the hoses leading to the core and out were hot, the cabin wasn't getting any of the heat.

I did go the ISTA route to trigger all the flaps before flushing.

Be careful of the pressure of the water used while flushing though, you definitely don't want to cause a leak at the core since it's inside the dash

[im_an_alien]

Comes down to improper or incomplete bleeding

[whyyoumontague]

Originally Posted by im_an_alien

Comes down to improper or incomplete bleeding

Originally Posted by im_an_alien

Comes down to improper or incomplete bleeding

I know there's probably a couple good resources here on it but I have failed in finding what I could do differently. Any tips?

[kickthecan]

Originally Posted by whyyoumontague

I know there's probably a couple good resources here on it but I have failed in finding what I could do differently. Any tips?

Much easier than the good old E46

At least heat issues are easier than AC issues

[whyyoumontague]

Originally Posted by kickthecan

Much easier than the good old E46

At least heat issues are easier than AC issues

Originally Posted by kickthecan

Much easier than the good old E46

At least heat issues are easier than AC issues

Car warm/cold? Cap open/ closed? Bleeder screw?

[kickthecan]

Originally Posted by whyyoumontague

Car warm/cold? Cap open/ closed? Bleeder screw?

He literally shows you in the video but for those who can't watch:

Turn on acc mode
Heat max
Lowest fan setting
Hold down accelerator for ten seconds, you should hear the water pump activate
I left cap open, he mentions it's up to you, I'd rather not use the screw there

Just let it cycle and if you're not sure, do it again

You don't ever ever want to open the coolant tank when the car is hot since it's pressurized.

After that warm the car up and see if heat comes out

[whyyoumontague]

Originally Posted by kickthecan

He literally shows you in the video but for those who can't watch:

Turn on acc mode
Heat max
Lowest fan setting
Hold down accelerator for ten seconds, you should hear the water pump activate
I left cap open, he mentions it's up to you, I'd rather not use the screw there

Just let it cycle and if you're not sure, do it again

You don't ever ever want to open the coolant tank when the car is hot since it's pressurized.

After that warm the car up and see if heat comes out

Originally Posted by kickthecan

He literally shows you in the video but for those who can't watch:

Turn on acc mode
Heat max
Lowest fan setting
Hold down accelerator for ten seconds, you should hear the water pump activate
I left cap open, he mentions it's up to you, I'd rather not use the screw there

Just let it cycle and if you're not sure, do it again

You don't ever ever want to open the coolant tank when the car is hot since it's pressurized.

After that warm the car up and see if heat comes out

Just figured I'd double check because I did exactly this twice. I bled it using this procedure when I did the swap and no dice :/

[kickthecan]

Originally Posted by whyyoumontague

Just figured I'd double check because I did exactly this twice. I bled it using this procedure when I did the swap and no dice :/

Try backflushing the heater core and doing it multiple times

Hoses may feel hot, but what do you have to lose ?

I think heating system isn't that complicated, coolant flows to the heater valve, then gets to the heater core, the core gets hot and air is blown through it and out the vents.

If there's some things clogging up the core, and trust me, you might see some gnarly things come out- I did on mine, it'll prevent the core from staying hot. Coolant may flow, but there may be debris in the core that prevents it from maintaining its heat

I don't think it's the heater valve since you said the hose going into the firewall and heater core gets hot

[whyyoumontague]

Originally Posted by kickthecan

Try backflushing the heater core and doing it multiple times

Hoses may feel hot, but what do you have to lose ?

I think heating system isn't that complicated, coolant flows to the heater valve, then gets to the heater core, the core gets hot and air is blown through it and out the vents.

If there's some things clogging up the core, and trust me, you might see some gnarly things come out- I did on mine, it'll prevent the core from staying hot. Coolant may flow, but there may be debris in the core that prevents it from maintaining its heat

I don't think it's the heater valve since you said the hose going into the firewall and heater core gets hot

Originally Posted by kickthecan

Try backflushing the heater core and doing it multiple times

Hoses may feel hot, but what do you have to lose ?

I think heating system isn't that complicated, coolant flows to the heater valve, then gets to the heater core, the core gets hot and air is blown through it and out the vents.

If there's some things clogging up the core, and trust me, you might see some gnarly things come out- I did on mine, it'll prevent the core from staying hot. Coolant may flow, but there may be debris in the core that prevents it from maintaining its heat

I don't think it's the heater valve since you said the hose going into the firewall and heater core gets hot

Sorry to revive, wanted this here for anyone who may stumble on this later. It was in fact a clogged heater core. Flushed today with hose and heat blows full hot again.

[kickthecan]

Originally Posted by whyyoumontague

Sorry to revive, wanted this here for anyone who may stumble on this later. It was in fact a clogged heater core. Flushed today with hose and heat blows full hot again.

glad it worked!

[arulthukral]

Originally Posted by whyyoumontague

Sorry to revive, wanted this here for anyone who may stumble on this later. It was in fact a clogged heater core. Flushed today with hose and heat blows full hot again.

Im facing a very similar issue and its driving me nuts. Can you tell me how you flushed the heater core?

[kickthecan]

Originally Posted by arulthukral

Im facing a very similar issue and its driving me nuts. Can you tell me how you flushed the heater core?

You remove the heater core hoses from the two inlets at the firewall going into the heater core.

If it's a quick and easy flush, try to angle the hoses vertically so more coolant doesn't drain from the engine and try to tuck it somewhere while you deal with the heater core.

I believe you need 3/4 ID hoses for the heater core so grab some of that and a bucket. You need a water hose adapter. If you watch chrisfix's heater core video, he shows an overview of the process since it's pretty much the same for every car now.

Connect hoses to the heater core. Connect the water hose into the heater core outlet and slowly release water from the hose. I'd suggest a valve there or something. Water will flow against the normal flow of the heater core...hence backflushing it. Let it run for a few mins then stop and pulse the water. Once it looks clear, switch hoses and flow the water the normal way and keep switching back and forth until you feel comfortable with how clear it is.

Once that's done, blow into the hose to empty out as much water as you can from the heater core and pour down distilled water into the heater core. Once it's full and distled water is draining out one end, reconnect the cars heater core hoses.

Then trigger the water pump bleeding procedures...run it twice. Make sure you don't see any bubbles in the coolant tank and you should be good to go.

I'd just YouTube BMW heater core instead since it's pretty much all the same