Replaced heater core, now only warm air

trillogy · Post by **trillogy** » 16 Dec 2011, 03:52

I have a 1993 850 with climate control. The heater core went out and so I replaced it. Now the cabin air is not as hot as it used to be coming in. It is warm, but not like in the past.

Both hoses coming to the heater are hot. The tempature gauge shows properly at around 3 o'clock.

I am wondering if there is a damper for the air mix that I might have moved when replacing the heater core?

Post by **precopster** » 16 Dec 2011, 04:50

The aftermarket heater cores are well known to have greater spacing between the cooling fins and therefore lower thermal loss making them poorer heater cores than the OEM or Behr brand.

When you received the heater core did it come packaged with two seals? If so it's the same core sold by all the aftermarket resellers. Only the Behr brand which is the OEM manufacturer produces the same heat as the original core (and is supplied without the two o ring seals.

Post by **rspi** » 16 Dec 2011, 08:51

You could have a little air trapped in there. Give it a week to work out the air.

trillogy · Post by **trillogy** » 18 Dec 2011, 16:08

@precopster. I have looked into the aftermarket versus OEM cores. When this one came, I measured the size, shape and number of fins and such. It is/was fine. But, thank you for gving thought to my issue.

By the way, thank you very much for an excellent article about replacing the heater core. I really appreciate the effort you put into it.

@rspi. It's been around 3 weeks. I have taken the top off the expansion tank several times. I added a small amount of coolant once, since then it's been pretty much the same.

The air is warm, just not quite as warm as before. I am still wondering about the damper flap that adjusts the outside mix with the air.