328 Heater questions / do they all do this

For problem #2 my 1987 did that, and so did a friends 1989. Never figured out the solution. All I could think of was that the water pump is not moving the water with enough pressure to get the hot water moving through the two heat exchangers up front....once you get moving the pump is moving faster...so it starts working. I wonder if the heat exchangers have some obstruction or are slightly plugged up? I know in my instance the water pump was newly rebuilt, and the radiator had been rodded out (brush run through all the tubes in the radiator).

 

I thought I read about this, but not sure. You may need to bleed the system.

 

Never had number 2 happen to me (perhaps you may want to rev the engine while stopped to see if the water pump needs to be urged to do its thing, if that gets the heat going it's a circulation problem, could be a clogged or partially clogged heater core). As to number 1, mine starts but in order to get meaningful air circ. you do have to turn the knob a fair amount. I assume that's what you meant.

Alberto

 

Most likely that the contacts of the variable resistors (adjusted by turning the knob) have some dirty spots in the section for lower speeds. Or, maybe the fan motors bearings are dryish and need more voltage to get spinning because of the higher than normal mechanical resistance.

 

I never had similar problems n my '86 Euro.

Ciao

Eugenio

 

I had a 86 328 gts black /white and problem nr 2 is famous because:

The engine temp is lowered till 70 degrees celsius with a front engined car it is 85
So when the heater is working the temperature coming out will be sustainibly lower because of the 15 degrees diffrence in temp of the heating radiator
The engine temp is dropped because the engine is mounted in th e rear of the car against the firewall so it isn't cooled by the driving wind
Thats why theydropped the temp
Another cuase is the capacity of the water pump at idle speed, its not enough both ways, I will explain
In the winter you have to rev up the engine to at least 3000 rpm to transfer hot water from the engine to the front off the car where the heating radiator is lokated.
In the summer when the car is in traffic and its really hot the engine temp gets too hot and the cooling radiator in the front is cold and the fans aren't working
Same problem, so rev it up and you will see temp going down and fans starting to blow
Maybe you can add a electrical waterpump in the heating circuit thats what at least I was thinking off
I hope I answered your question

 

I also thought that the fan switch may be the cause of the fans not working until turned up a way. However, I don't see how to open the switch up and clean any contacts without breaking the switch. I pulled it last night as I'm removing the interior of my 328 and it seems like a sealed unit. Has anyone done this?

 

My 328 is like that, but I never thought I had a problem. I thought the fans were two speeds.. low and high. The control doesn't have detents, so it is off then on 'low' and then on 'high' depending how far the knob is turned.

 

Mine works fine on both knobs. Slowly turns up to the fastest speeds. I was just hoping the OP would be able to clean the contacts inside the control.