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914World.com _ 914World Garage _ Rear Heater Blower Motor
Posted by: LotusJoe Feb 21 2012, 06:25 PM
I'm installing the rear blower motor. Mine only as one outlet. I'm assuming this is because it had air conditioning. 
The parts book only list one blower motor, but it has two outlets, although the parts number on my blower matches the one in the parts book. 
914 rubber shows a blower with two outlets as well, but different from the parts book??
Posted by: SLITS Feb 21 2012, 06:35 PM
The early cars had a two outlet blower which Porsche/VW deemed not necessary. The went to the single blower and fed one HE.
There is a splitter that attaches to the blower in place of the plastic nozzle that will allow you to run hoses to each HE, which is your bottom image.
Posted by: LotusJoe Feb 21 2012, 07:01 PM
The early cars had a two outlet blower which Porsche/VW deemed not necessary. The went to the single blower and fed one HE.
There is a splitter that attaches to the blower in place of the plastic nozzle that will allow you to run hoses to each HE, which is your bottom image.
Then obviously, it's not necessary to route air to both heat exchangers. I think I like that better...the hose running across the engine looks like an after thought and a PITA. Thanks!
Posted by: McMark Feb 21 2012, 07:21 PM
There were three stock setups for the auxiliary heater fan. The early version (70-72 IIRC) was mounted on the engine itself and the early cars do not have a mount on the chassis.
In 73 they started mounting the fans on the chassis and used a single outlet fan in 73-74 because they figured that the air coming out of the engine fan that gets directed through the heat exchanger was sufficient for passenger comfort. The fan in those years was intended to boost the defrosting of the windshield for the driver. In these cars there is a factory supplied plastic cap that covers the passenger side aux. fan pipe.
In 75-76 they added a 'splitter nozzle' to the same 73-74 fan and boosted both heat exchangers. Note that it's the same fan, so the 73-74 cars were blowing all that air out one side, and the 75-76 cars split that air in half.
Also, worth clarifying for some silent readers, that the aux fan mentioned/pictured is only for boosting the air through the heat exchangers. All cars have a fair amount of air coming from the engine fan at all times, which will supply heat through a completely stock system. Also, if you don't have a fan connected to one or either of the aux fan pipes, you should plug them. Otherwise you'll lose some of the air pressure from the engine fan.
Posted by: Prospectfarms Feb 21 2012, 07:30 PM
...Also, worth clarifying for some silent readers...
One of the silent readers says, "thank you."
Posted by: brainf18 Jan 29 2020, 07:57 PM
dumb question but I'll ask b/c its cold outside and i want heat. The blower motor mounted on the firewall isn't coming on. but when turn on the "fan" switch I can hear a blower coming from under the dash. I assume both blower motors should activate?
Posted by: Jett Jan 29 2020, 08:07 PM
dumb question but I'll ask b/c its cold outside and i want heat. The blower motor mounted on the firewall isn't coming on. but when turn on the "fan" switch I can hear a blower coming from under the dash. I assume both blower motors should activate?
There are two actuators. To turn on the rear fan, pull up on the switch/lever with the red plastic top, that is located behind the shifter.
Posted by: brainf18 Jan 29 2020, 08:29 PM
dumb question but I'll ask b/c its cold outside and i want heat. The blower motor mounted on the firewall isn't coming on. but when turn on the "fan" switch I can hear a blower coming from under the dash. I assume both blower motors should activate?
There are two actuators. To turn on the rear fan, pull up on the switch/lever with the red plastic top, that is located behind the shifter.
thx...tried that. Not working. Time to trouble shoot
Posted by: rhodyguy Jan 29 2020, 08:58 PM
You have to set the dash controls so the fresh air box is closed. Check the wire on the red handled lever. The lever must be fully raised to activate the fan and it also opens the Heat valves. The aux fan is only of any assistance while idling. Capping both J tubes, decent heat exchangers and a sealed ducting system will provide ample heat.
Posted by: Rob-O Jan 29 2020, 08:58 PM
dumb question but I'll ask b/c its cold outside and i want heat. The blower motor mounted on the firewall isn't coming on. but when turn on the "fan" switch I can hear a blower coming from under the dash. I assume both blower motors should activate?
There are two actuators. To turn on the rear fan, pull up on the switch/lever with the red plastic top, that is located behind the shifter.
thx...tried that. Not working. Time to trouble shoot
It’s a pretty basic switch. Usually it’s just got some corrosion and isn’t making a good ground where the handle is attached to the body of the car.
Posted by: SirAndy Jan 29 2020, 09:37 PM
Posted by: maf914 Jan 30 2020, 07:41 AM
You have to set the dash controls so the fresh air box is closed. Check the wire on the red handled lever. The lever must be fully raised to activate the fan and it also opens the Heat valves. The aux fan is only of any assistance while idling. Capping both J tubes, decent heat exchangers and a sealed ducting system will provide ample heat.
Rhodyguy is correct. When the heat control lever is raised the initial motion pulls the cables which gradually open the heat control flaps at the heat exchangers. When the flaps are open the last lever motion makes contact which turns on the fan in the engine bay to boost the airflow through the heat exchangers.
Posted by: johnhora Jan 30 2020, 11:58 AM
Here's some pics of the early engine mount bracket for the blower.
It bolts onto the driver side of the engine fan housing
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