1981 928 heat issue
11-28-2010, 10:48 PM
#1
3rd Gear
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Join Date: Nov 2010
Location: Ohio
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1981 928 heat issue
Hey Guys,
I have a 1981 928 that I bought a few weeks ago. I have been driving it around mostly on nicer days recently and for the first time drove it last night when it was pretty cold outside only to realize the heat is not working properly. Air will blow out of the vents and it is cold on the passenger side and middle vents and only slightly warm on the drivers side. I am not sure where to start looking for the problem. Any advice/help is much appreciated.
I have a 1981 928 that I bought a few weeks ago. I have been driving it around mostly on nicer days recently and for the first time drove it last night when it was pretty cold outside only to realize the heat is not working properly. Air will blow out of the vents and it is cold on the passenger side and middle vents and only slightly warm on the drivers side. I am not sure where to start looking for the problem. Any advice/help is much appreciated.
11-28-2010, 11:01 PM
#3
Rennlist Member
A not uncommon fix for excessive heat caused by loss of vacuum to the heater control valve (or the valve diaphragm is ruptured) is to cable tie the tap closed. This tap is on the rear of the rhs head, under the air cleaner casing. Remove the top of the air cleaner, and check the tap under the lower casing- an arm is supposed to be able to operate by applied vacuum....Its alos possible the hose from the tap to the heater core has failed and been plugged or bypassed.
jp 83 Euro S AT 52k
jp 83 Euro S AT 52k
11-28-2010, 11:13 PM
#4
Team Owner
you would be well served by following Wallys HVAC system diagnosis its at 928gt.com on page 2 under tips and links.
You probably have one or more failed vacuum pods and they could be causing the heated air from being circulated.
As has been previously posted ,
you need to inspect the heater control valve,
if its older than 5 years it would be wise to replace it ,
as well as the short hose that connects it to the head outlet.
Also you might try putting the temp selector to full hot this will override the auto temp system and give full hot.
Make sure the coolant bottle level is at the mark just above the center seam.
Note there are micro switches in the full cold and full hot positions of the slider track,
they take the temp sensor string out of the HVAC loop.
There is also a good possibility that you have a broken sensor string,
usually the failed part is the outside sensor,
its usually a bad wire connection under the left headlight.
Wallys info will guide you though
You probably have one or more failed vacuum pods and they could be causing the heated air from being circulated.
As has been previously posted ,
you need to inspect the heater control valve,
if its older than 5 years it would be wise to replace it ,
as well as the short hose that connects it to the head outlet.
Also you might try putting the temp selector to full hot this will override the auto temp system and give full hot.
Make sure the coolant bottle level is at the mark just above the center seam.
Note there are micro switches in the full cold and full hot positions of the slider track,
they take the temp sensor string out of the HVAC loop.
There is also a good possibility that you have a broken sensor string,
usually the failed part is the outside sensor,
its usually a bad wire connection under the left headlight.
Wallys info will guide you though
