fresh air only?
10-11-2011, 12:20 AM
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Location: Tucson, AZ
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fresh air only?
Sorry in advance for this possibly stupid question but is there a HVAC setting that simply lets fresh air in without attempting to thermostat it? Yes, yes I know, roll down the windows. The coolest setting on the dash is 65, but that was heating our unseasonal fifties air last Sunday morning so . . .?
John
'88 S4
John
'88 S4
10-11-2011, 02:19 AM
#2
Nordschleife Master
Sorry in advance for this possibly stupid question but is there a HVAC setting that simply lets fresh air in without attempting to thermostat it? Yes, yes I know, roll down the windows. The coolest setting on the dash is 65, but that was heating our unseasonal fifties air last Sunday morning so . . .?
John
'88 S4
John
'88 S4
Where I live the ambient air is often cool, and what comes through when I have fresh air coming in reflects the temperature outside. I have to open up the heater valve a little to warm up on cool summer mornings.
Drive the car with the temp on coolest for a while. You will get a warm air blast on a restart for the heater valve vacuum fades on turn off allowing hot water into the core. If you still get warmer than expected air through your vents it is the heater valve / vacuum to it problem.
03-08-2012, 01:44 PM
#3
Electron Wrangler
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The owners manual really doensn't tell you much here aside from most basic operation.
The real truth is that temperatures a little above 65F are controlled temperatures a little above 65F.
But full left 65F is NOT 65F - it is as cold as it can get = Max Cooling - there is a limit switch for this.
In this mode (when everything is working - yours obviously isn't) the water valve for the heater core will close, the mixing flaps will close completely (fully bypassing the hater core), the comb flop will further bypass the heater box and outside temp air will be unheated.
Exceptions to this are recirculate mode (only a few % is external fresh air) and AC mode - incoming air will be further cooled by the evaporator to as cold as it can get.
Similarly at the very hot end there is limit switch for Full Heat. In this mode the water valve is opened and the heater mixing flaps are opened fully, the comb flap ensures full heater box flow and the HVAC will heat as much as it can, AC on will limit this a little and it will be hotter still on recirculate mode.
This will quickly become unbearably hot in a correctly functioning, warmed up vehicle in anything other than extremely cold ambient temperatures.
Seems most likely that your water valve has failed or leaks. Pretty easy fix.
Alan
The real truth is that temperatures a little above 65F are controlled temperatures a little above 65F.
But full left 65F is NOT 65F - it is as cold as it can get = Max Cooling - there is a limit switch for this.
In this mode (when everything is working - yours obviously isn't) the water valve for the heater core will close, the mixing flaps will close completely (fully bypassing the hater core), the comb flop will further bypass the heater box and outside temp air will be unheated.
Exceptions to this are recirculate mode (only a few % is external fresh air) and AC mode - incoming air will be further cooled by the evaporator to as cold as it can get.
Similarly at the very hot end there is limit switch for Full Heat. In this mode the water valve is opened and the heater mixing flaps are opened fully, the comb flap ensures full heater box flow and the HVAC will heat as much as it can, AC on will limit this a little and it will be hotter still on recirculate mode.
This will quickly become unbearably hot in a correctly functioning, warmed up vehicle in anything other than extremely cold ambient temperatures.
Seems most likely that your water valve has failed or leaks. Pretty easy fix.
Alan
