88 S4 A/C and more questions
09-12-2013, 04:40 PM
#31
Drifting
Thanks, I have a vacuum gauge lying around and have no objection to getting a new heater valve. I'm just wondering if there is a heater door behind the dash that would switch between the a/c and heater core.
I'll check tonight or tomorrow and report back. Thank you all for your input.
I'll check tonight or tomorrow and report back. Thank you all for your input.
I second Dr. Bob's comment about leaving it tied shut during the summer. A quick stop for a soda pop can result into a warmed heater core that has to be cooled off all over again.
09-12-2013, 10:20 PM
#32
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Gentlemen,
First of all, thank you for your comments and advice here. I stopped by my wholesaler and bought a heater valve on the way home but it appears that I don't need it. Following the most recent updates from the thread, I decide to chase the vacuum line back near the master cylinder and sure enough, one of the vacuum hoses on the 4 way connector was disconnected. I cranked the engine and watched the heater valve shut so I turned the a/c and got cool air from the front.
It's not always this easy, but it really is nice when it is.
I'll put the heater valve on the shelf for a while and switch it out when I have a little more time. Right now my other shark project (BMW M6) is needing some love so I'll spend my weekend on it while I drive this beast.
First of all, thank you for your comments and advice here. I stopped by my wholesaler and bought a heater valve on the way home but it appears that I don't need it. Following the most recent updates from the thread, I decide to chase the vacuum line back near the master cylinder and sure enough, one of the vacuum hoses on the 4 way connector was disconnected. I cranked the engine and watched the heater valve shut so I turned the a/c and got cool air from the front.
It's not always this easy, but it really is nice when it is.
I'll put the heater valve on the shelf for a while and switch it out when I have a little more time. Right now my other shark project (BMW M6) is needing some love so I'll spend my weekend on it while I drive this beast.
09-12-2013, 11:37 PM
#33
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No heater door... all air flows through both evaporator core and heater core then directed by a gate to blow floor, face, defrost. IIRC, A/C is all or nothing, where heat is added to modulate temp. Somewhat related obscure bit of trivia, some (maybe all) defrost systems engage A/C even in the winter to "dry" the air it's warming....
Defog (DEF) systems use AC and max heat - you will defrost faster without AC for obvious reasons. To defrost fast set max heat, fan and defrost vent, close center console & door vents - don't use DEF (thats not what its really for). Heating cold air allows it to hold more moisture.
Easiest to say when the AC is on - the system runs continuously unless the evaporator freezes up, the temperature control is still via the heater core & mixing flaps as with pure heating. So when the temperature is set to other than max cooling the comb flap may disengage when it needs to warm up the cabin air..
Alan
09-12-2013, 11:42 PM
#34
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