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It's the red with a white stripe and the violet with a yellow stripe, wires 5&6
Is the switch that is circled the a/c switch? If it is, it looks like they were trying to bypass the a/c switch/button. Is the a/c button a double throw, double pole switch?
Is the switch that is circled the a/c switch? If it is, it looks like they were trying to bypass the a/c switch/button. Is the a/c button a double throw, double pole switch?
What you've circled in the diagram of the HVAC head is the internal relay. The actual push button switch is up and to the right in your picture of the wiring diagrams.
Since the 2A internal relay in the HVAC carries a 3A load, failure of the relay is a typical/common/happens-eventually failure mode.
So.... without looking further on the rest of the wiring diagrams, my guess is that the PO was trying to bypass the (dead) HVAC head relay.
What you've circled in the diagram of the HVAC head is the internal relay. The actual push button switch is up and to the right in your picture of the wiring diagrams.
Since the 2A internal relay in the HVAC carries a 3A load, failure of the relay is a typical/common/happens-eventually failure mode.
So.... without looking further on the rest of the wiring diagrams, my guess is that the PO was trying to bypass the (dead) HVAC head relay.
Agree that is what it is. Almost certainly the bypassed relay contacts are non functional (the other relay contact set is likely OK). This means AC is on only when the switch is on. The addition of the fuse was a nice touch - and although there is no longer a weak relay to protect - its probably still a good thing
The AC switch (top right) is indeed a dual pole single throw switch (DPST) AND so is the AC relay in the head unit - which is I think what you were actually asking about. The second contact set in the AC switch is used solely to control the illumination of the "AC" switch itself (on low with lights on and on brighter when AC engaged),
Note that the reason for the relay Vs. just the switch is that the head unit can turn the AC on even if the switch is off. e.g. during re-circulation mode to avoid windshield fogging and especially during selected "DEF" mode operation (the active defogging mode). This change defeats those safety features - though no more so than inoperative AC which is also quite common.
I believe the second contact set in the head relay is used to modify the behavior of the closed loop temperature control when AC is engaged. This is not a very significant effect.
A better fix would be to replace/upgrade the head unit relay - but still do keep a fuse in the circuit. This fuse would be better placed at the freeze switch for easier checking & replacement.
This was perfect. You guys are great. I'm going to use the write up by Duane and replace the A/C relay and solder up the wires to how they are supposed to be.
03-18-2020, 12:04 AM
A/C Wring by the P.O.
