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#1
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trouble shooting the switch control unit
hello all,
so I am not getting any juice to the compressor.... here's what I have done so far. this is a conversion to 143A and so have flushed the system and replaced the compressor, the switch control unit (but it was a used one!! ![]()
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Thanks! Scott sdpettitt@yahoo.com |
#2
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compressor works fine
oh, forgot to mention, the compressor works fine and is hooked up correctly. with the engine off I con take a lead directly from fuse 8 to the compressor and I can hear it click on loud and strong, so that is not the problem. the problem is before the compressor, before the pressure switch, before the ETR valve....
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Thanks! Scott sdpettitt@yahoo.com |
#3
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hey does anyone know if the A/C compressor relay is before or after the pressure switch? that might shed some light on whether it is the relay or something else. I am thinking......... or trying to.......
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Thanks! Scott sdpettitt@yahoo.com |
#4
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The compressor relay coil is powered through the evaporator temp switch. Power to the compressor comes directly from a fuse.
Sixto 95 S420 87 300SDL |
#5
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thanks for the info,
so where does the power to the evap temp sensor come from? I am not getting any power to that switch. so starting at the end this is what I am picturing. power to the compressor comes directly from fuse 8. control of the compressor comes from the pressure control switch on the receiver which in turn comes from the ETR (evaporator temp) switch under the dash but where does it come from before that?? thanks Scott
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Thanks! Scott sdpettitt@yahoo.com |
#6
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In defrost, total ventilation and normal modes the PBU sends +12V to the ETR which opens below 40*F.
Sixto 95 S420 87 300SDL |
#7
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" control of the compressor comes from the pressure control switch on the receiver which in turn comes from the ETR (evaporator temp) switch under the dash but where does it come from before that??
From the " ON " button on the AC controls ? |
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