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Do the Ob’s have the relay that is replacable on the head unit like the later cars? Here’s a pic of mine, it’s quite different than the later cars described in all the relay replacement threads. Thanks in advance
Last edited by Oldewoodupes; 06-15-2018 at 05:08 PM.
no relay - the red unit in second photo is a simple on off switch for compressor. The rest is controlled by simple electrical trace board, metal quadrants that control the vacuum module for the various valves.
no relay - the red unit in second photo is a simple on off switch for compressor. The rest is controlled by simple electrical trace board, metal quadrants that control the vacuum module for the various valves.
thanks jwillman. Do you know if there is an equalivalent relay to what people have been replacing in the later cars in the OB’s circuit somewhere else or was it something Porsche added later to the circuits?
I recall a couple threads on this topic in the past. I would like to add a relay to mine as well, but I need to replace the compressor and upgrade to R134a first. So I have not tried this, but the ideas seem logical to remove the current from the control head. Here is a link to a thread on this topic:
06-15-2018, 01:37 PM
78 OB HVAC control head relay?
