Jump to content

A/C question - high/low pressure switch wiring

Recommended Posts

Quick question about the A/C high/low pressure switch wiring. The eBay kit I purchased included a high/low pressure switch that has four wires: two blue and two black. See photo below:


If I understand how to wire the A/C system, that switch simply goes between the thermostat and the compressor.


CF6AB531-018A-4ABE-90B0-3DE9CF456D01-1601-000001E77A815C6B.jpeg.ea3f09b6f4038310e50ed2c795c19796.jpegThere's one wire from the thermostat and one from the compressor. So how do I use this pressure switch with four wires?



Link to post
Share on other sites

Update for future A/C installers.  It's not a binary switch (only two wires), it's a trinary switch (duh).  In addition to the high/low pressure shutoff for the compressor clutch, it also controls the electric fan in front of the condenser.  When the A/C system reaches 255 PSI, it tells the fan to turn on, thus cooling it down and lowering the pressure.  When the system is below 255 PSI, the fan stays off, saving some wear and tear.  


The Mini Kooler kit I'm installing (https://www.southernrods.com/a-c-and-heat-components/all-new-mini-kooler-ac-only-small-unit.html) doesn't include a relay, so I'll have to buy one from a local auto parts store.  Just a generic 30 Amp relay kit for like ten bucks should do it.  And in case anyone's curious about how to wire this up, here you go:




Probably common knowledge for most folks, but there's a first time for everything.



Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.