Automotive Air Conditioning Information Forum (Archives)

Provided by

We've updated our forums!
Click here to visit the new forum

Archive Home

Search Auto AC Forum Archives

Compressor mounted high pressure switch

mckpaul on Wed October 10, 2007 3:42 PM User is offlineView users profile

Year: 1984
Make: Chevy
Model: C-10 Pickup
Engine Size: 305
Refrigerant Type: R134a

Would like to clarify the purpose of a compressor mounted high pressure switch.

I'm retrofitting my truck for R134a, doesn't have a high pressure switch at all right now, and my thoughts were to use a compressor mounted high pressure switch instead of the T-fitting, screw onto the high charge port retrofit kit. I'm seeing switches available that will CLOSE on high pressure.

1. Is the purpose of a compressor mounted high pressure switch typically to turn on an electric condenser fan?

2. Are compressor mount high pressure switches available that OPEN (to turn off the compressor) in the event of high pressure? (i.e. do the same function as the T-fitting retro kit?)

3. If I were to add an aftermarket condenser fan to come on if the high side pressure gets too high, do you still need a second high pressure switch to shut down the compressor, or will the additional air flow on the condenser be enough to keep the pressure down? (Seems like a "fan on" switch would be set at a slightly lower pressure than a "compressor off" switch.)

4. Is there a "one switch solution" available to do both functions, start a fan if needed, and then shut the compressor down if the pressure continues to rise? (Would be nice to put a switch in now, wire it in for cut off on high pressure, and have extra switch leads available if I wanted to add a condenser fan later)


iceman2555 on Thu October 11, 2007 9:57 AM User is offlineView users profile

Why not simply use something like this...available from works...minimum fuss...and does what is expected.

The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

NickD on Thu October 11, 2007 10:48 AM User is offline

The old way was to mount a high pressure relief valve that would blow it's cork if the high side pressure exceeded about 430 psi. Not to smart in my opinion as this would cost you a flush, new oil as you have no idea how much oil was also blown out, vacuum, and a fresh charge. All because maybe one too many insects plugged your condenser.

The electrical high pressure cutoff switch is connected in series with the cycling switch and should pop open if the pressure also exceeds around 390-430 psi that kicks off the compressor, these switches reset themselves if the pressure drops down in about the 200 psi range. So with the compressor off, no need to add extra fans, but time to check if your condenser is clean and the fan you already have is working properly. In your vehicle if you are converting to R-134a, would check into replacing your condenser with a parallel flow type. Hope this gives you some insight.

mckpaul on Thu October 11, 2007 2:49 PM User is offlineView users profile

Thanks for the responses guys.
Electrically, I'm up to whatever wiring I need to do, even if it meant adding relays to accomplish whatever, been doing low voltage stuff at work for years. One reason for the questions is the old original condenser. I've read where they may not be as efficient as the newer parallel type, and also read where adding an aftarmarket fan could help if needed if using an older style condenser. I also assumed to add a fan switch later (assuming I had already put the retro "T" fitting kit that iceman mentioned) that it would mean loosing the charge to add a switch to the compressor, so the thought came to mind to go ahead and put a switch on the compressor while it's not charged, all I'd have to do is wire up to it if needed later. And then the old brain, thinking of neat clean wiring and installation, said "Hey, wonder if they make a switch that does both?" So, I had to ask. My 2006 Torrent has two electric fans ahead of the radiator and condenser, one comes on with the AC. I guess, thinking more about it, worst case, if I did need a condenser fan later, I could just trigger it to come on any time the AC is on.

Yep, the system has been empty for a while. I actually pulled the condenser out, inspected it and straighened out all the fins and hosed it off. I plan to flush it and the evaporator before I start all this, and I have a new accumulator and expansion tube.

Probably will just do the "T" fitting kit for the high pressure switch. Guess it would make it more generic and easy for anyone that may be working on it behind me.

Back to Automotive Air Conditioning Forum

We've updated our forums!
Click here to visit the new forum

Archive Home

Copyright © 2016 Arizona Mobile Air Inc.