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Mitch Leland's Avatar
 
Join Date: Apr 2007
Location: Fredericksburg, Texas
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Has anyone installed rennaire's trinary switch

I purchased Rennaire's Trinary A/C 2 pole pressure switch from Pelican Parts with installation instructions. When I talked to Rennaire I was under the impression that it was a hi/lo pressure switch, now I don't think so... Has anyone installed this switch?

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Mitch Leland
"03" 996 C2S-LS3 V8-480 HP
"84" 911 Turbo Look-Sold w/ found memories
Old 07-25-2009, 10:57 PM
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I recently installed a trinary switch that attaches to a T fitting from the high pressure port of the compressor. The trinary switch has a low pressure cutoff if refrigerant gets too low. It has a high pressure cutoff if system pressure gets too high and also a feature that turns on an electric fan when pressure raises to a point that the fans will help cool the condenser. If the condensers have good airflow and thus lower high side pressure, then the fans will be off. When the high side pressure goes up to a certain point, the switch activates the electric fan(s) to blow air on the condenser(s). If you don't have fans then you can still use the switch as a high-low cutoff. Splice the switch between the compressor and the wire that powers it. You will use only 2 of the 4 wires. At a later point if you need more cooling, the trinary switch will already be installed so you can use the two extra wires for the fans without having to evacuate and recharge the system to install the switch.
There is a wiring diagram available at www.nostalgicairparts.com under the tab "instructions"
Old 07-26-2009, 05:14 AM
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Rennaire's trinary switch...

Jet Jockey,

Thanks for the reply... It's interesting after visiting the link that you put up that their schematic and Rennaire's schematic is the same. So I'm not use whether someone has sat down and reviewed the Porsche schematic to see if the two are compatible.

Do you believe that you have "low pressure" protection? I'm not sure that you do? Do you have a one or two pole switch? Where did you intercept the green condenser wire?

I was told that my switch would install on the high side Schrader valve at the compressor. I installed the Trinary switch at that location, and made temporary connections interrupting the green wire to the compressor clutch.

I had two problems with this set up. One, the engine had a slight buck at cruise, the other the A/C compressor clutch was doing something funny since I had shards of rubber on the motor mount. Bottom line is that I think you have to connect the green wire forward of the "jumper connection" as shown on Bentley's schematic. I'm nearly at a point of evacuating my system and putting the switch in the smugglers box, thus saving having to run wires from the engine room forward.

Sorry for the long drawn out story... On going story at best.
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Mitch Leland
"03" 996 C2S-LS3 V8-480 HP
"84" 911 Turbo Look-Sold w/ found memories
Old 07-27-2009, 09:05 PM
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I may be wrong but the way I understand it, the fan(s), if installed, will turn on when high side pressure reaches 250 psi. The compressor will shut off if high side pressure goes above 405 psi or below 30 psi. I wired the trinary switch at the 'slide connect' about 6 inches from the compressor. The green wire goes to the trinary switch and power exits the trinary switch to the red compressor wire. When installing additional fans I was told not to use the green wire as a power source.
I am also getting a slight rumble when the A/C is turned on. I changed from the Nippondenso to a Sanden 709 and attributed the different sound to a new compressor.
Old 08-02-2009, 08:54 AM
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Jetjockey,

I've had some really smart people look at Rennaire's schematic and lay it over the Bentley's schematic and they say it doesn't work that way. Yes it has a compressor high side cut off, but it will not shut off the compressor with a low side failure. The "rumble" I believe is a DME feed back from the circuit. To avoid this you have to make your connection forward of the "jumper connection". See Bentley's schematic. To confirm this undo your Trinary switch connection and the rumble will go away. Or just turn your A/C off and I bet the engine rumble goes away.

Rennaire@info has not returned my e-mail, I'll try and call them this week to see if I can get any more information on the wiring of their switch.

Bottom line I think our A/C system needs at the very minimum "high side" pressure protection, it would be nice if it also had the low side protection as well. I think or wish that I would have included the hi/lo safety switch into my original upgrade at the evaporator, smuggler's box area when the work was done a year ago.

My present plan is to fine a location between the ProCooler/drier and the evaporator to install the Trinary switch. Connect into the wire that comes out of the relay feeds the condenser blower.

Stay tuned, film at eleven...
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Mitch Leland
"03" 996 C2S-LS3 V8-480 HP
"84" 911 Turbo Look-Sold w/ found memories
Old 08-02-2009, 09:41 AM
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Old 08-02-2009, 09:41 AM
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