Community Forums

Mlfiedler · 02-07-2021, 03:50 PM

I’m trying to finess an electronic replacement for the Sauer Danfoss hydraulic fan controller along the lines of what CC Rider / RonandSue74 posted about back in September. https://www.irv2.com/forums/f112/sau...on-501809.html

That uses a PWM speed controller to set a speed between slow, and wide open. But I’m hoping add a relay triggered by a tie into the trinary valve of the OTR A/C, to boost fan speed when the A/C kicks on.

My trinary valve has four wires out of the valve, but two of those connect to a single wire 4” away. So I’m imagining this is the hot side of things, and the other two should be NC-switched, one to the compressor, and one to the fan controller. Both are black. HBut then they all disappear into a thick bundle of wires in the wrapped and bound loom of wires!

So I thought I’d identify the fan boost line, by excluding the compressor wire. A single wire exits the loom at the compressor, but I cannot detect continuity to anything running to the trinary!

Is there something else, like a relay, between the trinary and the compressor? Any idea WHERE? Anyone have a schematic for this? I’m stalled.

Mlfiedler · 02-07-2021, 05:15 PM

Thought I could I.D. the wire I need from the other end. Maybe.
At the Sauer Danfoss fan controller, there are 8 wires entering the control box. Two pairs were identified as pickups from the SD temp thermistors in the coolant and CAC. These are the blue and gray pairs, twisted together. This leaves a red-green pair, and a purple-yellow pair. This last is in a connector block with the temp sensor lines, but red-green has their own connector. Is this the A/C boost signal line? Is the red-green owner?

As noted above, wires from the Trinary are Black.

TR4 · 02-08-2021, 09:05 AM

Do you still have your binder that originally came with the coach? They have wiring schematics in it. About three years ago I moved my a/c dryer and condenser to the front. The trinary switch was connected to the dryer. I know there were one or two relays in the dash (passenger side). The wires from trinary (original area) came from the back up to the relays in the front.

Couldn’t you just take a signal off the compressor? You also have to address how to activate the fan when intake air temperatures rise, you can get an engine shut down. I’ve found the wax valve to be a lot less complicated.

PM me if you don’t have the schematic, I’ll try to go over it with you.

Bill

Mlfiedler · 02-08-2021, 11:34 PM

Quote:

Originally Posted by TR4

. . . Couldn’t you just take a signal off the compressor? . . . PM me if you don’t have the schematic, I’ll try to go over it with you.
Bill

Wow! Perfect solution!

Can't believe I wasted all that time trying to figure out how the "signal" was going to be sent to the compressor, when its right there for the taking! Duh!