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View Full Version : Carrier Multi VRF prob.-not communicating?



twisty
17-04-2007, 11:42 PM
Hi Guys + Gals,Just stumbled across this site and wondering can anyone help with a misbehaving Carrier VRF model38VVH25 O/D, 38VV9003 Gas Flow Distributors(X2) with 4 indoors (voids) on each GFD.
Problem is no signal sending or recieving from unit A on either GFD even though new expansion boards fitted.
no fault codes up and temp sensors can be read on all units from GFD's LED display so it appears to be communicating to some extent.
any thoughts?

Loops
20-04-2007, 11:08 AM
Hi Twisty,

Wow this is going back a few years , these are a two pipe R22 heat pump VRF system.

They are highly modified Toshiba systems made (by Toshiba for Carrier) just about when Toshiba \ Carrier merged. The GFDs were modified to communicate (via an additional board) with standard Carrier indoor units.

I seem to recall that you had to be very careful which Carrier version indoor board was fitted. Early ones didn't work.

In the GFD - If you put the white rotary dial to zero you get a display for system comms. Correct display is HH for four indoors or Hh for three. The vertical lines are to \ from the indoor units A-D left to right. the horizontals are to \ from outdoor.

The original Toshiba pcb (with yellow and white dials) is very reliable for communication so I doubt that's the problem.

Start by trying a new indoor board but get the correct generation board. If no luck maybe the left board in the GFD has packed up.

No idea if spares are still available though - talk to you local Carrier agent or Carrier directly.

Sensor data is available because the std PCB (right hand one) is reading the internal GFD sensors - not indoor unit sensors.

Let us know how you get on.

Cheers

Loops

twisty
20-04-2007, 11:25 PM
:Thanks 4 the info Loops,tried a new indoor Main board as well as the expansion board and that unit is finally communicating,awaiting second board from Carrier which should sort it out.

Incidentally, found a possible cause- electrician had wired in mag-lock on reception door to same spur as indoor unit,probably causng spikes and surges.

Regards,
Twisty

Loops
23-04-2007, 08:19 AM
Hi Twisty,

Always good to know how a site is progressing. Glad to hear you're on the right road to fixing it. I'm thinking the indoor board is most likely culpret, I had a few failures on commissioning these systems back when they were new.

Yes the mag switch could be causing a problem I guess - I've not seen one used so a little vague.

Cheers

Loops