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Can someone help me with trouble shooting my Daikin VEF

Customer Question
Can someone help me...

Can someone help me with trouble shooting my Daikin VEF system?

Contractor's Assistant: I'll do all I can to help. How long have you been dealing with this?

This is an HVAC system

Contractor's Assistant: Are you an HVAC professional?

Yes

Contractor's Assistant: Do you plan on doing the work yourself?

I am getting a fault code of U4 at the master tgermostat

Contractor's Assistant: Anything else we should know to help you best?

Don't understand your question

Submitted: 9 months ago.Category: HVAC
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Customer reply replied 9 months ago
Who is helping me?
Customer reply replied 9 months ago
I just paid my $$
Customer reply replied 9 months ago
Is anyone out there?
Answered in 5 days by:
9/22/2017
HVAC Technician: MattR757, HVAC Technician replied 9 months ago
MattR757
MattR757, HVAC Technician
Category: HVAC
Satisfied Customers: 67
Experience: 18+ Years experience in residential and commercial HVAC service and repair
Verified

Sorry noone responded sooner.

U4 is a communication error between indoor and outdoor units - Make sure that power is on to both units and reset power to both to clear stored errors - Depending on how it was installed, sometimes an external components like a condensate float switch or a smoke detector may be wired into the communication wiring chain and will break communication - check any drain pans for water and look at the wiring to make sure there isn't any damage (landscapers are notorious for damaging outdoor wiring with their weed eaters).

Aside from that you could have a bad board or a dropped address (communication glitch that disconnects the indoor unit from the com loop) and might need a Daikin tech to come investigate.

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Customer reply replied 9 months ago
I was getting U4 when the system was running off of my emergency generator as a consequence of Hurricane Wilma. Now that permanent power is back up, I am now getting a U7 error code! AHU's are all running as we resent power to all of them, as well as the CU, but no cooling as the CU is not kicking on! Thx...Rich Housh...old energy guy and former HVAC technician
HVAC Technician: MattR757, HVAC Technician replied 9 months ago
U7 error is no communication between the main pc board and the inverter pc board inside the outdoor unit. Almost always means that the inverter PCB is bad. I'm not 100% sure, but I may still have a copy of a Daikin service manual that goes through steps on how to test the board and compressor. I will message you back once I get back to my office to check
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HVAC Technician: MattR757, HVAC Technician replied 9 months ago

Here is the service manual for VRV III - The VEF units are Vicot European fan coil units and I do not have any manuals for those specifically. This manual is huge, but has a really well organized troubleshooting section and a lot of very specific test procedures outlined in it. Hope this helps some -

https://drive.google.com/file/d/0B5ej3CaCXvZiTVpBcVpjZTBmcWM/view?usp=sharing

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