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Category: HVAC
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Experience:  15yrs in the HVAC industry with certificates and degrees.
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I would also like to know what the issue was with Err 90

Customer Question

I would also like to know what the issue was with Err 90 showing up on the thermostats. I have that issue on all thermostats connected to a Honeywell EnviraZone W8835A1004 zone control panel. This error is for continuous communication on the EnviraCom serial bus (three wire) that the thermostats communicate on with the control panel. I am going to attempt to debug this by disconnecting the thermostats from the panel and doing a local short connection to the control panel with Thermostat #1 just in case the problem is with the wire. If the error still comes up then it is most likely the panel circuit board I am guessing. I am just curious if anyone has actually fixed this error somehow with it not being the board.
Submitted: 1 year ago.
Category: HVAC
Expert:  HVAC Guru replied 1 year ago.

Hello and thanks for using this service, if you have been waiting do not worry or get upset. I am APPLIANCE-HVAC GURU a very experienced tech on here and I try to get to as many customers as I can. I just picked up your question now.

Please allow time for me to respond, sometimes I get the questions or responses late so please be patient as I have no control over the site issues. NOTE, I have nothing to do with your payment to the site and did not receive that money.

You are right on track, do the short connection and if it comes back replace the control panel. That is all that can cause that error it may have fired or had a voltage spike damaging it. If you need anything else let me know.

The only way I receive any credit at all for my time is by you selecting a STAR USING THE 5 STAR or VOTING RATING SYSTEM AT THE TOP OF YOUR PAGE before you leave for me so please make sure you are rating me not another tech. If you are not happy with the service please let me know before leaving a negative rating. This will also allow you to get directly back to me for FREE follow up questions and tips are greatly appreciated! Thanks GURU

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