SeeTemp set LED blinking, HVAC controller does not trigger call for heat, or fan,

I have 3 SeeTemps and 3 wireless temperature sensors associated with an HVAC controller. (In another zone, I have one SeeTemp and two wireless sensors, and that one is still working).

All was working before today. Today, the room set (green) LED on the SeeTemps started blinking fast. According to the manual, that means there is a problem communicating with the wireless sensors. And although the Heat LED blinks slowly on each of the SeeTemps, the heat never comes on.

Turning the fan to "On", rather than "Auto", has no effect. The fan does not go on.

When I use the diagnostic tool in the RadioRA app, it reports no connectivity problems, but of course the temperature sensors do not support diagnostics.

I rebooted the HVAC controller by turning off the breaker to the air handler, waiting 30 seconds, and turning it back on.

Since the manual says that this blink pattern is related to communication with the wireless temperature sensors, in the software, I detached the 3 temperature sensors from the controller, re-attached them, and transferred the program.

If I put the SeeTemp in "Cool" mode, then "Fan On" works, and "Fan Auto" turns it off. However, even if I set the temperature to 60º, it does not call for cooling. On the other hand, if I leave it there long enough, the set light stops its fast blinking. (It starts blinking again after switching to heat and waiting.)

I know it seems like I've tried everything but looking at the HVAC controller itself. Well, it's in an attic crawl space that is hard to access, so I'm looking for everything else to try before I go up there. Is there anything else to try?

Thanks,
Bill

My ideas:

1- All working before today- no changes to OS or hardware, correct? For how many heating/cooling seasons has this system been working properly?
2- is the wired backup duct sensor installed?
3 - did you try replacing the batteries in the wireless temp sensor(s)?
4- can you try deactivating all 3 temp sensors, all 3 seetemps, and then activate just one of each?

I would say if the system doesn't respond properly with 1 seeTemp and 1 wireless sensor you'll need to dig out the HVAC controller and use the test modes to check HVAC operation. Then I would suggest bringing some Tstat wire and extending the HVAC controller leads to a location more service-friendly.

At the end of the day, the dip switches for system type were set wrong. It's a somewhat unusual hybrid air handler (for A/C and air movement) plus boiler 2-transformer setup, with hot water circulating to the air handler to go through a heat exchanger. The installer set the switches to Off/Off as shown in "Conventional Gas/Oil Heat System: 1 stage heat / 1 stage cool, 2 transformers" (since the boiler is gas-fired), but the working setting was Off/On as shown in "Conventional Electric Heat System: 1 stage heat / 1 stage cool, 2 transformers".

Interestingly, cool mode worked fine (including selecting On/Auto from the SeeTemp) even though switch 1 was off; it was only once the heating season began that the mistake was noticed.

I don't know what made the SeeTemp set light blink; I don't know if there is anything that the HVAC controller can detect about this misconfiguration that it was trying to hint at. After setting the switches properly and power-cycling the HVAC controller, everything seems fine (no blinking, heat and fan go on when desired).

Thanks for throwing some ideas out there, digit1; I appreciate the reply.

Anytime, glad to hear it's working and now everyone who reads this knows that setup can affect performance in this way. Thanks for posting the conclusion.

I'm having the same problem now. I'm trying to heat the room, and it's putting out chilled air!
Turns out that the battery on the wireless temperature sensor is dead.