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-   -   Carrier Infinity Thermostat lost power - won't power up (http://www.diychatroom.com/f17/carrier-infinity-thermostat-lost-power-wont-power-up-137468/)

The Raddish 03-18-2012 09:54 PM

Carrier Infinity Thermostat lost power - won't power up
 
I have a Carrier Infinity HVAC system, and this evening the thermostat lost power. I used my google prowess and found this, so this evening I crawled up in the attic and removed both panels. The 3 amp fuse is good, but there is an amber LED next to the fuse that is lit.

I've tried powering off the unit at both the switch in the attic and at the circuit breaker box, and powering back up. No dice.

Any ideas?

Plumber101 03-18-2012 10:08 PM

Remove the thermostat from its base.

Using a volt meter measure voltage between Terminal R and C.

Should have 24 vac

how 03-18-2012 10:11 PM

Are you saying the thermostat lost power so nothing is reading on the thermostat or are you saying you are not getting any heat?

Does your thermostat have low or dead batterys? Replace them if so.

If the batterys are good and you don't have an electrical meter, you can remove the thermostat sub base and jumper the R & W for temporary heat and to check if those thermostat wires & connections are good.
Let us know what happens

The Raddish 03-18-2012 10:24 PM

I'm saying the thermostat is completely turned off. No display, no LEDS, nothing on the screen. I'll check for voltage in a bit and report back.

I don't need heat, but tomorrow is going to be 85 and humid. So I have time.

Plumber101 03-18-2012 10:29 PM

If you don't have 24 vac across R and C then jump R to G to see if the fan come on.

If the fan comes on then you have 24vac to the stat and lost the connection between the stat and furnace on the wire connecting the C

If the fan doesn't come on then check voltage at the furnace between R and C if you have 24 vac then you lost the connection between the furnace and stat on the R connection

IF you don't get 24 vac at the furnace double check the fuse. If the fuse is ok you may have a transformer out or control board

The Raddish 03-18-2012 11:05 PM

Okay, I got the thermostat off. I have four wires:

A - green
B - yellow
C - white
D - red

My volt meter is at work (the one time I forget to bring it home).

Plumber101 03-18-2012 11:11 PM

Jumper Red and Green should turn on fan


Makes no sence though. Only four wires should have 5 for a ground

Red - 24 vac
green - fan
yellow - a/c
white - heat


Sure your stat doesn't need new batteries?

hvac benny 03-18-2012 11:12 PM

C (common) and D (hot)are where you want to check for 24 volts. Doubly check that the wires are inserted correctly into the t-stat as well as the green connector on the other end.

hvac benny 03-18-2012 11:16 PM

Quote:

Originally Posted by Plumber101 (Post 880458)
Jumper Red and Green should turn on fan


Makes no sence though. Only four wires should have 5 for a ground

Red - 24 vac
green - fan
yellow - a/c
white - heat


Sure your stat doesn't need new batteries?

The Infinity stat is Carrier's communicating stat: A and B are data, C is common and D is hot. It could be that the stat or it's screen have died, I've had a few of those.

The Raddish 03-18-2012 11:24 PM

Jumping red to any of the others does not produce any action.

Back in the attic, if I remove the fuse then no LEDS light when power is applied and the interlock held down. If I insert the fuse, I get a green LED for about a half second, then instead I get the amber LED. This tells me the fuse is not the problem.

The wires in the thermostat are tight in the jumper block.

The Raddish 03-18-2012 11:30 PM

Quote:

Originally Posted by hvac benny (Post 880463)
The Infinity stat is Carrier's communicating stat: A and B are data, C is common and D is hot. It could be that the stat or it's screen have died, I've had a few of those.

It's not just the screen. None of the LEDs are lit either, and the HVAC unit doesn't run at all.

hvac benny 03-18-2012 11:32 PM

Quote:

Originally Posted by The Raddish (Post 880468)
Jumping red to any of the others does not produce any action.

Back in the attic, if I remove the fuse then no LEDS light when power is applied and the interlock held down. If I insert the fuse, I get a green LED for about a half second, then instead I get the amber LED. This tells me the fuse is not the problem.

The wires in the thermostat are tight in the jumper block.

DO NOT jump the wires in that stat, it does not work the same way that a conventional stat does. You need to measure if you are getting 24 volts between C and D. Is it a furnace or fan coil that you have? You can try jumping R and W in the furnace, disconnecting the green bus connection.

The Raddish 03-18-2012 11:43 PM

It's a 16.8 SEER split system, that acts like a heat pump when only mild heating is needed, and uses gas when it gets cold. The compressor is a multi-stage compressor. It is four years old next month.

kilosos2 03-19-2012 11:40 AM

That really sounds like either your control board is bad. Or for sure your thermostat is out. If you have the led light on even though its amber color then you have some sort of 24 vac coming into the control board. Although it still could be the transformer isn't producing enough 24 volts to power up the control board, that is possible also. Amber led may indicate just that the unit is off. Kinda like in your computer when it goes into sleep mode. Let us know what you find. Try what hvac benny is saying to do.

The Raddish 03-19-2012 04:59 PM

Turns out the limit switch turned off the system because the top drain pan wasn't draining. Cleaned out the drains and vacuumed out the drain pan. System turned on, working just fine. :)


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