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Second stage compressor will not start

Last Post 18 Dec 2009 12:49 PM by jml. 3 Replies.

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elariviere User is Offline

New Member

Posts:5

16 Dec 2009 11:28 AM
I have a heat Controller Inc GeoMax 2 3 Ton heat pump that won't turn on the second stage of the compressor. The heat pump does not have electric backup heat yet. I have a Hunter touchscreen programmable thermostat model 44860. The interface board of the heat pump is as follows: Y2 Y1 G O W NC CI R DH AL1 A I have it connected to the thermostat as follows \| \| \| \| \| \| \| Y2 Y1 G O C RC/R L The thermostat also has W2(aux), E(Emergency), B(Reversing valve Heat), And W1(Heat stage 1 which they say is for conventional HVAC). Stage one works fine. I have also switched from heat to cool and that Also worked. Does anyone have any Ideas. Thanks,

geo fan

Basic Member

Posts:408

16 Dec 2009 07:53 PM
ok if you have a voltmeter you need to check at the unit if you have 24v across Y2 and C if so forget the wires and stat cuz there fine I would also check the back programing of the stat to make sure set up for a 3 heat 2 cool heatpump

elariviere User is Offline

New Member

Posts:5

18 Dec 2009 08:35 AM
I have placed a jumper across Y1-Y2 at the thermostat. It forces the second stage to come on with the first. So I know that it works. I'm not sure what you mean by back programing. I can't find where to change the stages on the thermostat. Thanks,

jml

New Member

Posts:55

18 Dec 2009 12:49 PM
So that tells us that second stage on the heat pump works OK as long as a 24v signal is getting sent to Y2. But it sounds like Y2 on your thermostat isn't providing the required 24v output when 2nd stage heating is called for. To verify this, take your jumper off and follow geo fan's suggestion to use a voltmeter to check the voltage between Y2 and C when the thermostat is calling for stage 2 heat (crank the heat to get this to kick in). If there's no voltage check your wiring connections, and try testing the voltage between Y2 and C right on the thermostat's wiring terminals. If you get zero volts here when the thermostat calls for stage 2, you'll likely need to replace the thermostat. The thermostat manual is here: http://www.hunterair.com/ssi/pdf/hunter/44860-Owners-Manual.pdf or here: http://www.hunterfan.com/uploadedFiles/Support/Downloads/44002(2).pdf?n=7262 System settings adjustments for this thermostat are on pages 27-29, but there doesn't seem to be any way to configure the number of stages, just when the stages will kick in. I see that this thermostat is listed as only being able to control up to 2 stages of heating, but the back page of the manual includes a wiring diagram for a 2 stage heat pump with aux/emerg backup heat. I'm not entirely sure whether you would need to replace it with a 3H/2C model if you plan on adding electric back-up coils.