Aux heat wont come on

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Old 11-29-10, 08:10 PM
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Aux heat wont come on

I have a carrier hp with a carrier gas furnace as aux. Attached to the furnace is the carrier "Optimizer II", where i think i may have a bad relay. The gas furnace is not turning on when the thermostat calls for aux heat. Tried putting thermostat on emergency and still nothing.

I jumped out the red and white on the furnace when the blower is running and can get gas heat that way, Im thinking it could be the furnace lockout relay but not 100 percent.

any help is greatly appreciated
Ben
 
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Old 11-29-10, 09:08 PM
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Could be a bad relay, I'd take a meter and check to make sure that you are getting power to W or E? (Don't know whats on the duel fuel kit since we don't have a model #), on the stat side, and then check to equipment side too.

If a new board is needed, maybe retire it and upgrade to a new HOneywelll stat that will take care of this.
 
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Old 11-30-10, 09:15 AM
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Carrier HP. 38YH018300. Thermostat. White rodgers digital comfort set II 1F92-71. Carrier. Furnace 58GP050-BA. Series 100. Everything is original from 1986.
 
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Old 11-30-10, 08:21 PM
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What's the model # on the duel fuel control?
 
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Old 12-01-10, 07:10 AM
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What's the duel fuel control?
 
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Old 12-01-10, 07:35 AM
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Sorry I should have looked up a dual fuel controller berofe posting. I will check the model number, if there is one. On my system it is a seperate box attached to the side of the gas furnace. It is not a typical printed circuit board with relays built in. Mine has power coming in to a transformer with four different relays screwed to the enclosure. It is called the optimizer II by carrier. I will check number when I get home
 
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Old 12-01-10, 05:56 PM
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the model number on the cover of the duel fuel control box is 306174-301.
 

Last edited by Jammin'; 12-01-10 at 07:15 PM.
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Old 12-01-10, 07:12 PM
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optimizer II



hope this helps to explain my duel fuel control box
 
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Old 12-01-10, 09:12 PM
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Wish I had time right now, but I don't. Just got home from work, and I have to back first thing in the morning. I'll try to get abck to you soon as I can.
 
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Old 12-02-10, 07:28 PM
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Ok, I did a bunch of digging, and not able to find anything on this...

What letters are on there say "Heat Pump" "stat" and "furnace" side?
 
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Old 12-03-10, 01:46 AM
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R-- looks to be 24v coming in
O HP
W2 HP
Y HP
O Thermo
G Thermo
W2 Thermo
Y Thermo
C-- Common
G Furnace
R furnace
W furnace

hope this helps
 
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Old 12-03-10, 05:19 AM
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Ok, Take a meter and read between W-furnace, and C-furnace, and you should be reading 24 volts when the stat is calling for gas heat. If you are getting a reading, then trace the wire to make sure the relay is getting 24 volts. If it is, then the relay needs to be replaced.

If you are NOT getting 24 volts, then you will have to take the t-stat off the sub base, and jumper R and W there.
 
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Old 12-04-10, 02:59 AM
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so i took a reading from furnace W to C and didnt get any voltage when aux heat is called for. I removed the sub base and got 26.6v from R to Wt2 on the dual fuel control.

should i have put a jumper between R aand Wt2 and then check my furnace readings? im confused
 
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Old 12-04-10, 05:40 AM
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No, take a reading at the duel fuel control W and C that goes to the furnace.
 
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Old 12-04-10, 02:01 PM
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I dont have a C-Furnace, the Furnace only has R G and W. The C on the duel fuel control is only for the heat pump and stat. The reading from C to W-furnace is 0 when aux heat is called for.

The reading on the duel fuel control (R to W2-thermo) when the sub base on stat is removed is 26.6v
 
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Old 12-04-10, 09:27 PM
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Don't read R and W2, you are going to get a voltage reading from R.

Read W to ground.
 
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Old 12-05-10, 06:15 AM
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Not sure which W you were asking for. When Aux heat is called for W-Furnace to ground reads 0v, W-stat to ground reads 26v
 
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Old 12-05-10, 07:03 AM
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What letter on the control is tied to the furnace's W? Take a reading on that to ground.
 
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Old 12-05-10, 07:14 AM
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On the control, W-furnace to ground reads 0 voltage when aux is called for
 
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Old 12-05-10, 07:18 AM
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See if you can trace the wire from the t-stat Aux heat to the relay. if the relay coil is reading 24 volts, then the relay needs to be replaced.
 
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Old 12-05-10, 07:31 AM
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not sure if this pic of the schematic will be readable or help you out.

thanks jay i really appreciate your help
 
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Old 12-05-10, 08:01 AM
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What reading are you getting between 5 and 6, and 2 and 4?
 
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Old 12-05-10, 08:25 AM
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Between 5 and 6 i am getting 27v. Between 2 and 4 i am getting 26v. Is there a good place that sells relays online?
 
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Old 12-05-10, 09:17 AM
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Ok... Should be reading 0v between on of them. not both.. Are you reading voltage on the coil side of the IR?
 
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Old 12-05-10, 10:01 AM
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No I am not getting voltage on the coil side of the relay (just to make sure, you mean between 1 and 3 on the relay, right?)
 

Last edited by Jammin'; 12-05-10 at 10:31 AM.
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Old 12-05-10, 05:05 PM
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If you are not getting voltage in 3 and 1, trace back to IR 4 and 6. if that is open/24 volts, then take a reading on IR C and C coil
 
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Old 12-05-10, 06:58 PM
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So i dont have voltage across the relay(1 and 3). i took a reading at the interlock relay across 4 and 6 and i still did not get any voltage.

all of the readings were still taken when the stat is calling for aux heat.
 
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Old 12-05-10, 07:36 PM
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You are not going to get a reading on the "same side" of the line. if you took a reading from one of those to ground, then you'd get a reading.
 
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Old 12-06-10, 02:16 PM
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Ok, so i have 24v at both sides of the coil on the Furnace Lockout Relay (1 to ground and 3 to ground).
 
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Old 12-06-10, 07:49 PM
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Huh!? How can you get a reading on 1? The load "burns" up the power, so it should be reading 0.
 
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Old 12-07-10, 04:14 PM
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Nope, i was getting 24v at 1 and 3. This was the same relay that i got voltage at the N/O and N/C contact at the same time. Picked up a new relay today and so far everything seems to be running as normal.

Thanks for the help jay

Not sure if i should start a new thread, but i was wondering if all heat pumps have a temp. setting that can be set when to switch to aux. heat. The HP is a Carrier model # 38YH018300
 

Last edited by Jammin'; 12-07-10 at 04:49 PM.
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Old 12-07-10, 09:03 PM
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Glad the new relay is working out for ya.

What is the rate for your gas, and electric?
 
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