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Old 08-30-2012, 06:51 PM   #1
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AC compressor starts only when manually depress contactor


Hello,
Any expertise would be appreciated.Payne outside ac unit will start with manual engagement of contactor.
New cartridge fuses outside at service disconnect
cant detect 24v at low side contactor outside ac
can't detect 24v in furnace on the board labeled: 24vcom and y/y2 .this is the where the low side of ac outside ac unit connects outside.
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Tappan67

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Old 08-30-2012, 06:57 PM   #2
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AC compressor starts only when manually depress contactor


R is your 24 volts at the board. The board does not send power to the y terminal until the stat is on call for cool. Then it's y and com.

Is there a drain pan under the unit? Does it have a switch attached to the side? Is there water in the pan? If there is water in the pan then lift the switch from out of the water so the float device lowers while on call for cool.

Let us know.

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Old 08-30-2012, 07:02 PM   #3
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AC compressor starts only when manually depress contactor


first check for 24 volts from the R terminal on the board, to C or to the actual cabinet. make sure that if there is a door switch on the furnace that it is pushed in to allow power to the board, while the doors are removed. once it's confirmed there is or is not 24 volts at the control board we can assist you better.

Even easier than that, will the fan only come on from the thermostat? Heat? If so then you have 24 volts at the board.
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Old 08-30-2012, 07:03 PM   #4
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AC compressor starts only when manually depress contactor


Hi Doc,
I cant get to the sheet metal screws that open up where I think you asked. There appears to be a drain pipe that makes acces to the those screws difficult.
I'll get it open and get back.
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Old 08-30-2012, 07:04 PM   #5
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AC compressor starts only when manually depress contactor


I meant under, not inside, the entire unit. What I'm talking about would be a secondary drain pan. What type of unit is this, electric air handler or gas furnace? Is this horizontal or vertical, closet or attic or basement? Can you take a pic?
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Old 08-30-2012, 07:23 PM   #6
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AC compressor starts only when manually depress contactor


Need a flexible socket extender there is schedule 40 pipe blocking access. Once I have one I will reply.
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Old 08-30-2012, 07:29 PM   #7
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AC compressor starts only when manually depress contactor


shut the disconnect off outside on the condenser...remove the stat off the subbase jump R to Y on the stat...contactor on condenser should be in....if not jump R to Y on board no againn...check for 24Vs at the pair of low voltage wires out of the brown wrapped bell wire......remove terminals off contactor coil ring out should be a resistance or shorted...if no ction on the metr set in OHMs the coil in the contactor is open need a new one..
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Old 08-31-2012, 11:33 AM   #8
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AC compressor starts only when manually depress contactor


Ill try to attach a photo.
Its a vertical gas furnace in garage.
Model carrier weathermaker 8000 ts
The furnace side functions like normal its the just the ac that wont start
when therm calls for cooling.
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AC compressor starts only when manually depress contactor-furnace.jpg  
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Old 09-04-2012, 04:47 PM   #9
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AC compressor starts only when manually depress contactor


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shut the disconnect off outside on the condenser...remove the stat off the subbase jump R to Y on the stat...contactor on condenser should be in....if not jump R to Y on board no againn...check for 24Vs at the pair of low voltage wires out of the brown wrapped bell wire......remove terminals off contactor coil ring out should be a resistance or shorted...if no ction on the metr set in OHMs the coil in the contactor is open need a new one..
Making progress finally. Jumped at stat nothing happened. Jumped at furnace r to y and I could hear the contactor click on and off. Powered up at service connect and now ac is running fine. My problem seems to be between furnace board and thermostat. What should I try next.

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Old 09-04-2012, 05:55 PM   #10
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AC compressor starts only when manually depress contactor


biggles,
I just double checked and reattached wires at stat and it did not make the ac compressor turn on. Do you think I should buy a new thermostat? Any help is very appreciated. Thanks
Steve
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Old 09-04-2012, 06:46 PM   #11
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AC compressor starts only when manually depress contactor


If you jumpered it at the stat and nothing happened it's most likely a wiring issue. Don't buy a thermostat yet. Any way to check out the wiring?
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Old 09-05-2012, 12:09 PM   #12
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AC compressor starts only when manually depress contactor


I took each wire off stat checked for wear andreattatched. Still wouldn't starts AC. Not sure what next step should be.
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Old 09-05-2012, 02:17 PM   #13
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AC compressor starts only when manually depress contactor


cable from stat to furnace

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Old 09-05-2012, 07:34 PM   #14
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AC compressor starts only when manually depress contactor


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Originally Posted by tappan67 View Post
I took each wire off stat checked for wear andreattatched. Still wouldn't starts AC. Not sure what next step should be.
Run a new wire from the stat to the furnace. Is that possible for you to do?
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Old 09-15-2012, 01:32 PM   #15
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AC compressor starts only when manually depress contactor


I was in the process of making a short wire to hook up my old stat to board in furnace so i could stand right there and not have to pull wire to see if it would work and noticed a wire that had come off board. I stripped and reattched and put stat back on wall and it worked!!

Thanks to all for your expertise.

Steve

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