Trane XL 1200 heat pump fan stays on

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Old 04-24-13, 06:24 PM
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Trane XL 1200 heat pump fan stays on

I have a Trane XL 1200 heat pump (outdoor unit: TWX042, indoor unit: TWV064). Recently, the fan does not cut off even when I set the thermostat system to "off," and fan to "auto" (it only has "auto" and "on" setting). And I had to go to the breaker to cut it off. But sometimes it cut off on its own (well, since the weather turned cold again, I cannot leave it off). I have had this unit for many years, and I can tell you this is not normal behavior. (Usually, the fan may stay on for a little while to clear residual warm air off the duct, but it won’t last for a couple of minutes).

I suspect somewhere contact could be stuck. But where? Where should I look? Outdoor unit? Indoor unit? Thermostat? Any help is appreciated.

BTW, I have a simple ohm/voltage meter.
 
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Old 04-24-13, 06:49 PM
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Welcome to the forums.

I can only help you if I can find the model number. I don't see any service info listed under that model number. The pro's will probably recognize that partial model number.

Does your air handler use electric heat strips or a fossil fuel for heat ?
If you have a heat strip then an educated guess would be a problem with a heating coil sequencer.
 
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Old 04-24-13, 07:10 PM
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I would consider this a sequencer problem until proven otherwise.
High voltage is present when checking a sequencer



 
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Old 04-24-13, 07:24 PM
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Trane does not use sequencers..... It is likely the fan time delay relay. Again, need full model number of indoor unit to help further.
 
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Old 04-24-13, 08:27 PM
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The full model number of the indoor air handler is TWV064E150C (variable speed), with electric heat strip (Trane BAY96X1514) and Trane Weathertron mechanical thermostat.

Thank you for your help!
 
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Old 04-25-13, 07:15 AM
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That is not a valid model number for the air handler. How about a serial number?
 
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Old 04-25-13, 04:46 PM
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That is the model number I copied from the Installer's Guide (see attaached). In fact, as I pulled off the cover and wrote down the serial number, the model number was lsited on the unit right next to serial number as "TWV064E150C1" (with one additional digit "1" at the end).

I copied down the serial number: G12327118.

Again, thanks in davance.
 
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Old 04-25-13, 04:55 PM
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The serial number did not come up but the full model number you gave did....

You do NOT have a variable speed blower... it is multi speed which is a huge difference. Here is what you need:

Part Item Number RLY02807
Description RELAY; TIME DELAY, POWER POLE-7 FLA, 36 RLA AT 240VAC, PILOT POLE-25 VA AT 24 VAC, 2 SEC ON-DELAY (INCLUDES PC BOARD)

This is a superseded part from the original and is wired slightly different as it is not the same exact part as the original.... Take a picture of wiring and denote the terminal designations before removing the old relay and circuit board assembly.
 
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Old 04-25-13, 05:37 PM
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Don't know, the whole document referred it as "variable speed" (so much for truth in advertisement).

You are right, I cannot find that part number in the parts list in my docuement. Do you have a picture of where it should be?

I am also not confident that I can transfer the wires correctly, since the new is not the same as the old. Winder if it is time to call in a professional.

I did find a picture of the unit off the net.
 
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Old 04-25-13, 05:49 PM
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The original part number is RLY01221 and looked like this...



It looks like this original part can still be bought online and is Honeywell part number ST82D1004/U
 
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Old 04-25-13, 05:57 PM
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It says it has that part, can you look and verify if it is in your AHU? Your AHU is very old and it has the ECM 1.0 motor and control and so it should have that FDR. And it is still very likely the problem.

And.... MY MISTAKE..... you DO have a variable speed blower
 
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Old 04-25-13, 06:16 PM
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I do have a RLY1221 (missing leading 0 though) on my parts list. Guess they are the same?

So if I buy the Honeywell part, it should fit exactly?
 
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Old 04-25-13, 06:18 PM
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Yes it should fit exactly.
 
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Old 04-26-13, 06:54 AM
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I think I am about to throw in the towel. Without in-depth knowledge to go on, I was trying to find the unit by its look, but just cannot find it.

Many thinks nevertheless.
 
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Old 04-26-13, 07:47 AM
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I will get you a picture of where it should be located in the controls section of the ahu.... typically those were on either side of the ahu behind the the blower door with a sheet metal door in front of the controls.
 
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Old 04-26-13, 05:33 PM
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I took down the sheet metal door and this is what I saw:
 
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Old 04-26-13, 05:36 PM
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That is the heat strip contractors above the blower. If your ahu is horizontal flow then the box you are looking for is on the top or bottom of the ahu.
 
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Old 04-26-13, 06:28 PM
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Mine is vertical air flow (from bottom to top), and it looks like this:
 
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Old 04-27-13, 07:12 AM
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Item # 608 located in the box that the low voltage terminal board is mounted on

 
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Old 04-28-13, 03:36 PM
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Sorry for being so think. I drew an arrow in my picture, is that the box you were talking about?
 
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Old 04-28-13, 03:51 PM
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No.... to the right...... the lvtb is brown and has wires going to it and looks just like my picture... you probably need to call a professional...
 
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Old 12-24-13, 01:46 PM
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Finally had a professional installed it for me (It was an intermittent problem, I waited till it becomes consistent to call in professional help, so they can diagnose the problem when it happens). As it turned out, hvactechfw’s diagnosis was absolutely correct. The fan is supposed to have a 80 seconds delay when the system turns off (to use the remaining hot or cold air). But with a bad rely, it just stays on and never turns off.

hvactechfw was also correct that Honeywell ST82D1004 should fit perfectly. My old unit actually has Honeywell part number ST82M1004 stamped on it. Trane now uses RLY 02807 (see the picture I posted in #9) to replaces it, which is what the contractor installed for me.

Well, if I had known where to look (it is in the box below my arrow in #20, you need to open it to see it), it would have saved me $165 labor cost the contractor charged me. But he needs to come back the second time (because he didn’t have the part), and took a long time to fix it, so I guess it may not be all that easy to get to it. (I was charged $48 for the part, which is fair I think.)

Thanks hvactechfw for all the helps, I hope posting my experience here may help someone else.
 
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