Trane ac air handler

brion182

I have a Trane air handler TWH039P 150C1 from ‘92 that just handles AC and the fan continuously runs but the compressor will cycle off. If I hit the relay I can get it to turn off so I think it’s just the relay and not the timer board. Problem is I can’t find this relay and would greatly appreciate some advice on what a replacement would be. I’ve attached photos of the original relay.
Thank you!

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pecmsg

common Relay

Supply House Dot Com

109A_5

Maybe (relay only)

https://www.supplyhouse.com/Honeywell-R8222U1006-24-V-General-Purpose-Relay-with-DPST-N-O-switching

JUGHNE

The board may be for delay on break for the fan only. Runs the fan for a few minutes after shutdown of AC call from tstat.

The board could be faulty to not shut the relay off or the relay contacts could be stuck in the on position.

IIWM, I would just go for a standard relay with out the delay.

EdTheHeaterMan

That particular combination of PC Board and relay is an obsolete part that is no longer manufactured.  You can operate it without the PCB but there is a rewire that is needed to accomplish it.  Give me a minute to consult some old posts.

EdTheHeaterMan

This is the part number of the obsolete RLY02087 relay  It is a time delay PCB that connects to a R8222 general purpose relay used to delay the start of the fan for 30 seconds while the refrigerant (evap. coil) gets cold so less warm air goes through the ductwork on start up. Then there is a 60 second delay off at the end of the cycle so additional cooling energy can be recovered at the end of the call for cooling. It was an effort to hike up the SEER rating off a Trane condenser, or heat pump, that was matched to that particular air handler.  

Since the system must be quite old and you are looking for the lowest cost repair, the overall SEER is less of a concern, so eliminating that PCB is no big deal.  The rewire is to remove the PCB completely from the R8222 general purpose relay, then remove the Red wire that powers the PCB on the one terminal of the relay coil.   If you only remove the PCB and leave the Red wire connected, the relay coil will always be powered, so the fan will run constantly.  

Typical Trane Air Handler Unit with obsolete relay wiring diagram with original on the left and the rewire on the right.

Here is what it might look like on your air handler after you remove the PCB.

HVACNUT

If the TDR is ok, then a Honeywell R8222D1014 is most common.

brion182

Thank you everyone! I will replace just the relay for now with the one that was suggested. If that doesn’t solve the issue and it’s the delay board I will re-wire using Edtheheaterman’s diagram.
After tapping the relay last night it’s been working, we’ll see when I get home from work, either way I’m going to replace the relay.

Thank you all very much!!

brion182

Ed,

I assume I can replace it then with the RLY02807? Looks like that has the time delay board built in. I think that is the way to go, looks like they’re under $100. I’ll just have to figure out the wiring.

mattmia2

I think the time delay board just plugs on to a standard honeywell/residio relay.

EdTheHeaterMan

You can use the American Standard/Trane relay with the OEM huge mark up, or you can just get the one direct from the control manufacturer. https://www.supplyhouse.com/White-Rodgers-57T01-843-Blower-Time-Delay-Relay

loamyroots11

Hey, this looks oddly familiar haha!

I originally bought the RLY02807 for around $60 online. The wiring for it is very straightforward, you can look at the manual it comes with online. However, after thinking and talking about it with the members on here, I decided against it and returned it.

For cooling, I don't want the fan to blow for an additional 1-2 minutes after the condenser shuts off. I want the fan to immediately shut off with the condenser to help with humidity. 'm in NJ and struggle with humidity issues over the summer.

So instead, I just kept the red wire that Ed highlighted disconnected and very securely capped it off. No issues since!

mattmia2

most thermostats can be set to keep the blower running a minute or 2 after the cooling call ends too if you for some reason want that feature. seems to me you just will have to re-condense the moisture you re-evaporate anyhow.

HVACNUT

https://forum.heatinghelp.com/discussion/comment/1861602#Comment_1861602

The board is usually just plugged in to the spade connectors. That one is hard wired?

EdTheHeaterMan

@HVACNUT, although the Honeywell version of that RLY2087 time delay relay with the add-on PCB is no longer available there is a White Rodgers version with the part number 57T01-843 for a lot lower price from SupplyHouse.com . You can also get he RLY02087 from SupplyHouse.com for a lot more $$$. It is the same part and does the same thing but is not a PCB attached to a general purpose relay (like the R8222). Here is the cut sheet on the WR control that shows the old and the new style as having the same part number. 57T01-843 If you look up RLY02807 on Supplyhouse.com, you can see it is more expensive, for the same exact part, purchased thru Trane/Am Std.

This is all just too much discussion for a super high efficiency air handler from 20+ years ago. You don't need the dime delay if you are trying to keep an old system operating. So you loose a quarter of an SEER point. If you are that concerned about efficiency, you would no longer own that air handler.

Just throw the TD PCB away and wire up the relay without it. Then you can get paid and move on to the next service call.

But that is a Pro view point… On your own equipment, that is a different story…. Why are you still using that old stuff? If you are waiting to save up to get a new system, finance it and put it in now ans use the savings of the new system, along with the rebates to get the lower electric bill NOW! then use the savings from the lowere electric bill to pay off the financing. Someone in your area has to be offering a financing plan with low interest.

Unless you don't use the AC that much, then keep the old gal running!