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Discussion Starter #1
Occasionally, perhaps once or twice a year, my reversing valve would get stuck. It would usually correct itself if I switched between heat and cool a few times.

Earlier this week, my house was cooling as usual.

Then smell came out vents, then AC cut off. Nothing tripped. Thermostat lost power. Transformer in the air handler burned up, hence the smell.

So I got a new transformer and some fuses and began looking for a short.

Tracked it down to orange wire. Left orange wire disconnected.

Thermostat is on. But now whether i cool or heat, it is stuck in heat. The reverse valve seems stuck.

And I think the orange wire, disconnected, it was powers the reverse valve or else tells it to shift.

So how do I further diagnose what is causing the orange wire to short?

I'm thinking it is either the defrost board, wiring to the reversing valve, or the valve solenoid. Which do you think is more likely to short? Or is it more likely that wiring going to the valve solenoid is chaffed somewhere and shorting to the condenser sidewall? I'll have to follow the orange wire along. But I'm also curious if a part was failing, eventually failed, and therefore causes a short?

Any way to force my switch valve to switch so I can at least get it to cool while leaving the orange wire disconnected temporarily until I track down the short?

If anyone wants some tips on how I tracked down the short in the low voltage, or how I replaced the transformer, I'm willing to share some diagnostic tips or pictures to be helpful to someone else. Let me know.
 

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Any way to force my switch valve to switch so I can at least get it to cool while leaving the orange wire disconnected temporarily until I track down the short?

There is a tool you can buy, if your near an HVAC supply store like Grainger, they might sell you one.


https://www.grainger.com/search?searchBar=true&searchQuery=solenoid+valve+magnet



I've used a strong magnet to open a water solenoid valve, don't know if that would work on a reversing valve. Chances are your sticking valve will take out a new coil eventually.
 

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Discussion Starter #4
Thanks for the help.

Is it possible that this failed part would also be the cause of the short?

Whenever I reconnect the orange wires, it immediately burns out the fuse. Even when the thermostat is set to OFF.
 

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Yes, the valve armature is stuck and that causes the operator coil to draw several times its normal current. That's what made it fry and short.

If you only replace the coil, it will likely burn out right away unless you are one of the lucky few that has things get well on their own. Not many of those around. :wink2:

You'll have to replace the valve to put an end to it. Get an estimate and see if you might want to consider some other path. Probably cost you in excess of $600 to hire it done.
 

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Discussion Starter #6
Thank you surferdude2. Although, you have me worried about a $600 price tag. I live in South Carolina. All i really care about is cooling.

What if I could just get it unstuck, and then be stuck with cooling? Could I use a magnet to try to manually pull the valve (armature?) out and get cooling while I save up for a new and more efficient condenser and have it replaced during winter time when HVAC techs have more free time and charge less? Am I wrong to assume that the valve is only activated when I switch between heating and cooling?

So now I am going to disconnect the plug at the valve solenoid coil and see if it stops shorting. That way I can be for sure that I've located the component causing the short. I will report back.

I can post pictures if anyone is interested in taking a look at how I'm diagnosing this.
 

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Thank you surferdude2. Although, you have me worried about a $600 price tag. I live in South Carolina. All i really care about is cooling.

What if I could just get it unstuck, and then be stuck with cooling? Could I use a magnet to try to manually pull the valve (armature?) out and get cooling while I save up for a new and more efficient condenser and have it replaced during winter time when HVAC techs have more free time and charge less? Am I wrong to assume that the valve is only activated when I switch between heating and cooling? If you can use the magnet trick and possibly tap on the valve body to get it going, it might stay in that mode so long as you don't remove the magnet. There's no guarantee since it's pilot operated and it's likely to return to its native/favorite stage when you shut the system off, which ain't cool. May be worth a shot anyway for the short term if nothing else.

So now I am going to disconnect the plug at the valve solenoid coil and see if it stops shorting. That way I can be for sure that I've located the component causing the short. I will report back. That's the last step of the test to be sure of what has failed.

I can post pictures if anyone is interested in taking a look at how I'm diagnosing this.
Go for it. With the SoCal climate, if you get it going on cool, that's cool!
 

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Am I wrong to assume that the valve is only activated when I switch between heating and cooling?

So now I am going to disconnect the plug at the valve solenoid coil and see if it stops shorting. That way I can be for sure that I've located the component causing the short. I will report back.

The coil is energized for cooling and defrost modes. Another option for you if your test shows the coil is the culprit is to just replace the coil. Put the system in cooling mode and cycle the reversing valve 10-15 times, might dislodge a speck of something that's possibly jamming the valve. Replacement coils aren't very expensive, i think it's worth a try.



https://www.supplyhouse.com/sh/control/search/~SEARCH_STRING=reversing valve coil?searchText=reversing+valve+coil
 

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I agree.. the coil is probably cheaper than the magnet anyway. It won't fry immediately so it'll last a long time for testing and maybe even long term operating.

Depends on blind luck. :plain:
 

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Discussion Starter #10
Hey guys, I removed the coil. It is really a small part that fits inside the palm of my hand. Had two prongs.

After unplugging it, the orange wires stopped shorting. So now I have everything wired back the way it used to be, with 3A fuses on the low side of the transformer.

I realize that this part can be purchased for less than $30. I am going to try to replace the coil, and probably order the magnet too.

HVAC parts suppliers, including a local Grainger and another place that specializes in HVAC parts, is closed for the weekend. No wonder AC techs charge more on weekends. Getting parts is difficult.

So I am going to stay near a window unit until Monday.

You guys have been a huge help in diagnosing this.

I am hoping that some water I saw on the capacitor (it was raining all week) caused a temporary arc, that took out the solenoid coil, but the reverse valve is still in tact and not actually stuck, it's just not energized. I'll cross my fingers. That would mean that the repair cost me less than $50 total (transformer, fuses, solenoid coil).
 

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Discussion Starter #11
I tried testing the solenoid coil on the bench with multimeter measuring it for ohms. It read 0.6 ohms, which seems really low. I read online that normal solenoid resistance should be 10-60 ohms.*

Whatever it reads in ohms, I know it was the root cause of my short.
 

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I had to check out of curiousity just to see if the valve would stay in cool mode if you managed to use the magnet to get it going. Looks like it would stay they through thick and thin and shut downs and all.

The magnetic coil pulls a sliding valve gate against a spring. Holding it there with a magnet will keep it in cool mode until the cows come home.

Check out the this link that seems to verify that.

How a Reversing valve works
 

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From the article Surferdude posted:



"99% of the reversing valve failures are due to bad or faulty electrical coil and not because the valve itself has failed. So the next time an air conditioning service man tells you that you need to change the reversing valve, chances are he doesn't know what he is talking about or he want to rip you off."


I don't work on many heat pumps here in the high Rockies but I would rather change a coil than the valve itself. I'm really lazy too.:smile:Hope the coil replacement fixes everything.


 

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We can hope.

I hope that's the case but the OP has had a long time problem with the valve not switching to cool without several on/off pushes on it. If the coil does the trick, he may want to get a lottery ticket and see if that string of luck will hold up. :smile:

Hopefully he'll post back one way or the other so I/we can raise a cold stubby Coors (first produced the year I was born) or equal and toast his good fortune. Even if it doesn't work, we can toast that too. :devil3:
 

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Discussion Starter #17
A bit off topic but dollar general sells 15 packs of keystone light, which is a poor man's coors, and produced by coors company. And it's actually not too bad. Not as goods as the Coors Banquets you reference. I usually start off with a couple good craft beers or other premium beers and then move on to cheaper beer when I'm a bit too tipsy to notice the difference in quality anymore. I've learned from experience which cheap beers leave me next morning swearing to never drink again, and which ones I recover from easy with just a cup of coffee.

If you ever want to lose weight, try going a month without a beer. I know it sounds like torture, especially during summer time, but cutting the carbs out is a quick way for me to slim down when I need to crawl through a crawl space or attic to fix an AC leak or just check that termites haven't moved into my crawl space.
 

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Discussion Starter #18
Great News!

I finally got the new solenoid coil and the backup option - the magnet, in the mail yesterday.

I had to order the parts online because no place locally even sold solenoid coils for HVAC's. Not even an HVAC parts supplier! Grainger neither. Wow.

I ordered the parts from SupplyHouse.com Great bargain! Shipping was only $5 and items arrived 3 days from time i placed order. I think the parts shipped out of Ohio. Customer service was great. $17.50 for the solenoid coil, $25 for the magnet.

I installed the solenoid coil first. Turned the breakers back on, turned AC on, and COLD AIR!!! YES!!!!

I am sitting under a cold AC vent as I type this. Whew. So I went over a week without AC in the middle of July. Looking at my digital AC log, it got as high as 91 degrees INSIDE my house on the hottest day, even with a window unit on full blast the whole time. yikes! Unplugging a bunch of electronics upstairs helped stop some of the interior heat. (phone chargers, tvs, surge protectors, amazon fire stick, TV antenna, etc.)

I owe a huge amount of gratitude to both surferdude2 and 57TinkerMan who were both very knowledgeable and extremely helpful.

I hope this thread serves as assistance to others who experience shorts, tripping breakers, and low voltage problems. When I get a chance, I'll try to upload some of the photos I took throughout the process.

All in all, I spend $35 on transformers, $12 for a pop button 3A fuse, $5 on a box of 3A fuses, $45 on a coil and magnet, and wiring i already had and a multimeter i already had. I could have cut the transformers cost in half if I took extra precaution with fuses the first time to not burn the first one out. For less than a $100 I learn a lot about how My home HVAC works, i have extra fuses in there, an extra magnet as backup if the coil ever dies again, and the satisfaction of fixing something myself instead of calling HVAC techs who I believe would have NOT had the patience to track down a short and would have attempted to just sell me a new condenser given the age of mine.
 

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That's good news for sure given how hot the weather is going to be for a while. It's great when a plan comes together, especially the part about the cold Coors stubby salute you'll be getting now!

Now consider this... if you still have problems getting the valve to function occasionally, like you did before, that will fry out this new coil in time. In that case it would be smart to use the magnet all summer to prevent that. Just unplug the coil and lay it aside to keep it from being tramatized and cooked occasionally. The magnet can stay on there until the frost hits the pumpkins!

All the best, SD2
 

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Discussion Starter #20
I still believe that rainfall for several days straight caused water to get inside the electrical control box attached to the corner side of the outdoor condenser.

The transformer burned up while it was raining outside. Water was puddled up around the capacitor contact points that evening when I began diagnosis.

The puddled water on top of the capacitor likely caused it to temporarily arc. This hypothesis could be false if the capacitor assists voltage on the high side and doesn't effect the low voltage side. I'm not sure.

I think that I need to seal up that box better for peace of mind. I have some double sided insulation tape. Maybe I just duct tape all around it too and strap that capacitor into a dryer, tighter place.. Whatever it takes to keep water out of the compartment.
 
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