The title says it all. I'm trying to troubleshoot a strange issue.

We sold a home in a different part of the state last year and purchased another home farther South the first part of this year. The home is a 60's Atomic Ranch that originally had no A/C. It was added at a later date and is currently a 1999 Trane over/under package unit. Most of the older homes in this area are set up this way.

The unit works very well and is actually a little too much for the house. When we bought the house I basically disassembled the entire unit, removed all the old insulation and re-insulated the entire unit inside. The unit is in overall "good condition" and worked flawlessly before re-insulating. Previous repairs to the unit are unknown.

About one week after re-insulating the cabinet, the evaporator fan would randomly not want to come on. Then, occasionally the evaporator fan would cut off while the compressor was still running. Learning that all Trane's of this vintage came with a factory hard start kit, I found that tapping on the hard start relay would cause the fan to come back to life. This made no sense to me, because I thought the hard start kits were designed to help compressor starting only? Anyway....

After putting up with several weeks of this I finally called a local A/C tech out. He put his tester on the fan and ruled that out. So, the fan is good (not drawing too many amps while running or at start up), the fan start capacitor is good (but not replaced by me). While he was in there fiddling around, he found that tapping on the other relay (timer relay?), the evaporator fan came to life! So he replaced that relay and $150 later I was good to go. This was all about 1 month ago.

Now, about 1 week ago the same issues with the evaporator fan cutting out while the compressor is running have started happening again. This time there is lots of "clicking" going on out at the unit and all of the clicking is coming from the new relay that was installed. If I go out there and tap on that relay, the fan will come to life again. So, for the past 5 days when the fan has not been working, I go out and tap on the relay to get the fan going.

OK.... Here is where it gets interesting! So, I have had the access panel for that relay removed, so I can "tap the relay" when I need to. Yesterday we had some hard rain and I forgot to put that panel back on. In a panic, I ran out there, Turned off the breaker and re-installed the access panel (in the pouring down rain). After turning the breaker back on, the unit has run flawlessly ever since! Not one hiccup and the fan and relay are both working fine.

So, is it possible that I have a weak or bad circuit breaker that feeds power to the unit? I would think that if the power were low or erratic that the compressor would not run, since it obviously draws more power than the evaporator fan?

Puzzled.... Sorry for the long winded post. Difficult to describe.

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AJ

1985 300D (SOLD)

Does it throw up a code? Not sure but that's the first thing I check when mine doesn't work.

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You don't need a weatherman to know which way the wind blows - Robert A. Zimmerman

I would check the contactors. I've been nursing a 40 year old gas pack along for years, replacing parts as they go bad. My unit has two contactors for the fan and compressor. They are open frame so you can literally see them energize.

When one of them failed, I could take a screwdriver (CAREFULLY! 240V!) and press the center of the contactor and the fan would start up.

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-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

Thanks for the input! I just realized that I should have put a list of stuff thats been replaced to my knowledge up there. New stuff:

1. Hard start kit (relay and capacitor). I installed.
2. Run capacitor. Previous owner installed.
3. Contactor. Previous owner installed.
4. Timer relay. Recent A/C tech installed.

It is interesting that you mention the contactor. I only see one in my unit (Trane XE1200). I found the old one in the garage (previous owner). The one that is in there now looks literally brand new and I have taken the cover off and manually energized it. Everything worked fine. I guess it is possible that a new faulty contactor was installed?

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AJ

1985 300D (SOLD)

OK, so when you manually energize the contactor, the unit works properly?

If so, I would pull and re-seat all of the low voltage connections relating to the contactor, the coil, low voltage cutoff switch (if equipped).

It sounds to me like poor voltage to the contactor.

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-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

Breakers go bad all of the time. They are cheap and easy to eliminate as a possible problem.

Yes. The contactor is working correctly. Or at least it appears to work correctly. The unit starts up and runs fine, cools great, etc... Problem is that after a minute or 2 of running that big timer relay starts clicking on and off. When it does, the fan speed goes up and down and sometimes it shuts off completely. Then more clicking and after a minute or 2 the fan comes back on. Meanwhile the compressor and Condenser fan continue to run unabated.

During periods when the unit is running and the evaporator fan shuts off, I can actually go out there and tap on that big relay and the evaporator fan will kick back on.

Yesterday, I went out there to tap on that timer relay and I decided to check the circuit breaker again. Just touching the circuit breaker caused it to fall and shut off. So, obviously the circuit breaker is bad. This is an old house and the circuit breaker looks like it has been through the ringer. I'm going to replace that here late today or tomorrow.

More weirdness though. Before I left the house this morning, I turned the unit off so it would not run while I was gone. I just got home about 1 hour ago. So, I went out there and firmly flipped that circuit breaker, came back inside and turned on the unit and no issues at all! It has come on about 4 times now and it is working perfectly. The relay is not clicking, the fan is not shutting off etc...

Agreed!

It must be related to voltage or some sort of timer malfunction right?

I'll know more after I replace the breaker. Thanks again for all the input!

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AJ

1985 300D (SOLD)

In my house, I had to replace the entire breaker box because at the time, it was 30 years old. I was getting arcing in the lights and heavy loads. When you pull the breaker, check the buss bars and make sure they're clean. You may have a high resistance connection there that's contributing to the problem.

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-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

I never did get around to fixing the circuit breaker because I had to leave town for a few days last week. I still plan to replace it the next few days. It is definitely weak. That was not the problem though.

I finally broke down and pulled all the electronic components out of the little hole in the side of the unit. When I did, the problem was obvious. The little printed circuit board attached to the "time delay relay" had several broken solder joints. So, I removed the circuit board from the relay, repaired the broken solder joints and it is working like a champ now!! I found the part online. The circuit board comes with a new relay. They are packaged together. $31 shipped. Will be here later in the week.

Glad I found it! Intermittent stuff is such a PITA to figure out and fix!

Thanks again for all the help above!

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AJ

1985 300D (SOLD)

Imagine trying to find an intermittent ground fault in a 20,000 square foot buildings fire alarm! Those days suck!


If that breaker is infact getting sloppy, replacing it would be good for the unit. Might even lower the power bill a little bit. Mine dropped like a rock when I replaced the 60 year old load center. ( breaker panel)

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have no worries.....President Obama swears "If you like your gun, you can keep it

I did it on aircraft for many years. BUT, that was many years ago!

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AJ

1985 300D (SOLD)