Regular Guest
Good day. This is my first post here. I have been in the hvac/r field for about 6 years now. I have came across something that I have never incountered before. Here is the run down.
My brother-inlaws ac unit is an older coleman single stage electric/gas package unit. He had a new heat exchanger put in last year. Ran great during the winter months. Switched to cooling mode and got nothing. I showed up with meters in hand. I didnt have control voltage. Replaced the transformer. The control voltage is now back. I can get the indoor fan to run, the gaspack will run, but when you switch to cooling, you get nothing, but a blown transformer. Replaced the transformer, and put an inline fuse in to protect it. I can get the compressor to run by manually pushing in the contacts.
I put my meter on the red wire and the yellow and had continuity. Jumping the gun, I pulled a new wire thinking there was a dead short in the jacket. After new t-stat wire pulled, still have continuity between the two wires. Now, If I pull the moulex plug of the control board, I lose the continuity between the red and yellow wires. Also, if I remove any wire off of the contactor, I will lose the continuity also. I have replaced the contactors, the start/run caps. I have pulled the whole harness out, there is no chared or broken/skinned wires. My brother inlaw is limted on money. I pulled the boared, and checked it over. The board looks good, and works for everything, but the cooling. We also put on a new t-stat. Before I order a board, would anyone here know what might be my "gremlin".
Like I have typed above, I have never hit a bump like this. The only thing left in the cooling circuit that hasnt been renewed is the board. Any help would be greatly appreciated.
Thanks,
Brad
Professional Member
wow......
you've tried looking for the dead short? And couldn't find it.
So why did you replace the caps? they are not control circuit. You need to go back to the basics. Rule everything else out by testing it, not just throwing a new one in. You could be replacing a bad part with another bad part. Ever think of that?
I fully support the military and the War on Terrorism.
If you don't know, then don't do. If you don't know and still do, then be prepared to pay someone else a lot to undo what you did and then do it right.
If you do know, then do. But do it right. Otherwise, you may not be doing it long.
Regular Guest
I replaced the cap because an electrican friend was with me, and sugested that the cap was over amping and feed back through the system. Didn't make since to me, but I had it on the truck, so throwed it on. I have traced all the wires, there isn't any bare or melted wires. Nothing going to ground. I went as fare as taking each wire off, set my meter to continuity, put one lead on the end of the wire, then touched ground. No continuity anywhere, with the exciption of the board. I also took the t-stat wires off the board terminal strip. There is continuity between red and yellow. Again, removed a wire off the contactor, or remove the moulex plug, I lose the continuity.Originally Posted by iraqveteran
I checked the contactor with my meter. I have resistance on the coil, the contacts are clean. I just went over to his house(he is only a few minutes away) I have continuity across the contacts with the contacts opened and closed. Could I have gotten a bad contactor off the shelf?
Professional Member
seems that way.....
you checked to ground.....how bout to common. Did you isolate all the wires first?
I fully support the military and the War on Terrorism.
If you don't know, then don't do. If you don't know and still do, then be prepared to pay someone else a lot to undo what you did and then do it right.
If you do know, then do. But do it right. Otherwise, you may not be doing it long.
Professional Member
When you say you have continuity across the contacts, are you referring to the high voltage contacts (l1,l2,t1,t2), or the coil contacts? Because the resistance through the coil contacts would not change wether the contactor is open or closed. Also, if you are not getting continuity through your control circuit for the compressor contactor, did you ohm your LPCO and HPCO?
Professional Member
Then we can help. How do we know if you are not DIY. Read rules.
Do it right the first time.
Regular Guest
Thanks for the help...........or the lack of. I ohmed out the board. There was a few shorted componets on the board.
By the way, I am not a DIYer. I work for a hospital maintaining the high pressure boilers and chillers. Been doing this for nearly 7 years. I didnt think it was the board, due to the board had no sign of being bad. It is ok that you all didn't know how to help me, but you didn't have to get all crazy on me. Hope you all have a great day.
Banned
if you think that they went crazy on you, hang around for a little while and you will see crazy!
as stated apply for pro membership, we would love to "get all crazy" on you in the pro section
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God Speed, Jim. We'll miss you - 2-26-23
Leave your after hours personal life out of it. LOL...we would love to "get all crazy" on you in the pro section
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Professional Member
Who got crazy? lol, I dont know why but when you said that I busted out laughin. I dont even know why it was funny but it was.
Professional Member
Guy's, sounds like ya'll have hurt his feelings! Here I thought everyone was being extra kind! Now that the OP has confirmed that no one else here knows what they are doing, I don't feel so alone! lol
FYI - (OP) There are more smarts here than you can shake a stick at, but rules are rules so you need to get your post count up and move over to the pro forum's. You can't think of a HVACR question that won't get answered in detail there. Question is - Are YOU tough enough?
Banned
Leave your after hours personal life out of it. LOL...
are you having those crazy thoughts again, i thought you got over that!
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God Speed, Jim. We'll miss you - 2-26-23
My doctor says I'm doing much better.are you having those crazy thoughts again, i thought you got over that!
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Professional Member*
You can take the wires off the terminal strip at the board all you want, As long as the stat is still calling for cooling you will continuity between R and YYou would have to take the wires off the stat as well as the board, You will feed through the y circuit all the way outside, Until you pull the wire off the contactor... Also you will never see a board look bad unless it got smoked. And your "Electrician" friend should not be behind you next time you troubleshoot an A/C. The cap "over-amping" would blow your line voltage fuse (That's the term for the higher voltage going to the condenser) And a boiler operator is not a HVAC mechanic
Also. next time before you go parts changingcheck them first, Its real simple, Take the contactor inside to the transformer, With NOTHING ELSE hooked to the transformer apply 24 volts, If it pulls in and doesn't smoke your Transformer, Its good. Of course you could ohm it out but boiler operators wouldn't know how to do this. As far as the stat goes, Take the thing off the wall and disconnect the wires, Jump out the wires, If you still blow your low voltage fuse when the stat is not hooked up, Then you can pretty much rule that the stat is not the problem. Chillers dont have stats maybe that where you got confused. If your brother in law is low on funds, Maybe he should call a pro
These people tried to help you, If you want people to go crazy on you we can easily do so and will enjoy it. If you intend to use this site as the tool and reference it is, Then you got off on the wrong foot.
Rules are rules we cannot help you UNLESS you are a pro, If thats a problem dont flip out, Email the admin or get your pro membership
Regular Guest
Now, that got the people commenting. LOL. I did all the above. I removed the t-stat wires from inside, ohmed the contactor, hooked it up to 24v, didnt pull its self in. The hospital I work at, the boiler tech is the hvac tech. Anyhow, dont want to upset anyone else. I know with that post the people would flock. I read the rules today, which I know should have been the first thing.
That is what had me so flippin confused. The t-stat wires were off inside, and I still had cont. Anyways, I worked it out. Also, with the board: When we have a board go out at work, it is always visible. Admittly, we are talkin about 480 volt 3 phase. I dont work on to many residential units. My line of work is in the commercial side of things, which is a different beast in itsself.
This might be a stupid question, but here goes. How do you get pro status. I looked over the site rules, but didnt find it.
God Speed, Jim. We'll miss you - 2-26-23
Get your post count up to 15 FIRST, then go here.
http://hvac-talk.com/vbb/showthread.php?threadid=116113
Regular Guest
Thanks
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