Control board - Purple 3 fuse keeps blowing

[PelicanPines]

Went to turn on my downstairs zone today and it worked for about 1/2 an hour then "Pop'ed" off. A quick diagnostic approach identified the purple blade fuse on the control board was blown. Replaced it... turned it all back on... it blew again as soon as "Cooling" was requested. No error code was thrown.

H E L P M E !!!

What could this be ???

 

[bczygan]

It's an electrical problem......You're gonna need a bigger hammer!

Bill

 

[PelicanPines]

It's an electrical problem......You're gonna need a bigger hammer!

Bill

uhm yea... is it the control board... is that something i can replace myself... or

WHEN that fuse blows... it means "Insert something here" and i need to fix that.

 

[bczygan]

I'm not an electrician or electronics expert, but when a fuse blows, it's usually an electrical power problem. Where in the power circuit, on board or off, is the question.

Let's see if some sparkies or A/C guys can help.

What's the make and model of equipment?

 

[PelicanPines]

Took Pictures of everything... I have the blade fuse OUT of it's location on the control board... I circled the spot in RED. It's on the absolute lower LEFT side of the board... next to the 12 gang connector. To repeat... the fuse is purple and has a 3 on top.

 

[pepi]

I will say this the discoloring of the board and IC are not a good sign...... BTW sent from my Mac.

Control board is replaceable, if sold

 

[gregtwojeeps]

No pro help here. That is your main fuse for the whole control board, could be anything on the board bad or anything that is controlled by the board. The fuse needs to be good in order to even get a flashing "code" light so you could troubleshoot the system. It looks like my furnace board...

I guess you could do what the hvac guy did to the board on my gas furnace ( note small copper wire jumper bottom right of board that he replaced the fuse with )

Get the model number from your unit and go to repairclinic.com . Type in your model number for parts. Also need the number on the control board if you or your tech find you need a board. Even Amazon has control boards ...make sure its the right number board so your pin connectors will work. . $130 bucks + or _ Good luck

 

[brewchief]

Disconnect the low voltage wire that runs to the condenser outside, it will be connected to Y and C, replace fuse and see if furnace runs the blower properly. If so inspect the low voltage wire outside looking for damage, weedwackers tend to do damage pretty often.

Sent from my XT1254 using Tapatalk

 

[PelicanPines]

Disconnect the low voltage wire that runs to the condenser outside, it will be connected to Y and C, replace fuse and see if furnace runs the blower properly. If so inspect the low voltage wire outside looking for damage, weedwackers tend to do damage pretty often.

Sent from my XT1254 using Tapatalk

Have that whole area paved around the condenser... but will check. Will also look up the control board replacement. $130 is better than the $500 a pro will charge.

 

[Dagny]

brewchief nailed it

 

[Dagny]

Now Now if you lived here I would do the whole job for less than 250.

 

[PelicanPines]

OK... so far... I checked the wires outside... all look good but i have not done the exact diagnostic Brewcheif suggested yet. The system can be powered with a green blinking light provided "Cooling" is not called for. When i press the "last" button to see if there is a stored error... there is none. It sits there just fine with a slow green blink (normal) until Cooling is requested and POP... that main 3amp purple is toast.

Like I said earlier... it did run for 1/2 an hour fine with cool air at the vents...

Guess this means i need a new control board (i'm guessing)... will order one in the morning if nobody else has any other ideas.

I will do the test Brtewchief suggested tho... first.

Somebody elseware suggested I run the system FAN ONLY and see what happens... I need more fuses for that... I'm out till the morning.

 

[6t7gto]

Get the number off the board and check ebay.
I have 3 rooftop units. All my boards are the same...so I picked up spare boards from ebay. About $50.00.
Changed one out today.

 

[gregtwojeeps]

.......................

 

[PelicanPines]

In the end... if i need a control board... anybody recommend NorthAmericanHVAC.com ???

 

[brewchief]

A board failure could cause your symptoms but it's not a common failure to do what it's doing.

I would bet money that it's either a bad control wire or a bad contactor, first try it with the wire disconnected at the furnace and if it's OK then disconnect it at the contactor in the outside unit and reconnect it indoors and see what happens, this will narrow down where the problem is.

If you have a meter you can simply disconnect both ends and check for continuity between the wires, the control wires aren't that tough so a short isn't that uncommon.

 

[PelicanPines]

A board failure could cause your symptoms but it's not a common failure to do what it's doing.

I would bet money that it's either a bad control wire or a bad contactor, first try it with the wire disconnected at the furnace and if it's OK then disconnect it at the contactor in the outside unit and reconnect it indoors and see what happens, this will narrow down where the problem is.

If you have a meter you can simply disconnect both ends and check for continuity between the wires, the control wires aren't that tough so a short isn't that uncommon.

Ok that I can do. Your advice is exactly what I was looking for. Thank you.

 

[BillK]

pp,
Without a circuit diagram to tell you what item is powered by the fuse, you are just spinning your wheels. Yes you can shotgun a board but what if it doesn't fix it ???? Then you have wasted a bunch of money. You have two choices the way I see it:

1. Find a circuit diagram and learn how to troubleshoot the problem to find out what is causing the fuse to fail or ...

2. Pay someone to do it. This option may actually save yo money in the long run.

 

[PelicanPines]

I hear you ... I will definitely do a deeper diagnostic.

 

[zmaxmotorsports]

Disconnect the low voltage wire that runs to the condenser outside, it will be connected to Y and C, replace fuse and see if furnace runs the blower properly. If so inspect the low voltage wire outside looking for damage, weedwackers tend to do damage pretty often.

Sent from my XT1254 using Tapatalk

Start with the simple stuff 1st.
Is it a seperate system for the basement,or are you talking about zoned duct work?

 

[larry4406]

I have had thermostat wires short and blow the fuse

 

[LS6 Tommy]

Brewchief pretty much nailed it. Something in your cooling control circuit is grounded or shorted.

Tommy

 

[PelicanPines]

Yea works fine on fan only. Can't see the issue will call in a pro. Thank you all !!!

 

[Big Daddy Chop Shop]

My honest to goodness bet is a bad contractor coil. But it is impossible to diagnose via the internet. FWIW, the discoloration on those particular boards is not abnormal at all. it is rarely a sign of a bad board on these units. Lots of them get changed with the "shotgun" approach for this reason though.

Pros seem expensive, until you hire an amateur first.

 

[Milton Shaw]

A common problem is for mice/rats to chew the wires somewhere between the inside unit and the outside unit. I have even seen them chew the wires from inside unit to thermostat so check wires very carefully. If you have some extra wire just run it from thermostat to unit and then to condenser and try it before you spend money on a board. It may end up being easier to relocate the thermostat then get new wires to it if that is where the problem is.

 

[MTW]

"Pros seem expensive, until you hire an amateur first."

+++

 

[zmaxmotorsports]

Check the thermostat wire between the house and outside condensing unit,Previous owner may have had a dog that liked chewing on things.

 

[PelicanPines]

My honest to goodness bet is a bad contractor coil. But it is impossible to diagnose via the internet. FWIW, the discoloration on those particular boards is not abnormal at all. it is rarely a sign of a bad board on these units. Lots of them get changed with the "shotgun" approach for this reason though.

Pros seem expensive, until you hire an amateur first.

DING DING DING... you my friend are correct. It was a bad Contactor Coil. A $15 part... but the pros charge $93 for it PLUS $99 service call and some tax... for a total of $199.**

Thanks everyone... I probably could have done it myself after watching him do it... I can say... if either of the other 2 zones need this fix... it will be me doing it. Something like that... i have to watch it once...

He did mention all the wiring issues you all mentioned as well but saw the whole setup i have is clean and protected so he went right to the Contactor.

 

[danski0224]

I'm sure that whatever you do for a living is overpriced too...

 

[PelicanPines]

Spoke too soon... It's not too hot today so in order to make sure the unit turned on after fixing the Contactor... we lowered the temp on the thermostat to something weird like 66 degrees and it did kick on... all seemed fine... the service professional left with my $199.

Put a thermistor at a vent after waiting 20 minutes... it's blowing the same temp as the ambient air in the room.

Upon further investigation... I discovered he left the connections UN DONE on the screw terminals when he was diagnosing the system. They were dangling... good thing i took BEFORE pictures for you fine folks.

I was able to figure out where the unconnected wires went and connected them.

I may give a ring to their office in the morning and mention that brain fart to them.

 

[PelicanPines]

Now i'm getting 67 degree air at the vents with 77 in the room... at least it's cooling now.

The other zone with the same unit gets 66 degrees on the closest vent to the air handler. My third zone which is a different system completely blows 62 degrees.

Do those temps make any sense at the vents??? I'm R22 on the two big zones... no idea on the third.

 

[LS6 Tommy]

DING DING DING... you my friend are correct. It was a bad Contactor Coil. A $15 part... but the pros charge $93 for it PLUS $99 service call and some tax... for a total of $199.**

Thanks everyone... I probably could have done it myself after watching him do it... I can say... if either of the other 2 zones need this fix... it will be me doing it. Something like that... i have to watch it once...

He did mention all the wiring issues you all mentioned as well but saw the whole setup i have is clean and protected so he went right to the Contactor.

A 20 or 30 Amp comtactor is NOT a $15.00 part. $99.00/hour is cheap compared to some (most) other trades...

More importantly, I'm glad you're up and running.

Tommy

 

[PelicanPines]

A 20 or 30 Amp comtactor is NOT a $15.00 part. $99.00/hour is cheap compared to some (most) other trades...

More importantly, I'm glad you're up and running.

Tommy

Really???? I looked at Amazon ... they were like $15. My bad ... doesn't matter. He had the part, fixed it.... left a pair off that I had to do but I'm so not complaining on the price... it's just I would now be able to do that one myself in the future.

 

[brewchief]

A 20 or 30 Amp comtactor is NOT a $15.00 part. $99.00/hour is cheap compared to some (most) other trades...

More importantly, I'm glad you're up and running.

Tommy

I can buy 30 amp contactors for $6.83 and 40s for 10$ right now, it's the $40k service truck with $20k in stock driven by the tech making a decent wage with decent health insurance and received better then average training that drives the cost up.

PelicanPines keeping a spare contactor and maybe even capacitors for your units might not the worst idea ever.

 

[LS6 Tommy]

I can buy 30 amp contactors for $6.83 and 40s for 10$ right now, it's the $40k service truck with $20k in stock driven by the tech making a decent wage with decent health insurance and received better then average training that drives the cost up.

General purpose or definite purpose/OEM replacement? Parts sure are less expensive where you are. I just bought a replacement COIL for a 40A contactor from United Refrigeration. Tax exempt for the school system, with a discount it was $35.00. I certainly won't argue the rest of your points. Paying inventory taxes on the stock you have to keep drives the cost up, too.

Tommy

 

[PelicanPines]

All I know... with out this thread I would have not been able to fix his mistake... when he forgot to reconnect those two wires on the control board.

It's all you guys fault I almost appear to almost know what I'm doing.

Thank you all again.

 

[brewchief]

General purpose or definite purpose/OEM replacement?

Universal replacements made in China or someplace close to China.

Anything 3 phase or that has to have OEM replacement gets much more pricey.

 

[LS6 Tommy]

Universal replacements made in China or someplace close to China.

Anything 3 phase or that has to have OEM replacement gets much more pricey.

No doubt. You're still getting much better pricing than we do around here.

Tommy

 

[PelicanPines]

I did notice the OEM was open around the coil... the new one is totally sealed. He even commented this new one is a much higher quality brand... sadly I didn't take note of it and he took the box and OEM

 

[danski0224]

I can buy 30 amp contactors for $6.83 and 40s for 10$ right now, it's the $40k service truck with $20k in stock driven by the tech making a decent wage with decent health insurance and received better then average training that drives the cost up.

PelicanPines keeping a spare contactor and maybe even capacitors for your units might not the worst idea ever.

Why do all that when you can get free troubleshooting on the innernet?