Gas and Oil Home Heating Furnaces - HELP!!! 3 amp fuse blows on control board of Rheem
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carrac89
10-28-09, 10:51 AM
I have a Rheem classic 90+ and the 3 amp fuse on the control board (part number 62-24140-02) keeps blowing. I had a technician come and inform me that the fuse blew, so he replaced it, and it was fine. I noticed the fuse blew again, so I replaced it with the same 3 amp fuse (tech left me 3 extras) - but I have since gone through all through in a matter of a month. I noticed it blew when I switch from heat to AC, but now, it just blows within minutes when I put the fuse in. Any ideas. I'm out of fuses - LOL and before I call the tech back out, I'm trying to get some answers.. HELP!!!
mbk3
10-28-09, 04:15 PM
Well typically a low voltage fuse blows, the cause is a short in the thermostat wiring. Look for any bare wire going thru the cabinet. Also take the tstat cover off and make sure none of the wires are touching each other where they don't look like they should.
ecman51`
10-28-09, 05:23 PM
I noticed it blew when I switch from heat to AC, but now, it just blows within minutes when I put the fuse in. Any ideas. I'm out of fuses - LOL and before I call the tech back out, I'm trying to get some answers.. HELP!!!
When it blows now, within minutes, could it be that you are trying to install the fuse right when the thermostat is calling for cool?
The short might be outside also, on the low voltage wire. Maybe a mouse got in where the contactor is. Or chafed/cut wire insulation and hitting metal.
When it blows now, within minutes, could it be that you are trying to install the fuse right when the thermostat is calling for cool?
The short might be outside also, on the low voltage wire. Maybe a mouse got in where the contactor is. Or chafed/cut wire insulation and hitting metal.
SeattlePioneer
10-28-09, 05:33 PM
I had a technician come and inform me that the fuse blew, so he replaced it, and it was fine. !
This is the service provided by a marginally competent repairman --- and that's being generous.
The fuse is just the symptom of the problem. The repairman's job is to identify the cause of the problem. But that would take some work and some skill.
Now you are doing the same thing as the repairman.
You need an ohmmeter or multimeter that measures resistance and continuity and the skill to use it. You need to connect it to each wire going to the thermostat and also to the furnace cabinet ground to identify when a dead short occurs. You then need to carefully inspect the wires to find out where they are being pinched and cut by sheet metal.
As described in an earlier post, that is the most common cause of blown fuses. If you are satisfied the thermostat wires aren't the problem, you need to do further diagnostic work on the furnace low voltage wiring to see if a short is occurring there. That can take some skill to do.
Usually you can get the type of fuses used in furnaces at auto part supply stores if you take one of your burned out collection in as a sample.
This is the service provided by a marginally competent repairman --- and that's being generous.
The fuse is just the symptom of the problem. The repairman's job is to identify the cause of the problem. But that would take some work and some skill.
Now you are doing the same thing as the repairman.
You need an ohmmeter or multimeter that measures resistance and continuity and the skill to use it. You need to connect it to each wire going to the thermostat and also to the furnace cabinet ground to identify when a dead short occurs. You then need to carefully inspect the wires to find out where they are being pinched and cut by sheet metal.
As described in an earlier post, that is the most common cause of blown fuses. If you are satisfied the thermostat wires aren't the problem, you need to do further diagnostic work on the furnace low voltage wiring to see if a short is occurring there. That can take some skill to do.
Usually you can get the type of fuses used in furnaces at auto part supply stores if you take one of your burned out collection in as a sample.