Fan relay

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  #1  
Old 12-12-02, 04:20 PM
jdcuzmar
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Unhappy Fan relay

I have a Comfortmaker Air Conditioner & Heating. Model DEBA005GB.
The blower fan runs constantly even when the unit is in the OFF position on the thermostat. The burner turns ON and OFF properly, so as the condenser unit outside. I have replaced the thermostat and the problem persists.
I was told that the fan relay is stuck closed. I have tested the fan relay and the normally open set of point on the relay has NO continuity, thus, is it OK to rule out the blower fan relay as the cause of my problem?

What else can I do? Or do I need to call a technician?
Please help. We are freezing!
 
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Old 12-12-02, 05:00 PM
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jd,

if the normally open set of points is open, and the fan wire is connected to it, then the fan is probably getting power from the limit switch being stuck. how old is it? it may be a dial type. there would be a rectangular cover over it. you seem pretty handy with a meter, can you follow the path of electricity and see where it is coming from?
 
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Old 12-12-02, 08:00 PM
jdcuzmar
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limit switch

The unit is 14 years old, and it does not have a dial type.
Starting from the blower motor, there are three wires:
1. BLACK goes to point 4 which is normally open to point 2.
2. RED goes to point 6 which is normally close to point 5.
3. YELLOW unites with another BLACK wire( which goes to the transformer) . Then it goes to the power supply 208/240V.
Then branches to another BlACK wire which goes to the limit control (is it another terminology for limit switch?). As you can tell, I followed YELLOW all the way to the limit control checking for continuity, and there is a resistance of ~20 Ohms....No continuity for the limit control/switch. Is the limit control the guilty one? I hope so!

Also, I have been doing some maintenance to the blower. Cleaning the blades, oiling....the instructions say to add 5 drops of SAE 10W motor oil and I have SAE 10W-30 motor oil which I use for my car. Can I use the same oil?

Finally, I had to disconnect the capacitor which has two terminals, and I did not labeled them . Does it matter which one goes where?
 
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Old 12-13-02, 01:43 PM
george7197
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Yup I think your on the right track. Sticking limit be sure to replace it with one with the same probe lenght (very important). Most likely you have a honeywell. I've seen those at home depot before. Wire it the same way and MAKE SURE if the one you have now has the 24/120V tab removed to remove it on the new one. Otherwise you'll burn out everything on the controll side of your system and have to replace everything $$$$-- gas valve, t-stat, transformer, board/relay, & A/c contactor. I've seen a DIY guy do it before he called me. I felt kinda bad for him.
 
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Old 12-13-02, 01:46 PM
george7197
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Oh, forgot if the two wires on your capaator are both brown U can interchange them. DO NOT put car oil into your electric motor! Buy a high grade machine oil if you want your blower to last.
good luck
 
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Old 12-13-02, 04:36 PM
jdcuzmar
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thermodisc

My limit control does not have a probe. It is a thermodisc (~ 1 inch in diameter). I removed it from the furnace and checked for continuity and it does not show continuity, so it needs to be replaced...right?
 
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Old 12-13-02, 05:48 PM
jdcuzmar
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hardware online

the local A/C and Heating companies do not sell electrical parts unless you are a licensed technician. Where in the Web can I buy by thermodisc? Help!!!!!!!!!!!!
 
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Old 12-13-02, 05:59 PM
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go to

heatcoolparts.com, hoped we helped you.
 
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