Water in the Rheem Furnace Electronics


  #1  
Old 08-05-02, 06:51 PM
davek
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Water in the Rheem Furnace Electronics

My A/C cooling coil drain line plugged and water ran down into the furnace electronics. When I shut it off to work on it the blower was running. I dried the electronics out with a hair dryer and tried to re-start it. The blower will not start back up. Both the power lamp and OK lamp on the pc board are lit. The run capacitor is at the bottom of the control box (which had 1/2 inch of water in it). When I removed the run cap, I swear it felt and sounded like it was full of water. Is this possible? If so, would this cause this sympton. Thanks.
 
  #2  
Old 08-05-02, 08:32 PM
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caps

often sound like that, they are filled with oil. see previous posts as to checking the cap, sounds like a shorted board or transformer, do you have a meter?
 
  #3  
Old 08-06-02, 07:59 AM
davek
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That explains the noise. I do have a meter and the cap here at work. What should I check?
 
  #4  
Old 08-06-02, 08:45 AM
bigjohn
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Short across the terminals to make sure the cap is discharged. Using an analog ohmeter, place one lead on each terminal. I don't remember the Rx scale to use, so you might have to try a couple. No reading= open cap, 0 ohms= shorted cap, a good cap will cause the meter needle to swing towards 0 and then back towards infinity. Each time you go to apply the leads, discharge the cap first.
 
  #5  
Old 08-06-02, 08:49 AM
davek
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Checked the cap with a multi meter with cap check. Measures 7.47 uF (spec on side of cap says 7.5). Seems ok, even though terminals are rusty from the water.

More on the symptoms: 1992 Rheem Furnace
- thermostat set on fan on and off (no heat or cool), blower won't run. Circuit bd is getting power because the pwr and ok lights are lit.
- thermostat set on fan on and cool, compressor turns on outside, I can hear the freon circulating, still no blower.
- thermostat set on heat and fan on, nothing on (no blower, no induced fan, nothing).

Luckily the weather has turned much cooler now, but I only have a couple days.

I have seen other posts regarding the circuit bd and I wonder if the water did it in. I seem to only find repair companies here in Cincinnati, but I don't see where I can purchase parts?

Any other suggestions?
 
  #6  
Old 08-06-02, 08:53 AM
davek
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Thanks. Checked with digital ohmeter and says OL. I assume that means infinity, which is a good thing, right? I will see if I can find an analog meter to verify.

Thanks again.
 
  #7  
Old 08-06-02, 09:38 AM
bigjohn
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Infinity would mean it's open. If the cap tester is showing 7.47 uf , then it's probably ok. If your not getting the blower and also not getting the inducer motor in heat, you probably have blown a board or module. Did you run the heat temperature setting up high enough? BTW- are you testing the blower with the blower section cover off? A lot furnaces have a door switch which will prevent the blower from coming on with the cover off. There should be a Johnstone Supply where you can buy generic parts, but you might have to go to a Rheem dealer to get a board that was special designed for Rheem.
 
  #8  
Old 08-06-02, 09:39 AM
davek
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More info...
Can't find an analog meter. Checked with another meter (Fluke 87). Using ohmmeter, resistance starts at 5 Mohms and climbs higher. OK/not OK?
 
  #9  
Old 08-06-02, 09:45 AM
davek
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Sure seems like we are posting at the same time!

The blower door does have a switch which I depress whenever I test it (although I don't leave it closed for long, does it matter?).

Thanks for the Johnstone Supply lead. Unfortunately, they only sell to dealers. I will double check the heat setting to see if it will start.

Are there any components on the circuit bd that may require more time to dry out and may be ok later?
 
  #10  
Old 08-06-02, 11:04 AM
bigjohn
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Hi Dave:

It sounds like the cap is probably ok. I have several Rheem gas fiurnace manuals and probably have your model. Take some test meters home with you tonite and then post the furnace model & serial numbers. Then put the cap back in place. If nothing else, we might be able to get the indoor fan running off an extension cord which will at least give you the cooling back. BTW- the blower door awitch has to closed full time in order for the furnace circuits to keep working.
 
  #11  
Old 08-06-02, 01:07 PM
davek
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New cap didn't help

Home now. Replaced cap anyway and no change. Model number is RGED-07EMAGS, s/n BU50302RM17920946. Tried again to get heat. Set on heat, fan ON, tape on blwr door, still no blower. Call local distributor about avail of ckt bd, $150, don't recommend diy due to differences between wiring to bd. Have multimeter at the ready. What should I ck?
 
  #12  
Old 08-06-02, 01:54 PM
bigjohn
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ok, it looks like you have a 90 plus furnace with a Honeywell board. Do you see terminals, R,W,Y,G,C? With the blower door switch closed, turn the thermostat FAN switch to ON and see what voltage you have between G and C. Should be 24 voilts.
 
  #13  
Old 08-06-02, 02:00 PM
davek
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23.6 v although it seems to wander between 23-25.
 
  #14  
Old 08-06-02, 02:05 PM
bigjohn
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YEAh, with a digital meter, it's going to gyrate some. 24 volts is good, now look on the board for terminal L1 [should have a black wire on it] and a terminal called Nuetrals [should have at least one wire on it] Wgat voltage do you have between L1 and Nuetrals?
 
  #15  
Old 08-06-02, 02:07 PM
davek
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Starting to wish I had a ranch instead of a 2 story. 122 v.
 
  #16  
Old 08-06-02, 02:14 PM
bigjohn
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120 volts is good. Now look for two adjacent terminals, one is marked COOL and the other HEAT. also, look for a white wire that comes from the fan motor to the nuetrals terminal. Ensure that you still have 24 volts between G and C terminals and next test for voltage between Cool and Nuetrals and then Heat and Nuetrals and tell me the results.
 
  #17  
Old 08-06-02, 02:22 PM
davek
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With the thermostat on Fan ON and Cool with temp set below room temp:

Still 24 v G & C. White from the motor goes to the Run Cap. Ck'd and found 0 v between Heat and Neutral or Cool & Neutral. I had checked this earlier and assumed that this meany that the motor was not seeing voltage. This, I assume, tells me it is NOT the motor, but the board?
 
  #18  
Old 08-06-02, 02:34 PM
bigjohn
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Unfortuneately, it looks like it's the board. We're getting power to the board and we're getting control voltage the right terminals but we're not getting power back out of the board which means the relays on the board are bad. To prove our work, turn the t-stat to off and shut off the power to the furnace. Find a fairly heavy extension cord, one with #14 wire will be ok but not a lamp cord. Remove the wire from the HEAT terminal and tape it up. Remove the wire from the COOL terminal and also the wire that goes to the motor from the nuetrals terminal. Connect those two wires to the end of the extension cord and then plug it in. If all is ok with the motor, it should start right up. Unplug, take the tape off the door switch and put the cover back on the furnace. Turn the furnace back on, plug in the fan and set the t-stat for cooling. This will at least get the cooling working until you can get a new board. Don't forget to write down which wire goes to cool and heat before you remove them.
 
  #19  
Old 08-07-02, 05:22 AM
davek
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Talking Success!

I wired the motor directly to an outlet and it fired right up. I then talked to my neighbor (who happens to be an Electrical Engineer) and he suggested that there may be corrosion on the back side of the board due to the water. I removed the ckt bd mounting screws and was able to rotate it out without removing wires. After some cleanup of water residue, I noticed that one of the board traces near the bottom of the board looked funny. I scraped the green film off to find a damaged trace. A continuity check revealed that the trace was open. I followed the trace to the relay that we assumed fired the blower motor. I soldered a jumper (phone cord wire) between two solder joints on either side of the defect. Turned the power back on and everything works fine! Even tried the heat and the induced fan fires up, the igniter lights, burner lights, and blower kicks on. A/C works perfect, too.

Thanks for all your help.
 
  #20  
Old 08-07-02, 05:30 AM
davek
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Question Clogged Drain

Now, to fix the original problem (the drain pipe clogged). Do I need a trap in the line? It doesn't seem like it should because both ends are open to atmosphere. The coil drain is on the positive side of the blower. I would like to get rid of the trap because it seems that it will be likely to clog easily. I will also probably put a T in with an accesscap so I can clean it out now and then.
 
  #21  
Old 08-07-02, 06:15 AM
bigjohn
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Dave, you're pretty handy! You might want to try various safety shut down scenarios in heat just to ensure that the furnace will shut down in the event of a malfunction. As for the trap, a T with a cap ahead of the trap is a good idea, but I would still keep the trap to eliminate the possibility of a venturi effect at the drain opening preventing the water from flowing out. The T will allow you to pour in some bleach periodically.
 
  #22  
Old 08-07-02, 06:21 AM
davek
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Good advice on the safety shutdown scenarios. Any in particular?
 
  #23  
Old 08-07-02, 08:42 AM
bigjohn
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Pull the power to the inducer motor and turn on the heat it the burners should not lite, ditto with pulling the power to the ignitor. Shut off the gas and see if it shuts down when the burners don't lite. Pull the power to the blower motor and turn on the heat. The furnace should heat up, and the limit switch should open shutting the burners off and also shift the blower motor to full time running. Alternatively, completely block the return air and try the overheat test. You need to know and not next winter if all of the board functions are intact.
 
 

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