Split System, Bad Relay?

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Old 04-06-14, 10:09 AM
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Split System, Bad Relay?

South FL location. I have an 8 year old split system central air unit. Rheem, model 042JBZ.
All was fine until a few weeks ago when I noticed that the unit was occasionally short cycling. On for a minute, then shutting off. After doing this once or twice it would cycle normally and cool to the set temperature. The on-off cycling has continued with increasing frequency.
Yesterday the unit wouldn't shut off and I noticed the house temperature was 3 degrees below the thermostat temp I had set. This morning, the same thing and I have to now shut the unit manually.
Thinking it was just a bad thermostat, (it's 4 years old, model 6020), I contacted Rite Temp support. They told me to disconnect the yellow wire and if the unit continues to run it is likely a bad relay. Well, the unit did continue to run. So, turning to the powers that be here, what is my course of action at this time? Not an AC savvy guy, so is this a fix I can do myself?
Thank you!
 
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Old 04-06-14, 12:30 PM
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Post the 4 letters before 042JBZ in the model number so we can have some idea if this is a heat pump or conventional 3 1/2 ton unit.
 
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Old 04-06-14, 01:05 PM
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That would be RAND, model RAND-042JBZ
 
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Old 04-06-14, 02:13 PM
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http://www.rheem.com/docs/fetchDocum...0-87ddcc3ddf51

Okay, so you have a conventional 15 SEER split system.

Was the yellow wire connected to the Y terminal?
Did you notice if the stat wire had a large hole behind the stat that might allow outside air to affect the thermostat operation?

Many furnaces have a time delay before the fan shuts down.This might have an impact on your test. Does the fan instantly turn off when you manually turn off the stat?
 
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Old 04-06-14, 03:20 PM
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Yes, the yellow wire is connected to the Y terminal. Also, the red wire is connected to the RC terminal, and the green wire to the G.
And, yes, there is a time delay before the fan shuts down. When I manually shut off the thermostat there is always a delay of about 30 seconds. When I pulled the yellow wire the AC continued to run for 2 minutes, at which time I concluded unit was not going to shut off.
 
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Old 04-06-14, 06:03 PM
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You will need to trace the short.

You can try removing the yellow wire from the stat at the air handler.
 
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