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Old 08-19-2020, 11:16 PM   #1
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A/C - compressor runs but no fan


This is a very old unit. Model 150D60-19, Product: 396DAD....
Symptoms are intermittent, but more frequent now.
1) Thermostat "off", turn fan from auto to on, and will not start fan.
2) Fan does start if I go to auto, and call for HEAT. So fan does power...
3) Fan will not start if cool and either auto or "on".
4) Control board is really a couple of relays - electron B89322B
5) One relay is a R8222B-1109. I believe this to be the culprit since this relay seems to be what is controlling the fan for "ON" and when green is shorted to red/24V
6) This relay seems to be obsolete. What is a good replacement? I see R8222B-1067 as FUNCTIONAL for this relay but seems to have many more spades (7 vs 5). I can't find the logic diagram for the original relay, and not sure how to translate. Seems like this was a SPDT relay.
7) Also... given we are in heat wave, I can make a call to cool and the compressor outside runs. Is there a safe/easy way to bypass the relay so I can just run the fan? Would I jumper across 4-2? I would power off the unit so no 120v in, jumper, then turn on again so fan is always running, then make the call to COOL.

I "think" I found a corresponding wiring diagram. I have attached the diagram (I think).
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A/C - compressor runs but no fan-2013-12-04_012421_396d_wiring.jpg  
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Old 08-19-2020, 11:25 PM   #2
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Re: A/C - compressor runs but no fan


Yes, a 4 to 2 jumper will get it running until you get a part to fix it properly. Check the relay coil for continuity to verify it has failed. It may be a wiring connection instead and you'll have to go looking for the 24 volts it needs.

The fan runs on heat because it doesn't rely on that relay... it has the combo high limit - fan control that was used back in the day.
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Old 08-19-2020, 11:45 PM   #3
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Re: A/C - compressor runs but no fan


Thanks.
When you mean check the continuity are talking about the coil which I guess is 1-3? I assume that should be close to zero. I was thinking it was just stuck so I can make a call for the FAN-ON and then ohm-out 4-5. If 4-5 is low / 0, then that would mean the contact is still closed on 4-5 and 4-2 for the call to fan is not getting "switched"?
Does that make sense? I am just not sure how to check the inductor side for the coil except to make sure it is not "open" between 1-3 - right?
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Old 08-19-2020, 11:52 PM   #4
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Re: A/C - compressor runs but no fan


Yes, 1 to 3 is the coil. You can measure it live to see if there is 24 volts ac on it when the system is calling for cool or the fan switch is in the "ON" position at the thermostat.

Measured dead (with one side disconnected to avoid feedback resistance), it should indicate some continuity... likely around 40 ohms.
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