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airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8134
Experience:  Furnace, A/C and heat pump specialist.
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I have 2 Tappan heat pumps. Both have same issue. Air handler

Customer Question

I have 2 Tappan heat pumps. Both have same issue. Air handler does not always shut off. It does shut off as expected most of the time, maybe 80-90%. If, when air handler fails to shut off, I move fan control from auto to on and back to auto, air handler shuts off. Started during cooling season, continues in heating season.

I changed one thermostat, problem continues.
Submitted: 5 years ago.
Category: HVAC
Expert:  airheatman replied 5 years ago.

airheatman :

You most likely have a fan relay in the air handler sticking on occasion.If you will provide me me with model numbers of indoor units,I will check and see if the relays can be replaced independantly from the control board or if they are integrated inot the control board

Customer: replied 5 years ago.
Basement unit
Model: B3BM-042K-B There is a wrinkle in label - might be B38M-042K-B
S/N: B3B010403343

2nd unit, also Tappan, was installed at same time, about 2002. It is in attic, accessable, but a pain in the butt - get out my extension ladder, enter through outside access, crawl over to unit where there is plenty of space and headroom. Unfortunately it is most unpleasant outside right now. Hope they are similar.
Expert:  airheatman replied 5 years ago.

Click on this to see the location of the relay:

Part Number is XXXXX

You can purchase online here

Please remenber to ACCEPT answer or I do not get paid.Thanks again

Customer: replied 5 years ago.
Nice answer. Links are good.

Is it odd that both units developed same problem at same age?
Expert:  airheatman replied 5 years ago.

Yes, Tappan is a Nordyne company.These little plastic relays are notorious for stcking.They open and close open and close until little contacs inside start sticking

airheatman and 2 other HVAC Specialists are ready to help you
Customer: replied 5 years ago.
Thank you. Parts ordered from link.
Customer: replied 5 years ago.
Imagine my surprise! I'm not so satisfied now. Today I went to install replacement relays. They are not a direct replacement for existing. Existing parts are # 621867, with 6 terminals (8 connected wires). Recommended part # 621931 has 5 terminals. Existing transformer output is 24VAC while new part calls for 28 VDC.

I rechecked heat pump model number - correct. Both units have same relay.

Some parts on parts list are correct, motor and transformer for examples. But looking closely, the parts list says control board rather than relay for both units. But both units do have a relay. Perhaps this revised spec only applies to newer units?
Expert:  airheatman replied 5 years ago.
Sorry you are having difficulties.My recommendation would be to call the company you ordered the relays from.Explain that they are still in box,never installed and incorrect for your unit. Provide them with serial number and perhaps they can verify exactly what relay your unit uses.One of the problems is manufacturers are constantly changing parts used .Even on exact same model numbers for example ,often they will use glow bar ignites on a run of gas furnaces and spark ignites on the next.Usually by the serial number,a parts supplier can verify which you need.If they cannot verify, they should accept for refund and you can call a local Nordyne dealer to get the correct part.