I have a Gibson self contained GQ3R heatpump that has a defrost problem. My question is, how do you diagnoise a defrost thermostat, and how can you diagnoise the defrost board, or put the board into the defrost mode without the defrost thermostat connected. I think the defrost thermostat is a thermistor, is that correct?
Many thanks.
Everett
If you were a tech, you would know how to run it though a test defrost cycle. Just don't short the wrong terminals or you will be buying a lot more than a DF board..... even if the problem is *only* the DF board.
Thanks Steve for a great answer! Just for the record I was a HVAC contractor in the Nashville, TN area for 18 years and gave it up in
1989 for other interest. I know my way around the equipment very well but am not familiar with the newer "to me" defrost board and defrost thermostat. Almost every heat pump in that era used a different way to do the same thing and it wasn't integrated onto a single board. I can swap parts, but would like to diagnose before throwing parts at it. By the way the board is part# 624633Many Thanks, Everett
Suggest you stick with your other 'interest' and call someone who is qualified.
No offense.
On every board ive worked on, there are self test pins that you jumper to put the unit into defrost initiation and defrost termination modes . Im afraid that there are so many boards out there that a Model Unit brand or part number on the board is of little help. Best thing is to either get a manufacturers checkout procedure sheet or find a local HVAC guy who has worked on these units who wont mind sharing his knowledge with you. In closing, oftentimes when you look at the board there will be 2 or 3 pins that are marked 'Test' near them --- these are most likely the test pins for sending the unit into defrost . I miss the old Ranco mechanical type Defrost Control that was simply to engage defrost as well as troubleshoot .. such is progress i guess. Regards.
Thanks for the reply, I found the answer on the Nordyne site. Nordine is the manufacturer of the Gibson line. There have been a bunch of upgraded defrost boards since the date of manufacture on my unit, but I think the test method is at least the same since my board, as the test method I used was for a newer unit. There is an area at the lower left of the board that has three terminals. They are marked ( T2 - Def
- test ). Using these terminals you put a jumper between T2 and defrost with the unit in heat mode and running, then jump between test and C to enter test mode, removing test - C connection as defrost test starts. To stop test remove jumper between T2 and defrost.
Your right about the old Ranco board, I use to work on all brands and would scratch my head on many ocassion wondering why every manufacturer would do the same thing a different way,
Best Regards
Glad you got your answer. Actually, I wasnt referring to the Ranco Defrot Board, but, the old Ranco E15 mechanical type Defrost Controls as thus :
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