Heat pump

Bob_2

Unfortunately, non of my information lists any detail about the GE control. The diagram on the unit should show the switching, if the diagram is intact. Your best bet would be to contact Lennox direct at 800-453-6669. Be prepared to wait on line for some time, as they get real busy nowadays. Best to call early in the morning, they are manning the lines from 4:30 AM PST to 4:30 PM PST.

Anthony Mobilio_3

Heat pump

Went a call today for a split-air cooled heat pump, the question I have is regarding the defrost timer. Its a very old heat pump, Lennox unit. What is the best way to test the defrost operation? The timer has 110 v to the # 1 terminal the clock was turning, the # 3 was a blue wire going to the defrost relay, the #4 was common with 110 v to it. the #5 went to one side of the defrost thermostat the other went to the defrost relay. If the # 4 and #5 terminals were jumped out would this put the timer into defrost (considering the DT would be in a closed position) or is there a better way to do this.


Thanks A

Bob_2

Heat Pump

What model HP are you working on?? I have access to thirty years of service manuals for Lennox, so I may be able to send you something...

Anthony Mobilio_2

The timer is a G.E. mod#3asp18b6ab
The unit mod# is hp18-261v-7p

Bob_2

The original HP18 used the GE control. This was a time initiated/time terminated control. Later on there were some issues identified with that control, and went to a Paragon time intiated/pressure terminated control that proved far more reliable. Troubleshooting the GE should be just a matter of advancing the control to a defrost period, and watching to see that it comes out of defrost. Additionally, advance the control to just before the defrost, and make sure it goes into the defrost "unassisted". Either way, since there were some issues with the time/time configuration, I would get a new control for it. Or better yet, get them a new unit, as you just know that when you retro-fit this control, that 15 year old compressor is going bad a week later!! The HS18 was a "tract" model heat pump, with no frills! Out here in California, it would have been swapped out a long time ago, just for efficiency sake.

JimGPE_3

Did you notice he mentioned a defrost thermostat? That must be in the cct, too, perhaps to keep the unit from defrosting when the oa temp is 50F or something. The defrost stat will need to be checked, too, I would think.

My guess is for the unit to go on defrost both the timer and the stat would have to "make" (i.e. they are wired in series).

Any data on that?

Anthony Mobilio_3

Thanks guys for the help. Is there a good book on servicing and trouble shooting heat pumps.

Anthony Mobilio_3

On this control when it went into defrost what legs would get hot 3 and 5,would 5 get power from common(#4) or from #1.