6535 Basement Heatpump

tennsmith · 09-24-2016, 10:01 AM

I have a strange A/C problem. To get my unit to come on, I have to set the thermostat some 20 degrees or so below the room temperature. I have already tried replacing the thermostat, and the new one behaves exactly as the old one, so I'm ruling that out. Both compressors work and the unit shuts down when the room temperature equals the set temperature. Has anyone else experienced a situation like this? Do I need a new PC board in the unit? My green light on the board is steady green, not flashing.

Duner · 09-25-2016, 09:36 AM

This service manual has fairly extensive troubleshooting procedures. There are LEDs on the control board that will help you isolate the problem. You can get at the control board by opening up the Winnie side cover and then one or two screws to remove the black panel on the left side.

Good luck,
Bill
https://docs.google.com/viewer?a=v&p...GI4N2U4N2MzODE

bluepill · 09-25-2016, 09:42 AM

Check the thermostat manual and see if it has an adjustable "Differential". That is the number of degrees between turn-on and shut-off.

If it is adjustable, try changing it. There might be a software/firmware bug that goes nuts at a specific diff. setting.

tennsmith · 09-26-2016, 08:40 AM

Although I do not fully understand why, the unit now appears to be working OK. Being a "digital" thermostat, I was expecting instant results, i.e. when the set temperature is below the ambient, the unit comes on...but this was not happening. I know there are built in delays in the system, but those too were exceeded from a time standpoint. All I can figure is that the thermostat itself has some delay before sending the "on" signal to the unit. I let it run thru 5 on/off cycles and it was controlling the temperature to the set point +/- 1 degree....so I declared it "healed" and moved on. Thanks for your replies.

dc8cappie · 09-26-2016, 01:29 PM

Since I had my unit repaired(no cooling but stilled had heat pump) the start time is about twice as long as prior to the repair. How knows way, but, I don't care as long as it works.

tennsmith · 09-27-2016, 07:54 AM

I'm with you dc8cappie, "works" is the key word, not time. :-)

lakewoodpaul · 09-27-2016, 08:53 AM

Quote:

Originally Posted by tennsmith

Although I do not fully understand why, the unit now appears to be working OK. Being a "digital" thermostat, I was expecting instant results, i.e. when the set temperature is below the ambient, the unit comes on...but this was not happening. I know there are built in delays in the system, but those too were exceeded from a time standpoint. All I can figure is that the thermostat itself has some delay before sending the "on" signal to the unit. I let it run thru 5 on/off cycles and it was controlling the temperature to the set point +/- 1 degree....so I declared it "healed" and moved on. Thanks for your replies.

There is about a 20 second delay on my unit, you can hear the thermostat click, then 20 sec. later the ac comes on.

groundpilot · 09-27-2016, 04:07 PM

I've noticed that when using the heat pump, there is about a 4 degree heat differential required for it to cycle back on. On a cold day, a 4 degree day or night can feel significant. Also, when it does cycle back on, it blows a lotta cool ( read "cold") before it warms up. But, hey . . . It works! Now that we've installed a fake fireplace, the heat pump seldom operates. The MCD shades, duo-pane, really dark tint windows have made a huge difference in retaining the heat, and rejecting the cold.