Compressor shuts off within 5 minutes with cold start up, then runs fine?

Fathompin · 11-11-16, 12:21 PM

Hi there.

What would I look for to fix a geothermal compressor that shuts off within 5 minutes of initial start up from cold, every time, then after a 10 minute wait will start up and run fine for hours. High Pressure and Loss Of Coolant signals are good going to control board, nothing much else going into control board. I suspect the compressor's own thermal shutoff, if so what is a course of action? Compressor discharge temp stays around 195 F. This is a new old stock system that is 8 years old and just getting used for the first time. Thanks.

stevehull · 11-11-16, 12:50 PM

Bad start capacitor? Easy to check it. I have seen similar odd things happen and replacing the capacitor worked.

Let us know.

Steve

Fathompin · 11-30-16, 06:28 AM

I learned quite a bit from this experience. Here is the resolution:

A little low on freon triggering FP1 (freeze protection). When I first received the unit, I had to add some freon to get it to start, but I was not using recommended superheat and subcooling to determine how much freon to add, rather I was shooting for the recommended suction and discharge pressures (because at the time I did not know a whole lot about superheat and subcooling). But with the freon a little low, my superheat was greater than 20 degrees (factory recommends 10-18). Thus, at start up after a long time idle, freon at the evaporator (start of water jacket for heat mode) was going below 32 degrees temperature for long enough (four minutes) to trigger freeze safety shut off. (Unfortunately I was not seeing this code set because I was shutting off the power and all I ever saw was a blinking LED, and I was ignoring FP1 because I thought it was a measurement of water temperature, however it is a freon measurement.) This FP1 sensor temperature gradually came up to a decent temperature during operation (40 degrees); however, when idle for longer than 20 hours FP1 took too long to come up to temperature so the unit would shut off after it sat unused.

11-11-16, 12:21 PM	#1
Fathompin Lurking Renovator Join Date: Nov 2015 Location: Dayton Ohio Posts: 12 Thanks: 1 Thanked 1 Time in 1 Post	Compressor shuts off within 5 minutes with cold start up, then runs fine? Hi there. What would I look for to fix a geothermal compressor that shuts off within 5 minutes of initial start up from cold, every time, then after a 10 minute wait will start up and run fine for hours. High Pressure and Loss Of Coolant signals are good going to control board, nothing much else going into control board. I suspect the compressor's own thermal shutoff, if so what is a course of action? Compressor discharge temp stays around 195 F. This is a new old stock system that is 8 years old and just getting used for the first time. Thanks.

11-11-16, 12:50 PM	#2
stevehull Steve Hull Join Date: Dec 2012 Location: hilly, tree covered Arcadia, OK USA Posts: 826 Thanks: 241 Thanked 165 Times in 123 Posts	Bad start capacitor? Easy to check it. I have seen similar odd things happen and replacing the capacitor worked. Let us know. Steve __________________ consulting on geothermal heating/cooling & rational energy use since 1990

11-30-16, 06:28 AM	#3
Fathompin Lurking Renovator Join Date: Nov 2015 Location: Dayton Ohio Posts: 12 Thanks: 1 Thanked 1 Time in 1 Post	Resolution I learned quite a bit from this experience. Here is the resolution: A little low on freon triggering FP1 (freeze protection). When I first received the unit, I had to add some freon to get it to start, but I was not using recommended superheat and subcooling to determine how much freon to add, rather I was shooting for the recommended suction and discharge pressures (because at the time I did not know a whole lot about superheat and subcooling). But with the freon a little low, my superheat was greater than 20 degrees (factory recommends 10-18). Thus, at start up after a long time idle, freon at the evaporator (start of water jacket for heat mode) was going below 32 degrees temperature for long enough (four minutes) to trigger freeze safety shut off. (Unfortunately I was not seeing this code set because I was shutting off the power and all I ever saw was a blinking LED, and I was ignoring FP1 because I thought it was a measurement of water temperature, however it is a freon measurement.) This FP1 sensor temperature gradually came up to a decent temperature during operation (40 degrees); however, when idle for longer than 20 hours FP1 took too long to come up to temperature so the unit would shut off after it sat unused.