I got a call from a tech in another office today for help regarding a WIF that has had multiple compressor failures. I don’t have a lot of data and I’ve never been to the site so bear with me.
The system... WIF with 2 evaps piped to one CU that sits on the roof 8 feet above the top of the box. The LLSV is located in the CU. The suction line has an oil trap at the evap outlet and an inverted one on the roof. I do not know how big the box is, evap/CU/TXV model numbers or even the voltage/phase. The LPC is set to cut-in at 30 psi with only an 8psi diff.
The back story... customer is a well known southern style restaurant. We picked up the account sometime in the last few months. Apparently the the previous service company wasn’t doing a good enough job with the refrigeration work, though they still do the HVAC work. The GM tells our tech that this particular WIF has had 6 compressors in the last 10 years. The unit went down the other day, our tech goes out and finds the pressures equalized while the compressor is running (scroll ZF18K4E). I do not know what the pressures were nor the amperage. He condemns the pump and orders a new one.
He installed the new pump yesterday, actually an entire CU. I don’t know the model number but the tech is saying the compressors were the same. Box was empty and at room temp when he started it up. He said he watched it drop to about 50 degrees and left. That kind of pissed me off and I told him never leave a new system or compressor that you just started up until it cycles a few times. He said he was just too tired which I’m sure he was, I looked up his hours and by the time he got home Wednesday night he had accrued 49 hrs. That’s an entirely different issue that I need to address. But anyway he came back this morning to check on it and the box was at room temp. Puts his gauges on it and the pressures are 90/150 and the pump sounds BAD. The compressor was drawing 7 amps.
Now this guy that’s calling me is pretty good at refrigeration. He’s the lead tech in his office and is very meticulous in his work. That said he explained to me that he had a vacuum pump issue yesterday. During the second evacuation (he always flushes with RX11 and preforms a triple evac) his pump was making an odd noise and the evac time took longer than expected. He said by the third evacuation it had gotten worse and he only let it get down to 600 microns before he called it good and charged it up.
Now he’s trying to say the second pump failure is due to the poor evac. I’m very skeptical of that. Possibly there was some nitro left over or maybe some RX11 flush (less likely) that came back and damaged the pump. But I think that after a triple evac and getting it down to 600 microns on a new CU there’s not going to be enough moisture/non condensibles/nitro/RX11 to make the pump fail in 12 hours.
My thought is that each compressor met their end the same way, an oil slug. With the LPC set to open at 22 psi isn’t it very possible that the evaps became somewhat oil logged, especially with the multiple compressors? Does the location of the LLSV matter? Say it came out of a defrost or off cycle and immediately brought back a hunk of cold oil, would that be enough to damage the compressor to the point of equalizing the pressures.
And speaking of that, I’ve seen damaged valves on recips many many times but do scroll compressors have failures that cause equalized pressures?
The system... WIF with 2 evaps piped to one CU that sits on the roof 8 feet above the top of the box. The LLSV is located in the CU. The suction line has an oil trap at the evap outlet and an inverted one on the roof. I do not know how big the box is, evap/CU/TXV model numbers or even the voltage/phase. The LPC is set to cut-in at 30 psi with only an 8psi diff.
The back story... customer is a well known southern style restaurant. We picked up the account sometime in the last few months. Apparently the the previous service company wasn’t doing a good enough job with the refrigeration work, though they still do the HVAC work. The GM tells our tech that this particular WIF has had 6 compressors in the last 10 years. The unit went down the other day, our tech goes out and finds the pressures equalized while the compressor is running (scroll ZF18K4E). I do not know what the pressures were nor the amperage. He condemns the pump and orders a new one.
He installed the new pump yesterday, actually an entire CU. I don’t know the model number but the tech is saying the compressors were the same. Box was empty and at room temp when he started it up. He said he watched it drop to about 50 degrees and left. That kind of pissed me off and I told him never leave a new system or compressor that you just started up until it cycles a few times. He said he was just too tired which I’m sure he was, I looked up his hours and by the time he got home Wednesday night he had accrued 49 hrs. That’s an entirely different issue that I need to address. But anyway he came back this morning to check on it and the box was at room temp. Puts his gauges on it and the pressures are 90/150 and the pump sounds BAD. The compressor was drawing 7 amps.
Now this guy that’s calling me is pretty good at refrigeration. He’s the lead tech in his office and is very meticulous in his work. That said he explained to me that he had a vacuum pump issue yesterday. During the second evacuation (he always flushes with RX11 and preforms a triple evac) his pump was making an odd noise and the evac time took longer than expected. He said by the third evacuation it had gotten worse and he only let it get down to 600 microns before he called it good and charged it up.
Now he’s trying to say the second pump failure is due to the poor evac. I’m very skeptical of that. Possibly there was some nitro left over or maybe some RX11 flush (less likely) that came back and damaged the pump. But I think that after a triple evac and getting it down to 600 microns on a new CU there’s not going to be enough moisture/non condensibles/nitro/RX11 to make the pump fail in 12 hours.
My thought is that each compressor met their end the same way, an oil slug. With the LPC set to open at 22 psi isn’t it very possible that the evaps became somewhat oil logged, especially with the multiple compressors? Does the location of the LLSV matter? Say it came out of a defrost or off cycle and immediately brought back a hunk of cold oil, would that be enough to damage the compressor to the point of equalizing the pressures.
And speaking of that, I’ve seen damaged valves on recips many many times but do scroll compressors have failures that cause equalized pressures?
