ECU/Genset identification and troubleshooting

I have just acquired a ECU/Genset trailer. The NSN it was sold under is 8340-01-459-4352 but there are no legible ID tags to be found on the machine itself, so that is subject to govplanet's accuracy level. It is powered by a Lister Petter engine and mounted on a hmmwv era trailer. I believe we saw a 1999 mfg date somewhere, but I can't find it again now.

The genset seems to be operating correctly. The ECU was said to be 'drained' of refrigerant. The power light illuminates but it will not run the fans or compressor or heater. We have opened the control box and found the magnetic starters. If you push each of the starters in manually, the appropriate component runs. At this point we stopped to attempt to find necessary documentation or advice. I returned and started to trace the control wires to the mag starters in the control box, and they appear to go to a circular 8 pin socket labeled PSR which appears to have a component missing.

pics attached

After discovering Poccur's incredible knowledge in this area I searched his past posts and between them and googling I am gathering that the missing component "PSR" is possibly 'phase shift register' and could be the phase monitor which he said locks out control power in the event that input power is out of phase. If that is correct, I need to find out where to get one.

I wonder if the last time it was used it was used as a genset and someone pulled this component out to prevent Joe Blow from messing with the HVAC part.

And based on information from a friend who is a technician in the military, it appears to be a 20kw generator and 8 ton AC.

I would just jump that component and see what happens. Of course the first time it runs, make sure it is grounded well and use a stick to turn things on. Then use a meter to ground to see if there is any stray voltage. I don’t understand why they are worried about phase when if comes off a generator 3’ away, not some sketchy commercial power in a third world country. Also make sure any fans are turning the correct way.

I have recently run one of my FDECU-5 units powered by a MEP 804b over three hundred hours to cool my house as I worked through some cooling issues. I looked at the schematic on the unit and it did not list anything having to do with phase. These units have a world of capacitors (around 6) and are 5 ton and need 60 amps, 208v. I did not see any caps in your pictures. Mine does have at least 3 mag starters. It is a pain that they sometimes remove the refrigerant when they turn in A/C units, I bought a never put in service unit just as it left the factory except some numnuts drained the R-134a (so dangerous, it is in most vehicles on the road!!!). If that unit needs R-22, get it quick since it is illegal starting in 2020. Did you try Liberated manuals using the NSN for a book?

Robert Sears

I would just jump that component and see what happens. Of course the first time it runs, make sure it is grounded well and use a stick to turn things on. Then use a meter to ground to see if there is any stray voltage. I don’t understand why they are worried about phase when if comes off a generator 3’ away, not some sketchy commercial power in a third world country. Also make sure any fans are turning the correct way.

I have recently run one of my FDECU-5 units powered by a MEP 804b over three hundred hours to cool my house as I worked through some cooling issues. I looked at the schematic on the unit and it did not list anything having to do with phase. These units have a world of capacitors (around 6) and are 5 ton and need 60 amps, 208v. I did not see any caps in your pictures. Mine does have at least 3 mag starters. It is a pain that they sometimes remove the refrigerant when they turn in A/C units, I bought a never put in service unit just as it left the factory except some numnuts drained the R-134a (so dangerous, it is in most vehicles on the road!!!). If that unit needs R-22, get it quick since it is illegal starting in 2020. Did you try Liberated manuals using the NSN for a book?

I put that NSN in search and it seems to match a DRASH HP-4/188. It shows a 8 ton/18kw combo.

Robert Sears

Found out how the phase monitor works and jumped it. Everything works. Gonna get charged tomorrow. It is 409 or 407 or something like that...have the bottle to go in it.

I would guess that the phaze monitor is mostly for when it is hooked to shore power.

robertsears1 said:

I would just jump that component and see what happens. Of course the first time it runs, make sure it is grounded well and use a stick to turn things on. Then use a meter to ground to see if there is any stray voltage. I don’t understand why they are worried about phase when if comes off a generator 3’ away, not some sketchy commercial power in a third world country. Also make sure any fans are turning the correct way.

I have recently run one of my FDECU-5 units powered by a MEP 804b over three hundred hours to cool my house as I worked through some cooling issues. I looked at the schematic on the unit and it did not list anything having to do with phase. These units have a world of capacitors (around 6) and are 5 ton and need 60 amps, 208v. I did not see any caps in your pictures. Mine does have at least 3 mag starters. It is a pain that they sometimes remove the refrigerant when they turn in A/C units, I bought a never put in service unit just as it left the factory except some numnuts drained the R-134a (so dangerous, it is in most vehicles on the road!!!). If that unit needs R-22, get it quick since it is illegal starting in 2020. Did you try Liberated manuals using the NSN for a book?

I put that NSN in search and it seems to match a DRASH HP-4/188. It shows a 8 ton/18kw combo.

Robert Sears

Click to expand...

Robert,

Often these things are powered by sketchy third world power sources. Or the US gov. rents some over priced, third world power source, and when the phases don't match, it often causes problems. I personally pumped several hundred gallons of glycol out on to the ground, because of phase incapability. I watched 4 electric roll doors destroy themselves for the same reason. Most air con's, and the FDECU-5 is one of them, will not operate if the phasing is not right. The relay is off the shelf, if I remember right. Should not be hard to find.

robertsears1 said:

I would just jump that component and see what happens. Of course the first time it runs, make sure it is grounded well and use a stick to turn things on. Then use a meter to ground to see if there is any stray voltage. I don’t understand why they are worried about phase when if comes off a generator 3’ away, not some sketchy commercial power in a third world country. Also make sure any fans are turning the correct way.

I have recently run one of my FDECU-5 units powered by a MEP 804b over three hundred hours to cool my house as I worked through some cooling issues. I looked at the schematic on the unit and it did not list anything having to do with phase. These units have a world of capacitors (around 6) and are 5 ton and need 60 amps, 208v. I did not see any caps in your pictures. Mine does have at least 3 mag starters. It is a pain that they sometimes remove the refrigerant when they turn in A/C units, I bought a never put in service unit just as it left the factory except some numnuts drained the R-134a (so dangerous, it is in most vehicles on the road!!!). If that unit needs R-22, get it quick since it is illegal starting in 2020. Did you try Liberated manuals using the NSN for a book?

I put that NSN in search and it seems to match a DRASH HP-4/188. It shows a 8 ton/18kw combo.

Robert Sears

Click to expand...

Robert,

Often these things are powered by sketchy third world power sources. Or the US gov. rents some over priced, third world power source, and when the phases don't match, it often causes problems. I personally pumped several hundred gallons of glycol out on to the ground, because of phase incapability. I watched 4 electric roll doors destroy themselves for the same reason. Most air con's, and the FDECU-5 is one of them, will not operate if the phasing is not right. The relay is off the shelf, if I remember right. Should not be hard to find.