Miller Package Unit A/C stopped working.

Questions about repairs and parts for Nordyne furnaces, air conditioners and heat pumps for manufactured homes including Intertherm, Mac and Miller brands. Click here for Nordyne parts.

Moderators: Greg, Mark

Posts: 48
Joined: Mon May 31, 2010 12:32 pm

Wed Aug 31, 2011 7:55 pm

Not certain of the model number, but certain about the serial number:

Model: MSC-3GE-C2 (am fairly certain of all characters but the "E" - could be an "F").
Serial: MK0387-01039 (certain of this number).

Miller Package Unit A/C (that's what's on top of the cabinet: "Miller") - could only make out Division of Lear Siegler, Holland, Michigan. This mobile home park was built in late 50's. This unit could be quite old. There is a readable date of Mar. '87 - have no idea what else it says on that line of data plate, before or after that date. Electrical diagram was no help - unreadable ( what was left ot it).

This unit stopped working, not sure if the blower was still running or not when compressor and condenser fan stopped. There is 240vac at the outside disconnect next to the package unit cabinet, and when I push contactor in, compressor hums/groans, but no start. Cond. fan does nothing. Didn't check power at contactor yet (primary or secondary). When I heard the compressor groaning, I just assumed there was 240vac getting to it - should've checked - will tomorrow.

There are three capacitors. Two smaller ones are both 7.5uf/370vac. The third one (Dual Run cap only being used on the HERM side) has no markings on it anymore. Its size is 5" tall, 3-1/2" wide, about 1-7/8" thick (as mounted/positioned on the electrical compartment vertical wall, with terminals on top).

The Dual Run capacitor is only being used on the HERM side, which I know is for the compressor. It measured (common to HERM) 37.2uF . If the tolerance range 5% (is that correct, 5% ?), and this is a 40uF capacitor, then 40-5%=38uF. It measures just under at 37.2uF. Would that be enough to make it not start that compressor? Or could this be a 35uF capacitor and it's just a bit stronger than its rating, or is that a bit too high of a measurement (37.2uF?) for a 35uF capacitor?

Would it hurt anything if it were supposed to be 35uF and I put in a 40uF?

The capacitor that goes to the cond. FAN is a 7.5/370v, but measures 6.85uF. 7.5uF less 5%=7.13uF. As in above, that's enough to not run the FAN? ( this FAN is not locked up, nor is it running).

Not that it matters as far as the cond. fan and compressor not running, but...The other 7.5uF capacitor for the blower measures 7.6uF Never did check for air from the vents yet (don't remember hearing anything though from that side of the A/C cabinet though (I'll check it out the morning).

None of them are dome-shaped at all, on top or bottom, nor leaking.

Posts: 100
Joined: Mon Mar 07, 2011 9:32 pm

Thu Sep 01, 2011 6:51 pm

The run capacitors are close enough in the range that you have measured. The 5% gain or loss is the standard but I know that they can be as much as 10% and be just fine. Not the best idea but still works. I wish i could help more but i dont know alot about the packaged units.
Please remember to check and change your filters.

Posts: 48
Joined: Mon May 31, 2010 12:32 pm

Thu Sep 01, 2011 7:57 pm

Went back today and watched exactly what was happening (which I should have done yesterday). Package unit would run for 5 or 10 minutes, then condenser fan would come to a halt. Its motor would hum loudly and compressor stopped running.

First I changed all three capacitors, but no help, same thing happened. Installed new cond. fan motor - no more shutdown. Cond. fan ran without stopping, but compressor wouldn't run till I put the new capacitor back in (for compressor - I had taken them back out after I realized the caps weren't the problem - it was a bad cond. fan motor).

Okay, so new cond. fan motor and new capacitor (40uF/440 vac - they didn't have a 370vac model) put it back in the pink. Plenty of condensation on the suction line after a 15 minutes and the line was cold. Amps draw on one leg of compressor was only 12 amps (maybe that's ok?) and 5 amps on the other leg, but the house cooled down to "comfortable pretty quick, which me thinks was pretty good considering the heat here today (also it was in the hottest part of the day, when the home was really hot inside).

Thx for your reply Bill.

A while back, I heard Robert was ill. Is he ok now?