Just purchased a DR D-2-A16

Jun 6, 2019 13:21:13 GMT pumpman said:

I recently went to an auction across the street from my house. On impulse I bought a DR D2-A16 (#1588456) for $25. The cabinet is in good condition however I think the good news ends there.

I plugged it in for just a few second and hear a faint condenser hum. The overload heater glowed orange and the main contacts either opened or closed. I quickly unplugged it.

I should point out that while I'm mechanically adept I have no helpful knowledge about refrigeration and very limited knowledge about electricity.

Run to Start 7.6
Run to Heater 0
Run to Common/Heater 3.6
Start to Heater 0
Start to Common/Heater 4.5
Heater to Common/Heater 0

Run to Ground 0
Start to Ground 0
Common to Ground 0

There was no continuity between the heater leads.

I assume this is all bad news but would appreciate your input. Thanks.

Hi, and welcome!

I wouldn't assume it's too horrible until digging in a little further!  It seems, based on those readings, that your winding is OK. The overload heater glowing and tripping off is indicative of something like this;  Either, the start circuit did not complete - or the compressor is stuck. Both of these possibilities are recoverable in most instances.

The heater being open-circuit is sort of "to be expected" as they say. There are several members here who have purchased extra heaters during a group buy, and may be willing to let go of one. If the machine was run extensively without a functional heater, it's entirely possible that the compressor became stuck due to refrigerant liquid trapped in the lubricating oil. This will often remedy its self once a new heater is installed and the compressor is given a healthy jolt of power to get it moving the first time.

There is a resistor in the start circuit, as well as the start-relay contacts.  If this resistor is bad, or the contacts are dirty; it can prevent the compressor from starting.

Hope this gives you some things to look at!

Sincerely,

David

Jun 6, 2019 23:40:33 GMT pumpman said:

Thanks Dave. That gives me a starting point for the process of elimination.

Does anyone out there have a heater they would be willing to sell?

That makes me think of another question. When I pulled the heater out, the insulation on the wires leading to the heater completely crumbled off, leaving bare wires. Do I tape the new wires to the bare wires and then pull the opposite ends in the control box to fish them through?

Thanks everyone! I’m always amazed at people who are so willing to share their knowledge and expertise to help a stranger.

Yeah, often the wiring does crumble on these, pretty badly. Seems the cloth covered wire on the earlier DR's holds up better than the rubber on the later models; but none are completely immune to the effect of heat and time.

The worry is disturbing the wiring to the compressor by pulling the new wiring through. It's nearly impossible to rewire a DR without having to disconnect lines, or risk breaking lines. It's best to be very careful no to disturb the compressor wiring while doing the heater replacement. On my D2 the original heater wires were bad, but I was able to cut off a little of them and connect the heater to the original wiring. It wasn't completely shot so there was that option. If you need top pull through new heater wiring, just be mindful.

I have a few extra heaters, but I won't have access to them for an undetermined time; which could be months. There are several heater posts here where others have ordered them online as well. They are not hard to get. You can get one for $50 or so, quickly and effortlessly. Getting one for less takes more time and networking.

Sincerely,

David

Jun 10, 2019 3:37:21 GMT pumpman said:

I did read that thread. Like I said earlier I have very limited electrical knowledge. Most of that thread was over my head.

Was the 200 setting I used in on the ohmmeter, the correct setting to use? Do you think the reading is actually 3.27 and not 32.7? If so then the resistor is perhaps the 3.4 Ohm resistor. Would the 3.4 work if the manual says it uses a 6 ohm?

Hey, any knowledge combined with the desire to learn more is a huge step in the right direction!

As for the meter, yes the 200Ω setting is correct. The meter should place a decimal point in the display at the correct position. If you select the 200Ω range, it should measure 3.27 and 32.7 correctly.

I am pretty certain the compressor motor would start if given a 3.4Ω instead of a 6. The problem would likely be that the start-relay would not transition from start to run mode, due to the excess current drawn by the motor due to the less resistance.

Sincerely,

David

Jun 10, 2019 14:47:01 GMT pumpman said:

Dave, if it did not transition from start to run mode, would it cause the symptoms I originally described?

Faint condenser hum
Overload heater glowed orange
The main contacts either opened or closed"

Dave you refer to a "Start Relay". Are you referring to what the diagram calls a "Starting Relay Shunt Coil"?

Is there a delay in time that the start-relay transitions from start to run mode or is it almost instantaneously?

Is there a way for me to heat the sump to drive the refrigerant out of the oil? I prefer to not buy a heater until I'm sure this patient is going to live.

Hi, sorry I am late in replying!

If the start relay did not transition from start to run and the compressor started the result would be a gradual overheating of the overload heater. The compressor would have sounded as if it was running and it would have gone for a minute or more before the overload tripped.

If the compressor is stuck (or the start circuit is not working) the overload will heat up much faster.

The transition from start to run mode should take about 1/4 to 1/2 second. Here is a video with one in operation. I know yours is a D2 so it will be somewhat different. But the timing should be similar. youtu.be/ERdcjIUvN_I?t=568

I have used a 50W soldering iron before, inserted into the heater well. That was adequate!

You can build more torque in the motor for starting; by replacing the resistor with a capacitor for a boost function. That may get her going!