The condensate pump for my HVAC systems gave out a couple of months ago. I went down to the basement and stepped in a puddle. It’s amazing how much water came from the HVAC system in just a day. I’ve never really liked this particular pump. It’s noisy and it has failed before – I’ve taken it apart to figure out what was wrong only to have it work again. It has a lever on the side where you can push down to manually activate the pump – to override the float sensor and I’ve needed to do that before. So as I sloshed through the puddle to the pump this time, I was surprised to find that the manual lever did nothing and that the power to the outlet was still on. I didn’t need much convincing to buy a new one. I got a new DiversiTech LCV-120 which has no mechanical float and is incredibly quiet. I really should have replaced the Little Giant with the DiversiTech at the first sign of problems years ago.
However, I don’t want to be without a condensate pump even for a little while so having a backup would be useful. And I’m considering making some sort of system where the DiversiTech is somewhat raised up and I have a second pump below it with some sort of battery back up to make sure there is never a problem again. And therefore, I set out to repair this thing – the pump that I hate, the Little Giant VCMX-20UL.
Apologies for only having a few pictures – I didn’t set out to make this a blog-worthy repair. In fact I didn’t have high hopes of success. But when things went well, I realized that writing this up could be useful to others. As always, I’m not an expert and this is not professional advice. Repairs are at your own risk. You may get electrocuted, kill yourself or others, start a fire, burn your house down, etc. – it’s all on you.
The first step is to unplug the pump and dry everything out. This repair is not one that can be done instantly. If you have a failed Little Giant pump that won’t respond to the manual lever, this repair isn’t going to help right away – you are going to need to clean up the water with another pump or shut down your HVAC for a week or 2 – or get a new pump and use the Little Giant as a backup like I am going to do. To help dry things out, remove the top blue motor assembly from the bottom black tray by pushing at one end and hinging at the other end. Empty the tray and leave the motor assembly upside down for a few days to dry.
Once everything is dry, plug the pump back in and check to see if the pump will work now by pushing on the manual lever. If it will, it’s in the state that mine had been for a few years and likely to fail at some random point. You may want to continue with this repair or just put the pump aside and consider a repair in the future.
With the pump unplugged again, unscrew the power cable clamp from the cover by undoing the 4 screws that hold it in place. Then unscrew the motor from the top lid. There are 4 screws that hold it in place and then a sort of plastic finger that needs to be pushed to unlatch it. At this point, the blue cover should now be completely separate from the motor and you’ll see something similar to the picture below.
The part that failed for me is that silver thing near the motor winding. You can test for failure using a continuity tester or a resistance setting on a DMM. It’s a sensor to cut off electricity flow at a certain temperature but mine was now permanently cut off. And this thing could have been intermittently working before which is why it the pump had temporarily failed before. I thought about just twisting the device to short out the leads and make the device irrelevant but decided it was probably there to avoid some sort of thermal overload and it would not be safe to use without it. Also, as I was bending it to try to see what it was, the thin wire snapped off the connector attached to the black wire – the infeed AC.
As you can see in the picture, it is a “CD79F” and Googling that led me to eBay where I bought a new one for $3.99 including shipping. I’ve been finding that some eBay listings that say they ship from the US are actually shipping from other countries to a place in the US and then reshipping from that US location. So it took a while for the part to arrive – it was about two weeks. Again, keep that in mind if you are doing this repair for a device you want to get back into service right away. If you are looking for the part elsewhere, it is a “Cantherm Thermal Protection Cut-out”.
The next step is to solder the new one in place and this part was hard for me. The new one comes with really nice long leads on it that I clipped shorter to mimic the lengths of the original one and so I could solder it in place to the motor winding wire and to the infeed AC clip. But soldering it was brutal because the solder did not want to stick to the clip. The original attachment was not soldered – it was just done with a friction fit of the thin little wire on the original. I had to sand down the clip to remove some finish, add flux, and even then, there’s not good solder point. And soldering the other end to the winding wire turned out to be equally challenging since the winding wire is tough to heat up and has a funny finish on it that I had a hard time removing.
Once the new one was in place, it looked like the first picture above. Because that first picture above is actually after the new thermal protection device is in place. I have no picture of what it looked like before the repair, sorry. And note that I used electrical tape to help wrangle the device and wires into place so they weren’t bouncing around under the cover. The original being a solid single strand on the thermal protection didn’t need to be wrangled but it still looks like it should have had a bit of insulation to prevent shorting out against the neutral conductor clip.
After I had the soldering finished and before I put it back into the case, I plugged it in to test. (Keeping in mind that now there are exposed points where you can get zapped if you touch.) Nothing. Still dead. I unplugged again and checked connections and confirmed everything was working, except for the switch of course. But wait, the switch didn’t even have a path through when the switch was triggered. Ah-ha, so this may have been the actual original failure point. So back to eBay to look for the switch part.
There’s a plastic finger on the bottom holding the switch mount in place – release that and push up and the switch unit just slides off of the mount. It’s hard to see in the picture, but the switch is a 83133169 made by Crouzet. I found one listed on eBay for over $50. What? For this silly little thing? I looked elsewhere and found that Mouser had one listed for a similar cost and they didn’t even stock it any more. There were others that might have been acceptable substitutes but they might not have and I was pretty well fed up with the thing by this point.
I removed the wires from the switch by pulling the connectors. I decided to try contact cleaner spray from the outside of the switch. A longshot, I know, since the contacts might have been well away from the switch entry point. When that dried and there was no improvement, I figured everything was trash at this point so it was time to take apart the switch and see what happened – it wouldn’t matter if I couldn’t get it back together again. I got lucky here – the switch actually nicely came apart without anything needing to be broken. There was no glue holding it together. Just pulled the two sides apart and the metal switch lever fell out and the body opened.
And here it was easy to see the problem. The switch was not making contact on both sides. It’s a weird sort of switch design and it isn’t that surprising that it is no longer available. Presumably, these things either weren’t meant to last or they were dodgy from the start. The switch plunger in the middle is supposed to snap through a copper bendy thing which is supposed to then bridge the two stationary contact points. But in mine, it was easy to see that one side was bending up while the other side was not moving. And it didn’t appear to be from a blockage – just like the copper bendy thing wasn’t bending the right way – like a spring that had lost its sproing. I blasted the whole thing with contact cleaner and cleaned everything down with a paper towel. The contact points ended up a silvery finish. And I bent the copper bendy thing so that it would snap into place correctly when the switch was pushed. It went back together as easily as it came apart and I confirmed that the switch did now show low resistance on the DMM when I switched it on.
After putting the switch back in place and reconnecting the wires, I again tested it (carefully) to see if it would turn on. It did! I reassembled everything and tested the manual lever and it works perfectly. The full cost of the repair was the $4.99 for the replacement thermal cut-out. But I spent lots and lots of time doing the research and the repair. So my time would definitely have been better spent elsewhere and I could have just bought a second DiversiTech pump to have on hand. But I feel better throwing less stuff away, I learned from this repair, and now maybe it can help others too. Let me know if you tried this repair and how it goes for you.