Johnson Controls A421ABC-02C A421 Series Electronic Temperature Control, -40 to 212 Degree F Temperature Range, Single-Pole, Double-Throw

I've been using these for 8 years in an application where they switch constantly day and night. Combined with RIB relays to isolate the loads from the controllers, these have been flawless. These do exactly what they should do year after year. These harken back to a time when things were built to last and do the job they are supposed to do. It's a shame so many products fail to produce the bare minimum. I have 4 of these (actually the other 3 are pre Penn and one is pre 421 designation) running in various tasks in my house and will always go to Johnson Control (now Penn) for this application assuming they continue to build a quality product.

I have 2 A419 and 1 A421. I have used them at times control a fish smoker a heating pad for seedling starting and to control the blower on a gas heater. The A419 works best for some applications as it has a differential setting that follows a set point that has to be changed often as in smoking fish and I only have to make 1 adjustment each time. The A 421 works good for a set point that remains fairly constant as in a blower control for a heater. In using both the A419 and A421 I have a contactor for the final switching heaters for smoking. It seems the sensors are interchangeable which is a nice feature as I has one fail "sF" while smoking fish so I had a spare from one of the other ones not in use.

This is a boring product, as it should be. Once I deciphered the instructions and got it wired up and configured, it's worked without any fuss. The menu system isn't the most obvious, but once you figure it out, it's acceptable.Our fridge went out and I used this to convert a wine/beer fridge which only went down to 40F.I chose this over other cheaper ones because it has an anti-short cycle mode which is important for refrigeration to keep from damaging the compressor.

Bought 2 in February this year for 2 keezers, identical settings, one works the other does not. even though the screen works, it does not powers up the device even when the light indicator indicates power on. contact the seller said the guarantee expired suggested to contact manufacturer, I ask them to provide the manufacturer's contact did not got a answer back.still looking for the manufacturer. will go for with another brand most probably.Seller/Manufacturer if you read this please provide me with a email to help me solve my issue.UPDATE: wrote the manufacturer, no answer from them.

This is my second controler. The first is being used to repurpose a freezer into a refrigerator. It works great, and I can still use it as a freezer just by tweaking the dial. The second unit is on a cheap upright fridge that has a temperamental temperature control unit. As purchased, the fridge had a very wide set range, which resulted in wide variations of compartment temperature. With this controler I can set the high/low range to exactly what I want. Instructions are a bit confusing, but not impossible to figure out. The thing to remember is this controller can do much more than what is needed by the average homeowner. Don't get caught up with the setting options. This unit is highly recommended as an easy fix for a wonky cooling unit, or beer fridge, or.....

I haven't had this A421 controller for long but it was easy to set up and works as it should. I am using it to turn heat tape on and off at my RV trailer. I wanted something that is rock reliable even if costing many times more than those cheap plugs that have some sort of thermostat inside. Seems like those cheapies would be prone to burning up and don't I need a fire hazard or frozen water lines.There are fancier versions of this controller which have more options. I believe you can do temperature corrections on this but the option I do remember is being able to delay startup up to 12min from the last off-cycle. This would be to prevent quick-cycling of the controller such as if your on and off points are too close.I paired this with the Easy Heat cut-to-length cable. At least the cable I got is fairly low wattage per foot and that is what I wanted.The cord is pretty long but that could be helpful in many cases to install the controller in a good access location.

I'm on my third one of these controllers for my chest fridge, which will tell you something. However each replacement I order has been upgraded and improved and lasts longer than the previous one. This one has a great digital display. The coil is a nice thick rubber? or plastic? of some sort. Sturdy.Very easy to use, even with no knowledge of electronics. Keeps my chest fridge temperature accurately within my chosen range.The simplicity, affordability, and extremely low energy use of the whole system (temperature regulator plus chest freezer) even convinced my husband that our next fridge will also be a chest fridge.

The new A421 is a solid improvement over the A419. There is now a on and off set point, as well as an always on back-light. I welcome these changes. For people familiar with the layout and use of the A419, this will work well. I'm using this to revive an older bar fridge that had a analog controller that was no longer working. Since the fridge is nice, this saved it from the dump.This did come with the power cord pre-installed and ready to go. Quick shipping from the beverage factory.

I bought this controller to replace an Inkbird controller that was very unreliable. This controller works perfectly. Some people might find the DIY wire-up a bit off-putting but I didn't mind at all. The unit comes with the controller and probe only. There is no power cord, there is no output cord, you need to wire it up custom to your application. I'm glad I found this controller to replace that terrible Inkbird and I will buy another one in a minute the next time I need a temperature controller.

Bought this to replace a A419 that the relay was sticking on and causing the cooler to freeze... Directly replaced the A419 with this A421 without having to make any changes to wiring or mounting. Setup was easier than the A419 (I didn't turn on Advanced Mode) as one only needs to set relay on and off temperatures, minimum time between cycles, and failure relay mode. Instructions included are very thorough and walk you through more advanced stuff (Not needed in my case...). Another well built product by Johnson Controls and I will buy again in the event another one of our older controllers has an issue.

Check the voltage required- works well for my solar wall but because I ordered the wrong one (not realizing that there were different ones under the same replacement model) the project was delayed. It works great once I got the one I needed.

The package arrived within a day. I used a 12 ft extension cord (14/2) as my wire and plugs. I as using this with a chest freezer purchased from Costco as a refrigerator at our off-grid remote access cabin. I needed to change the settings on my inverter from search mode to always on. The programming was simple and I was up and running within 5 minutes. I zip tied the temperature probe to one of the wire baskets in the center of the freezer. Everything worked as described!

The item was delivered in a good conditionA license tech tried to install and it did not workHe brought another from his truck ... same model... worked goodSo something looks wrong inside the controller