CPS 5-2-1 CSRU1 Compressor Saver for 1 to 3 Ton Units

My a/c unit is getting old. The compressor is weak and beginning to drag on start-up, drawing more amps than the breakers can handle. All last year, house lights would dim when the compressor kicked on and by the end of summer last year the circuit breakers began to trip at start-up. I called my HVAC guy and he came out and put on a small 2 wire hard start kit which cost $100 for the kit and $75 dollars for installation. It got my a/c working again , but by mid winter my heat pump quit working and we were forced to heat the house with the back-up electric heat strips in the furnace. Needless to say our electric bill was twice what it would have been had the compressor worked for the heat pump but we were in the middle of winter and there was no way we could afford a new system. This year I called around to get estimates on a new a/c unit and after recovering from the shock of what it was going to cost, I decided to try one more attempt to get my compressor starting again. I pulled off the $175 hard start kit only to discover it was burned to a crisp. When I installed the new 521 hard start kit, my compressor fired right up... no lights dimmed ... no breakers tripped, and it's been running perfect for almost three months now. This is a great product, very heavy duty with great build quality and cost a fraction of what I paid a "Professional" last year. I ordered it from Amazon and installed it myself. Installation was super easy. Instructions were good, but for additional reassurance, I watched a couple of videos. A/c compressors don't last forever and eventually they will have to be replaced. If your unit hasn't locked up yet , these 521's may be a life-saver and buy you some time. They could maybe even fix the problem all together until it becomes someone else's problem further down the road. WELL worth the money and I will buy again if needed.

Works great on my trane x12. It literally saved me at least $10,000. Hvac servicemen told me to replace the locked compressor with a new unit. Due too having to use a new type freon because of global warming it would have to be a new furnace also. So they tell you you can't fix it and you must spend 10k to replace it. Well fortunately with advice from a family member, a little you tube research and amazon this fixed the compressor start up. 5 minutes to plug in and mount. Took away hvac industry scam license to steal for now.

I installed this in a 2002 2.5 ton Trane heat pump that had not been exhibiting starting issues. At this age, I don't expect the heat pump to last much longer, but for the price it was cheap attempt to try prolong it's life. Install was reasonably straightforward. My contactor had been replaced previously, and the new one was installed upside-down. Even if it was installed per the wiring diagram on the unit, the compressor common would have been on T2 instead of T1 like the instructions call for. There was an envelope of documents attached to the box that had the wiring diagram; as always before doing any work I compared the diagram to what was actually in the unit, finding and tracing the compressor wires to determine the appropriate places to connect the 5-2-1. My only other installation complaint was that the screws provided were a little long (certainly longer than the stock screws holding the other components in my unit). My unit had holes pre-drilled and taped over, but I was concerned that if I used them the extra screw length would interfere with the coils. No huge deal here either, there was room at the very top of the wiring compartment to drill a couple new holes that were safely above the coils. Before installing the 5-2-1 kit I measured the inrush current on the compressor common wire, and got a value of 33.6A. I repeated the test after installing the kit and got 25.9A. In more subjective measures, the compressor startup time and sounds seem to be reduced; it just clicks on to the steady hum right away now, instead of seeming to take maybe a half-second to come up to speed. Overall, I would definitely recommend this kit (or the others from 5-2-1 as appropriate for your unit size). Just make sure to trace wires and compare with the diagram, instead of blindly following the instructions from the kit. I don't knock 5-2-1 for this; they're doing their best to support decades of equipment from a wide variety of manufacturers, and there's always going to be an oddball. Same with the provided screws; they'll probably work without issue for most people. Just use your head during installation, and check for clearance behind the mounting locations before doing any screwing or drilling.

This thing is truly nothing short of a miracle. We have a mini-split heat pump installed in a guest house and had been receiving complaints from the neighbor that the thing sounded like a wounded yak every time it started up. It was making an ungodly loud buzzing sound, BRRRRAAAAAAAANNNNNNZZZZZZ for about 15 seconds, then would give up and try again a minute or so later. it would do this 5 or 6 times before finally kicking in and even then, would sound sort of anemic. We had a tech out (from a company with hundreds of 5-star Yelp reviews), and they said that the refrigerant levels were OK, the capacitors were OK -- it was just old and in need of replacement. I did a little research and decided to try a hard-start kit before ponying up for a new AC and I'm so glad I did. I had to do a little reading to make sure I understood where the 5-2-1 Compressor Saver was supposed to be installed and discovered that I needed to splice a couple of wires to make it work, since I didn't have enough free posts on the top of the existing run capacitor, but even so, installation took only 10 minutes and the problem was solved! The AC now engages instantly and runs silently. I love it so much, I'm getting another for an LG ArtCool I have installed at another location. The 120 AC shares a circuit with outdoor lights and dims them every time the compressor kicks in; the literature that came with this unit says it will solve this problem too, so I'm anxious to give it a shot. Great product, 1/4 the cost of a service call, and easy to install and use. Shipping was fast and free with Prime. Seriously, this thing works so well and with so little effort, I have a hard time believing it! I keep asking the neighbor if all is well and looking for clouds of smoke on the roof, but after several days of very hot weather, it looks like a winner.

CPS is a high quality brand, will last very long, and easy to install. the only thing i changed: Instead of using the plastic mounting zip tie for the capacitor, i used a section of metal hanger strap- much safer and far more durable. Be sure to cut power to unit, and ground your existing capacitor terminals from Herm-Common and Fan-Common with a 5-10mohm resistor or at least a screwdriver before starting the work. $38 part saved me a $350 install from an hvac tech with a cheaper component. Stopped the lights from dimming on startup and starts up faster. was drawing 79A at startup, now 25A.

Seems to work as expected. Lowered start up draw by 20amps. Would be nice to see them include a mounting bracket for the capacitor.

This Hart Start Kit saves me a lot of money too. I called in an AC technician to check out my 10 year old unit as the compressor is getting noisy and was particularly loud when it starts up. Being in Arizona, the AC units get a lot of work out each year, so I wanted an experienced technician to check it out and have him take care of it. The technician found the unit was down 1/2 lb of refrigerant and that it was ok. To extend the life of the compressor until that this time he suggested installing a Hard Start Kit which would soften the kick-in phase of the units operation. That sounded like a good recommendation to me so I asked for a quote on what it would cost installed and to top off the refrigerant. I was shocked when he showed me the quote and I wasn't prepared to pay $653 (see attached photo of the quote) and if I really needed a new AC unit, I would do that at a later date. I his offer, thanked him and paid him for the service call. Not knowing what a "Hard Start Kit" was or what they might typically cost, I went to the internet right away to find out. To my surprise the cost was way lower that what I was shown and the installation so simple I just couldn't believe that service technician was quoting me $420 for the kit and installation. I found this on Amazon and the installation took less than 15 minutes (to include having to drill a hole for a mounting screw). And for this price and it's simple installation, I installed one on my second AC unit that is smaller and hasn't had any particular issues as yet. It took about 1/2 hr. to do both units including the time to get out my tools and put them back. It's been over a week now and the AC units sound much better when they start up . . . more like normal. And it may just be my perception, but both units seem to not only start up much quieter, they seem to keep running at a slightly quieter level. Taking sound measurements I was getting after installation was 72-74db, which is apparently normal for these units according to their speck sheets. Before installation, I was getting readings as high as 78-79 db. So, am so happy with this, I'm actively letting my friends and neighbors know and highly recommending this to them.

UPDATE: After seeing questions about the suitability of using this CSR-U1 on 120V compressors (like in my RV), I decided to check around... The general term for this type of start system is "potential relay" - turns out there are several potential relay replacements that are either 'universal' e.g. 110-270 VAC or adjustable for 120V capacitor start compressors. Supco makes a APR5 adjustable as well as a SUPR universal and ICM Controls makes UMSR-50 universal model. The Supco ones include a 1.0-1.5 second timeout so that if the motor doesn't start it won't continue to apply power - nice feature. I changed out my 5-2-1 relay to the Supco adjustable set to the recommended setting for 120V motors. 3 slide on terminals and one mounting screw - easy change! Look at my original comments below if you are changing from the typical RV AC 2-wire start-up circuit. I will leave one AC with the 5-2-1 and one with the Supco. Both continue to start and operate without issue :) One last thing: I always use a pair of pliers to (GENTLY) tighten the wire terminals before re-installing them - loose terminals mean issues later on! ORIGINAL: Replaced my 2-wire start device on my motorhome with this unit. My old start device was causing my breaker to trip when the ambient temp was above 105. This unit does not have a temperature dependent component. Installation would probably be very easy in a residential AC, but the RV AC was a fairly tight location and the connection to the return line (black) required me to cut into the existing wiring and recrimp a connection with the added wire. Review your wiring diagram (in your AC unit) before starting ! On my unit, I found that the new and old color wiring didn't match when everything was correctly connected; yours could be different. It's not difficult, but if you are uncomfortable working on electrical equipment, you should probably have this professionally installed.