The decision: which compressor start part should you buy?
An air conditioner that labors to start or a refrigerator compressor that clicks without running often comes down to a small electrical assist. In the HVAC refrigeration compressor parts world, you generally choose between hard start kits for 3.5-5 ton AC condensers and start relays for refrigerator compressors. This guide compares four parts across that range: two hard start devices for AC condensers and two Embraco start devices for fridges. The listed prices run from $19.99 to $34.67, but the right pick depends on the equipment you are fixing, not the price alone.
Quick take
If you're working on a 3.5-4-5 ton AC condenser, the 5-2-1 Compressor Saver CSRU2 and the Rectorseal Kickstart KS1 both aim to deliver strong starting support. For refrigerator compressor repair, the two Embraco TSD2 parts are relays: the QD TSD2 Start Device with 1/4" connectors, and the QD2 TSD2 Start Relay Device. Listed prices in this group run from $19.99 to $34.67, with the Rectorseal at the top and the Embraco QD2 relay at the bottom.
Listed-price comparison
| Product | Listed price | Price bar |
|---|---|---|
| Rectorseal Kickstart Compressor HVAC Hard Start Device KS1 | USD 34.67 | |
| 5-2-1 COMPRESSOR SAVER CSRU2 Hard Start Kit 3.5-4-5 tons AC HVAC CONDENSER UNITS | USD 28.99 | |
| Embraco QD TSD2 Refrigerator Compressor Start Device 513605007 1/4" Connectors | USD 22.49 | |
| NEW Embraco QD2 TSD2 Refrigerator Compressor Start Relay Device | USD 19.99 |
Decision matrix
| Product | Use case | Watch out |
|---|---|---|
| Rectorseal Kickstart KS1 | Condenser hard start with 2-wire relay and start capacitor | Most expensive option in this set |
| 5-2-1 Compressor Saver CSRU2 | AC condenser hard start kit with 5-2-1 wiring | Priced above the two refrigerator relay parts |
| Embraco QD TSD2 Start Device | Refrigerator compressor start relay | Not for AC condensers |
| Embraco QD2 TSD2 Start Relay Device | Refrigerator compressor relay for Kenmore Elite, Frigidaire, Kenmore Pro | Refrigerator-only relay |
Product notes
Rectorseal Kickstart Compressor HVAC Hard Start Device KS1
This hard start device is built for 3.5-5.0 ton HVAC compressor units and pairs a 2-wire potential relay with a start capacitor. It carries the Rectorseal Kickstart name, uses item number 96505, and is marked OEM-tested and approved. It is the most expensive option in this set, so it fits shoppers who want a single 2-wire hard start device for larger residential AC condensers. The trade-off is the price compared with the other hard start kit in the group. It is not a refrigerator compressor relay part, so the equipment type will determine whether this is the right direction.
5-2-1 COMPRESSOR SAVER CSRU2 Hard Start Kit 3.5-4-5 tons AC HVAC CONDENSER UNITS
This kit is targeted at 3.5, 4, and 5 ton AC condenser units and uses the 5-2-1 wiring order: black to common, striped to start, red to run. It includes a ZRUB hard start capacitor, a cable tie, and two mounting screws, and it is compatible with CSR-U2 hard start capacitor kits. The CSRU2 model is UL certified. For a homeowner or technician who wants a complete AC condenser hard start package with color-coded wiring, this is the straightforward choice among the two hard start products. It is not a refrigerator compressor relay, so keep it on the HVAC side.
Embraco QD TSD2 Refrigerator Compressor Start Device 513605007 1/4" Connectors
This Embraco part is a gray refrigerator compressor start device with 1/4-inch connectors. The model is the QD TSD2, and the set includes a start relay. In this price set, it sits between the lower-priced Embraco relay and the two AC hard start kits. If you are repairing a refrigerator compressor and want a stated connector size, this part carries that detail. It is not intended for 3.5-5 ton AC condenser work; its category is refrigerator compressor start devices. Because the two Embraco models look similar on paper, keep this one separate as the relay with the 1/4-inch connector size at a mid-range listed price.
NEW Embraco QD2 TSD2 Refrigerator Compressor Start Relay Device
This is the lowest listed price in the set, and it is a gray refrigerator compressor start relay device under the model QD2 TSD2. The compatibility list names Kenmore Elite, Frigidaire, and Kenmore Pro refrigerators, which makes it useful when you already know your appliance brand. Like the other Embraco part, this is not an AC condenser hard start kit; it is positioned for refrigerator compressor repair. The model name QD2 TSD2 is close to the QD TSD2 above, but this one carries the relay device wording and the lower listed price. If you are choosing between the two Embraco parts, price and brand compatibility are the main details to compare.
Final recommendation by use case
For an AC condenser hard start project, the 5-2-1 Compressor Saver CSRU2 at $28.99 gives you a complete capacitor and wiring kit; the Rectorseal Kickstart KS1 at $34.67 is a higher-priced 2-wire alternative for the same type of unit. For refrigerator compressor work, choose the Embraco QD TSD2 Start Device at $22.49 if you want a stated connector size and a start relay. Choose the Embraco QD2 TSD2 Start Relay Device at $19.99 if your refrigerator is in the listed compatibility range and you want the lowest listed price. Match the part to your compressor type first, then use listed price and connector details to make the final call.
