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Heating & Air Conditioning

Hard Start Capacitor, what is its function and when to replace

8 years ago

last modified: 8 years ago

I have a couple of Carrier Infinity Units about 10+ years old. My contractor has regularly serviced them two times a year during that period. I am generally pleased with them, they certainly are professional. I'd like someone however to educate me on when a hard start capacitor needs to be replaced. The other day I was told by the tech. that one of the units required a new hard start capacitor. I gave the go ahead but there are some things I heard that I'd like someone here to 'vet'. (1) I was told that the unit would run without it but it would damage the compressor over the long run because the amp draw would be higher- this appears plausible to me, the unit was running OK. (2) He wanted to convince me that he was not cheating me by showing me the cap. He pointed to the terminal and said it was 'bowed out'. I'm extremely skeptical about this I think he should have mentioned Farads in evaluating the cap. (3) I paid $250 which after some research on prices appears to be at least $100 too high. I was paying for the service call through my annual agreement and I'm also supposed to be getting a discount since I have a service agreement, not sure how much.
Comments? Thanks

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Comments (2)

mike_home
8 years ago
In the spring I had maintenance done on my 6 year old Infinity system. I alternate the AC and furnace maintenance each year.

During the diagnostic testing the tech found one of the capacitors to be marginal. I think it was the start capacitor, but it could have been the run capacitor. I have a 10 year parts and labor warranty so the replacement was done for free. It was a little disappointing. The previous Carrier equipment was 25 years old when I replaced it. I never replaced any capacitors.

Many capacitors are made in Mexico and are not good quality. The original capacitor was rated for 370V, the tech put in one rated at 440V. In theory it should last longer, but if the dielectric material is low quality it will also fail.

If the capacitor showed signs of swelling, then it is time to replace it. Not sure if a bad start capacitor would cause damage to the compressor, but eventually the compressor will not start.

The price seems high if you are are supposed to be getting a discount. I would be curious to know what is the non-discounted price.
kalining45
8 years ago
about that time frame Carrier had made a complete run of " bad " compressors. They all came with hard start kits to fix the problem so

they didn't have to replace all the compressors. A swollen cap its usually

the fault of a bad electrical surge or brown out. To answer the other

question I buy hard start kits for $19.00. My customer cost would be

$28.00. Maybe $35.00 tops depends on how much power the kit has

to have.
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Looking at the rust on the cap,I believe the connection coroded causing a high resistane ( very common occurance on electrical exposed to the elements). The resistance literly tuned the metal and wire red. As already stated,caps are very cheap so just go ahead and replace it. Here's pointers to help you out. Draw a diagram of the wire connectios paying close attention to markings on cap that say (compressor) and ( fan). That is a dual cap. Take it with you. You can ask but there is little chance they have one. Buy 2 caps,one for each value. Don't freak if they want to sell you a 10% higher mfd or 440 volt where yours is 330,it will work fine. While you are there buy some high heat wire terminals ( see the 2 slots in the old terminals?) You will need to build a simple jumper with 2 caps,be sure to us large enough wire. The terminals must be perfectly CLAMPED TIGHT on wires or the same problem will return eventualy. Good luck.
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