Home AC Not Working, Start Capacitor Discussion

[MoVolvos]

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The AC unit is 2006. Had to replaced the furnace / evaporator fan capacitor twice the last two years. Both times the fan speed was low and the evaporator coil iced up so almost no air flow from the ducts. Initially thought it was low refrigerant causing the coil icing. This year the unit is not running again but the furnace fan speed was blowing normally. Checked the condensing unit outside and the fan would hum while the compressor would click and tried to start.
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1) Had good voltage at contactor and was working properly. Removed and sanded contacts with 600 grit to be sure.
2) Fan would spin if you helped it along with a stick or screw driver .
3) Capacitor was bulging but didn't know if was a dual run unit so thought the compressor was bad.
4) The scroll compressor didn't looked like it had a capacitor built in. After watching a Youtube video realized it could be a dual run so it should be for both the compressor and condensing fan.
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For good measure ordered a new contactor, new capacitor and a new to me hard start capacitor. To think I used to do load calcs, design walk ins, blast freezers including sourcing and putting it all together, Oxy Acetylene welding with nitrogen and all. Have a Universal CFC so turn key except for the electrical .

Parts will arrive tomorrow so hopefully that it?

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[volvolugnut]

My Heat pump unit is about 15 years old. Last summer I noticed it was slow to start. It would buzz then fail to start about 10 times before actually starting compressor. My guess of a bad compressor start condenser was correct and after the service tech replaced all was good again.
volvolugnut

[MoVolvos]

My Heat pump unit is about 15 years old. Last summer I noticed it was slow to start. It would buzz then fail to start about 10 times before actually starting compressor. My guess of a bad compressor start condenser was correct and after the service tech replaced all was good again.
volvolugnut

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My first time encounter with a bad compressor start capacitor. Have change quite a few evaporator and condensing fan start capacitors however. At that age I wonder how many companies will tell the consumer it need a compressor so will either replace the compressor, compressor package unit or the entire system including the furnace .

One reviewer indicated a company wanted $900 to install two Hard Start Capacitors, one for each unit, to assist the new capacitor due to the age of the older compressor (see video). $15 to $50 dollar part depending on the type. 10 minute job max from beginning to end. The panel is already off so just a few minutes to install. Worst than a Stealership!
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Hard Start Capacitor.png (109.75 KiB) Viewed 1831 times

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[abscate]

Checked the condensing unit outside and the fan would hum while the compressor would click and tried to start.

Solid diagnosis!



HVAC at home servicing can be a real circus of fools. Our main board on our Carrier went years ago due to mouse intrusion, Mickey got zapped on the line voltage and died on the board, then bled out and shorted it

$150 house call. Quoted $540 for board plus revisit of $250 to put in 5 days later , less $150 credit for diagnosis.

SWMBO drove ten minutes to Frank Webb, picked up board for $125 and plugged in, she is a instrument chemist by training

It probably pays to replace fan and compressor start caps on a ten year, PM basis.

[MoVolvos]

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Installed Capacitor & Contactor last weekend, Not much room so decided against the Hard Start Capacitor. Unit is smaller but is has the same ratings.
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IMG_0277.jpeg (524.47 KiB) Viewed 1728 times

IMG_0278.jpeg (447.6 KiB) Viewed 1728 times

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[abscate]

I Can’t remember if this type of cap has polarity but in any event it’s good practice to photo and replace wires in the same place if the geometry is the same. I don’t believe they do have polarity

You do have to match the right cap to the load, 5uF is typically blower. 50uF for compressor

[MoVolvos]

I Can’t remember if this type of cap has polarity but in any event it’s good practice to photo and replace wires in the same place if the geometry is the same. I don’t believe they do have polarity

You do have to match the right cap to the load, 5uF is typically blower. 50uF for compressor

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Fan, Herm & Ground I believe were on the cap for the 3 connectors. Herm for Hermetic Sealed Compressor.
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[abscate]

Just replaced a cap on my nice garage compressor too. Same symptoms, stall on start, blow breaker.

$10