Hi all,
First post. Hoping someone has some insight.
Background:
Our A/C has been blowing ambient air since we first tested it, after moving in last year (after the summer) - the fan ran outside, but I couldn't tell if the compressor was running. I eventually got around to pulling the outdoor electrical panel on the A/C to take a quick look, and there was a burned wire at the contactor (the common wire to the compressor). The heat had fused the contactor screw-down post, so it was clearly shot. I purchased a new, identical contactor, and identical Cap to be safe, and installed. I cut back the fried wire to the point where it had no visible insulation deformity, and no discoloration in the conductor, and reattached all wires EXACTLY as they were attached to the original contactor. My first thought as to why the wire got fried is a loose connection. When I fired the A/C back up, with everything hooked back up, same behavior - inside blowing ambient air. No condensing on the suction line at the outside line, so it doesn't seem like anything is happening. Both old and new caps tested within spec with my Fluke meter - 45uF/7.5uF dual +- 5%.
Went through a lot of troubleshooting, thinking. The (scroll) compressor ohmed out well, and seemed close (enough) to Coleland's specs. No short to ground from any Compressor contacts. I wanted to confirm the compressor was actually running (or drawing current), so I used a clamp meter and got 101A at momentary startup (LRA is 104 on this unit) which instantly receded to a steady 8.8A draw on the common line to the Compressor. RLA is 22A on this compressor, so a 9A draw seems reasonable based on my reading (30-40% of RLA).
I'm pretty close to calling in a professional because I obviously am not trained in dealing with refrigerant, and don't have the tools. But, I just now realized that the compressor had been replaced recently (manufacture date was 2018 - A/C unit is 15 years old), so I started thinking - "Did the person that replaced it also verify the Cap was properly speced?" Sure enough, Copeland's site says it should be a 55uF, not the 45uF found in the unit (and the replacement I bought was the exact same 45uF).
Question:
What symptoms, if any, would be noticeable with a Cap that was the wrong value, to the low side? Is a 10uF difference enough to completely throw the Cooling system into "no cooling whatsoever" mode? Could this be related to the burned line, or are they separate issues?
Thanks!
First post. Hoping someone has some insight.
Background:
Our A/C has been blowing ambient air since we first tested it, after moving in last year (after the summer) - the fan ran outside, but I couldn't tell if the compressor was running. I eventually got around to pulling the outdoor electrical panel on the A/C to take a quick look, and there was a burned wire at the contactor (the common wire to the compressor). The heat had fused the contactor screw-down post, so it was clearly shot. I purchased a new, identical contactor, and identical Cap to be safe, and installed. I cut back the fried wire to the point where it had no visible insulation deformity, and no discoloration in the conductor, and reattached all wires EXACTLY as they were attached to the original contactor. My first thought as to why the wire got fried is a loose connection. When I fired the A/C back up, with everything hooked back up, same behavior - inside blowing ambient air. No condensing on the suction line at the outside line, so it doesn't seem like anything is happening. Both old and new caps tested within spec with my Fluke meter - 45uF/7.5uF dual +- 5%.
Went through a lot of troubleshooting, thinking. The (scroll) compressor ohmed out well, and seemed close (enough) to Coleland's specs. No short to ground from any Compressor contacts. I wanted to confirm the compressor was actually running (or drawing current), so I used a clamp meter and got 101A at momentary startup (LRA is 104 on this unit) which instantly receded to a steady 8.8A draw on the common line to the Compressor. RLA is 22A on this compressor, so a 9A draw seems reasonable based on my reading (30-40% of RLA).
I'm pretty close to calling in a professional because I obviously am not trained in dealing with refrigerant, and don't have the tools. But, I just now realized that the compressor had been replaced recently (manufacture date was 2018 - A/C unit is 15 years old), so I started thinking - "Did the person that replaced it also verify the Cap was properly speced?" Sure enough, Copeland's site says it should be a 55uF, not the 45uF found in the unit (and the replacement I bought was the exact same 45uF).
Question:
What symptoms, if any, would be noticeable with a Cap that was the wrong value, to the low side? Is a 10uF difference enough to completely throw the Cooling system into "no cooling whatsoever" mode? Could this be related to the burned line, or are they separate issues?
Thanks!
source https://hvac-talk.com/vbb/threads/2227169-Wrong-capacitor-(too-low)-for-the-compressor-symptoms-I-would-expect?goto=newpost
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