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Debugging my central air conditioning unit
Jul. 1st, 2006 10:10 pmYesterday, I did something I'm really proud off. I fixed our central air conditioning all by myself and it costed me only about one hour of labor and 30 cents in parts. It was broken since sometime between the 18th and the 23rd (when we were out of town).
At first, I wanted to call an AC repair outfit, then I thought of calling dad (all-around handyman who just finished his own 3000 sq.ft house, as a quasi-GC, subcontractor and hammer-yielding grunt). But then I thought of doing a few simple common-sense checks before I call him. I turned it on: warm air was moving through the system you see. So, I thought maybe the freon line leaked, so I inspected it from the furnace all the way to the heat pump. No obvious leaks.
While outside looking at the pipes, I noticed something odd: the heat pump fan was turning on and off at regular 20+ seconds intervals. That did not make sense given that a normal unit would have worked continuously until the house would have cooled down. So, I thought that we're lucky we don't have a leak. Marina thought that we might have a bad relay, I thought that maybe the fan was malfunctioning, so I stopped the AC unit, and I flipped the safety switch for the heat pump to off (which effectively cut off electricity to it).
I opened the top of the heat pump and removed the fan. It looked OK, the wiring looked OK, but there was no relay in that housing, so I put it back. After going back inside and doing some googling for troubleshooting heat pumps (coming up empty), I remembered that the heat pump had some extra screws on one vertical edge suggesting that that's where the relays were housed.
So, I went back outside, opened the side housing and noticed almost right away something obviously wrong: a disconnected burnt-out wire. So, I took it out, went to the hardware store and found a replacement clamp for 30c. I cleaned the wire, attached the new clamp at the burnt end and put it back in the housing. I restarted the central air unit and within a minute cold air started blowing through the vents again. Yeay!
Now, the relays, the capacitor, the wires are almost 20 years old and I can't figure out why the wire burnt out in the first place, but as long as it works now, I'm happy. I do suspect that some insects might have caused the problem (there were two spiders and some dead bugs in the relay housing), although water leakage might be a more credible culprit (the cover seemed to have water marks on the inside). Another suspect thing was that the housing had two capacitor: one small one attached firmly to the housing and not connected to anything and a much larger one attached to the relay and almost hanging in mid-air, held in place by some electric tape to some wires.
Whatever the cause of the burnt wire, I'm glad I did the simple common sense checks and probably saved at least $50. I can't wait to tell dad :-)
At first, I wanted to call an AC repair outfit, then I thought of calling dad (all-around handyman who just finished his own 3000 sq.ft house, as a quasi-GC, subcontractor and hammer-yielding grunt). But then I thought of doing a few simple common-sense checks before I call him. I turned it on: warm air was moving through the system you see. So, I thought maybe the freon line leaked, so I inspected it from the furnace all the way to the heat pump. No obvious leaks.
While outside looking at the pipes, I noticed something odd: the heat pump fan was turning on and off at regular 20+ seconds intervals. That did not make sense given that a normal unit would have worked continuously until the house would have cooled down. So, I thought that we're lucky we don't have a leak. Marina thought that we might have a bad relay, I thought that maybe the fan was malfunctioning, so I stopped the AC unit, and I flipped the safety switch for the heat pump to off (which effectively cut off electricity to it).
I opened the top of the heat pump and removed the fan. It looked OK, the wiring looked OK, but there was no relay in that housing, so I put it back. After going back inside and doing some googling for troubleshooting heat pumps (coming up empty), I remembered that the heat pump had some extra screws on one vertical edge suggesting that that's where the relays were housed.
So, I went back outside, opened the side housing and noticed almost right away something obviously wrong: a disconnected burnt-out wire. So, I took it out, went to the hardware store and found a replacement clamp for 30c. I cleaned the wire, attached the new clamp at the burnt end and put it back in the housing. I restarted the central air unit and within a minute cold air started blowing through the vents again. Yeay!
Now, the relays, the capacitor, the wires are almost 20 years old and I can't figure out why the wire burnt out in the first place, but as long as it works now, I'm happy. I do suspect that some insects might have caused the problem (there were two spiders and some dead bugs in the relay housing), although water leakage might be a more credible culprit (the cover seemed to have water marks on the inside). Another suspect thing was that the housing had two capacitor: one small one attached firmly to the housing and not connected to anything and a much larger one attached to the relay and almost hanging in mid-air, held in place by some electric tape to some wires.
Whatever the cause of the burnt wire, I'm glad I did the simple common sense checks and probably saved at least $50. I can't wait to tell dad :-)
