togor
05-28-2018, 04:58
So a little bit of a heat wave, and so we go to turn on the central AC a couple of days ago. No joy. What changed? Well we had a new furnace installed last winter. Snag #1 back then is that we paid for a 95% efficient unit only to have them put in a 91% unit. A fact I discovered about a week later. The company cut me a check pretty quick for an amount north of my bottom line there so OK, settled. Snag #2 now is that our AC doesn't kick in.
Well I'm tired from spending all of yesterday in the driveway working on cars, but I get the look from my wife that says I really need to be getting on this AC thing before it gets dark. AC contactor outside in the unit looks good, no corrosion, Ohms good. Start dinking around with the thermostat wiring in the basement. Have to look up the colors on the web because it's been 15 years and I'm tired, LOL. In the end I figured out that the furnace installer had wired up the AC contactor wrong when he put in the new unit. He should have brought all 5 wires out of the furnace but he only brought 4. On this furnace the AC contactor needs to be wired between yellow and blue to kick in. He had it wired in series between the thermostat and furnace yellow wires.
Being a circuits guy I could work this out from first principles and now it works. And when the service guy calls back today, my wife can cheerfully tell him that their installer screwed up the job and her husband fixed it. Thermostat wiring ain't exactly rocket science and I'm no genius for fixing it, but on the other hand the guy who did the install, who does this for a living and who has a much bigger house than me (or so he tells me), didn't get it right himself.
Well I'm tired from spending all of yesterday in the driveway working on cars, but I get the look from my wife that says I really need to be getting on this AC thing before it gets dark. AC contactor outside in the unit looks good, no corrosion, Ohms good. Start dinking around with the thermostat wiring in the basement. Have to look up the colors on the web because it's been 15 years and I'm tired, LOL. In the end I figured out that the furnace installer had wired up the AC contactor wrong when he put in the new unit. He should have brought all 5 wires out of the furnace but he only brought 4. On this furnace the AC contactor needs to be wired between yellow and blue to kick in. He had it wired in series between the thermostat and furnace yellow wires.
Being a circuits guy I could work this out from first principles and now it works. And when the service guy calls back today, my wife can cheerfully tell him that their installer screwed up the job and her husband fixed it. Thermostat wiring ain't exactly rocket science and I'm no genius for fixing it, but on the other hand the guy who did the install, who does this for a living and who has a much bigger house than me (or so he tells me), didn't get it right himself.