Had a no cool on a little Carrier 4 ton RTU yesterday. Small jewelry store, 45 degrees outdoors, high internal gains. Bad econo. Has a factory installed Carrier "EconoMi$er+," Circuit card with two buttons and 4 LEDs, outdoor air thermistor and discharge air thermistor running 2-10 vcd mod motor. The LEDs indicated a "Fault." Got it reset (after about 100 punches of the buttons), still no operation and then got another fault. Couldn't clear it this time. But I then proved the mod motor worked. Bad card or bad sensors? Figured I just replace them all.
So, I make a 35 minute drive to the local distributor, with unit mod and ser number, economizer mod number and build date and the circuit card P/N. Counterguy looks it up in his computer, "Sorry, it's obsolete."
"Obsolete? It's a freakin' 2004 unit. It's three years old! Look at the date codes. I need a new circuit card and thermistors." I reply.
"Nope. You need a whole new economizer." He tells me.
"No way. That'll be over twice the price and I'd have to call the shop for a second man just to get it on the roof. It's a two level mall. And I know you don't stock it here, I'd have to drive to the other side of town to the main warehouse to pick it up. That's another 2 hours, round trip. The customer is gonna go nuts at that cost. It's three years old! There has to be a replacement!"
So the counterguy calls the factory. He's on hold for 45 minutes. He finally gets a P/N for a "kit" to replace the board. Better, he even has it in stock.
"First one of them I've ever sold." He comments.
It's a Honeywell W7212 econo control prewired with the Carrier econo plug, h/w enathalpy sensor, new discharge sensor, a tin cover. Expensive, but the "kit" stuff always is - and counting the labor to field wire the new components, it's cheaper to the customer. So I take it and run.
An hour and a half later it's all mounted and wired in - I was flyin, losing daylight. I go to the instructions looking for info beyond schematic and the "min position" and "A-B-C-D" enthalpy settings to find out how to set it up. Wow, probably the first time I've read instructions, beyond the schematic, this decade! Not a word in the instructions about set-up. Guess Carrier forgot that.
But the only reason I've explained the whole job here is cuz I wanted you guys to know what the last line in the instructions was. It said:
"14: Save the old Supply Air Temp sensor and tape it to the W7212 controller cover. We will install this (if desired) in Vegas."
Does anybody have the slightest idea WTF that means? Vegas???
(I scanned the instructions into a .gif. They probably would be too small to be readable here as an attachment, but I'll email them to you if you think I'm making this up. And I'm not making it up!)