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heatncoolrepair
heatncoolrepair, HVAC Technician
Category: HVAC
Satisfied Customers: 75
Experience:  13 Years of Residential Furnace & A/C Repair Experience.
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My old thermostat has 5 wires G, RC, Y, W, 4 my new

Customer Question

My old thermostat has 5 wires G, RC, Y, W, 4 my new thermostat has 4 wires G, R, Y, W what do I do?
JA: Just to clarify, do you think this is a larger HVAC problem, or something specific to the thermostat?
Customer: Specific
JA: Do you plan on doing the work yourself?
Customer: Yes
JA: Anything else we should know to help you best?
Customer: No
Submitted: 2 months ago.
Category: HVAC
Expert:  heatncoolrepair replied 2 months ago.

Hello, welcome to Just Answer! I will be assisting you. Please give me a moment to review the information you have provided. Thank you.

Expert:  heatncoolrepair replied 2 months ago.

What is the 5th wire on the old thermostat?

Customer: replied 2 months ago.
G, RC, Y, W, 4
Customer: replied 2 months ago.
4 is red
Expert:  heatncoolrepair replied 2 months ago.

That does not sound right. Do you have the brand & model number of the old thermostat?

Expert:  heatncoolrepair replied 2 months ago.

Sure it is not a "C"?

Customer: replied 2 months ago.
Sears C387-47028
Expert:  heatncoolrepair replied 2 months ago.

Ok, thanks....standby while I look it up.

Customer: replied 2 months ago.
G= green wire
RC= Blue wire
Y= Yellow wire
W= White wire
4= Red wire
Expert:  heatncoolrepair replied 2 months ago.

Ok, the red wire labeled 4 is actually RH. You have a 2 transformer system, so on the new thermostat, remove the jumper between RC and RH. Then connect the red wire on terminal 4 from the old thermostat to RH on the new thermostat. Make sure you remove the jumper though between RC and RH.

Expert:  heatncoolrepair replied 2 months ago.

Does your new thermostat have RC and RH with a jumper between them, or just R? I was just assuming it does.

Customer: replied 2 months ago.
Just an R the only jumper I have is HE/HG with is for electric/gas
Expert:  heatncoolrepair replied 2 months ago.

Ok, you will need a different thermostat then that has RC, RH, G, Y, and W. Any more questions? My goal is to provide you with excellent service - if you feel you have received anything less, please reply back as I am happy to address follow - up questions. Kindly rate me when you are done.

Customer: replied 2 months ago.
Here is a picture of the new one UPM THM301M
Customer: replied 2 months ago.
There was a post on here to just clip the Blue RC
Expert:  heatncoolrepair replied 2 months ago.

Yea, the new thermostat will not work for your application. The H terminals are for a humidifier. RH is for the furnace and RC is for the air conditioner. If you do that then your A/C won't kick on.

Expert:  heatncoolrepair replied 2 months ago.

Any other questions?

Customer: replied 2 months ago.
Ok thanks
Expert:  heatncoolrepair replied 2 months ago.

No problem. Have a good day!

Expert:  heatncoolrepair replied 2 months ago.

http://www.upm-marketing.com/tutorial/301/index.html This is the link to the tutorial to replace your thermostat, which states if your original thermostat has 5 or more wires you will need a different model of their thermostat.

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